Chemistry Q&A

Chem Q&A

2010-06-22T17:55:00.000-07:00

This is the index for Chemistry Q&A videos developed by Dr. Glenn V. Lo, faculty colleagues (Ms. April Dupre, Dr. Vincent Giannamore, Ms. Cynthia Lamberty, and Dr. Jeremy Wessel) and students at Nicholls State University (Department of Physical Sciences). The development of most of these videos is funded through Project VALUE (Video Assessment Library for Undergraduate Education) by the Louisiana Board of Regents SELECT Grants Program (Contract No. LA-DL-SELECT-13-07/08). Other videos were developed by students for honors credit in Chemistry courses at Nicholls.

LEARNING OBJECTIVES

PART I. INTRODUCTORY CONCEPTS
1-1 Differentiate hypothesis, observation, theory, and law, 1-2Differentiate physical states of matter in terms of shape, volume (compressibility), intermolecular distances, molecular motion, 1-3Describe separation techniques for samples of matter, 1-4Differentiate elements, compounds, and mixtures, 1-5 Write correct symbols for elements, 1-6 Classify elements based on their location in the periodic table, 1-7 Describe naturally-occurring forms of elements, 1-8 Describe the law of conservation of matter (mass), 1-9Describe and apply the law of definite composition, 1-10 Describe basic atomic structure (subatomic particles), 1-11 Interpret symbols for isotopes, 1-12 Describe how isotopes can be separated, 1-13Describe how the currently accepted model of the atom evolved from Dalton through Rutherford, 1-14 Describe how ions are formed from atoms, 1-15 Classify ions as cations or anions, 1-16 Interpret symbols and formulas of ions, 1-17 Predict stable monatomic ions formed from atoms, 1-18 Differentiate and predict ionic and covalent bonding, 1-19 Describe and differentiate molecules and polyatomic ions, 1-20 Interpret formulas of molecules and polyatomic ions, 1-21Classify polyatomic ions as oxoanions or non-oxoanions, 1-22Read/write formulas of polyatomic ions, 1-23 Classify compounds as molecular or ionic, 1-24 Write formulas of molecular and ionic compounds based on a description of the atoms or ions that make up a formula unit, 1-25 Differentiate ionic and molecular compounds in terms of physical properties, 1-26 Read and write formulas of binary compounds, 1-27 Read and write formulas of compounds containing polyatomic ions, 1-28 Read and write formulas of acids, 1-29 Describe and differentiate physical and chemical changes/properties, 1-30Identify reactants and products of a chemical reaction, 1-31 Construct a balanced chemical equation, 1-32 Classify and predict products of simple reactions

PART 1A. MEASUREMENTS
1A-1 Interpret SI prefixes, 1A-2 Identify significant figures in properly reported measurements, 1A-3 Relate uncertainty (precision) to how measurements are reported, 1A-4 Properly round off results of calculation involving measurements, 1A-5 Convert units, 1A-6Convert temperature readings, 1A-7 Convert temperature differences or changes, 1A-8 Solve problems dealing with measurements of physical properties (mass, volume, density, temperature, heat, heat capacity, solubility)

PART 2. ATOMIC STRUCTURE.
2-1 Describe electromagnetic radiation in terms of waves and photons, 2-2 Describe the Bohr model and relate to atomic spectra, 2-3 Describe orbitals and rules for assigning electrons to orbitals, 2-4Write or identify ground state and excited state electron configurations, 2-5 Relate (ground-state) electron configuration of an atom to its location in the periodic table, 2-6 Relate properties (size, ionization energy) of an atom to its location in the periodic table, 2-7Relate electron configuration and properties of ions to the parent atoms' location in the periodic table

PART 3. MOLECULAR STRUCTURE
3-1 Relate electronegativity to location of atom in the periodic table,3-2 Relate electronegativity and bond polarity, 3-3 Write and interpret Lewis dot symbols, 3-4 Interpret Lewis structures, 3-5 Draw Lewis structures, 3-6 Recognize and differentiate resonance and isomeric structures, 3-7 Determine formal charges, 3-8 Use formal charges and electronegativity to assess feasibility of a structure or extent of contribution to a resonance hybrid, 3-9 Recognize exceptions to the octet/duet rule, 3-10 Relate bond length to bond order and atomic sizes, 3-11 Describe molecular geometry using VSEPR, 3-12 Predict molecular polarity, 3-13 Describe intermolecular forces and relate to molecular structure and properties, 3-14 Use valence bond theory to explain molecular geometry, 3-15 Apply molecular orbital theory to diatomic molecules

PART 4. MOLE CONCEPT, STOICHIOMETRY
4-1 Distinguish between masses of individual atoms and average masses, 4-2 Define mole and Avogadro number, 4-3 Relate mole count to individual count, 4-4 Count atoms and molecules in molecular compounds or ions in an ionic compound, 4-5 Relate moles and mass of pure substances, 4-6 Determine amount of element present in a compound, 4-7 Determine empirical and molecular formulas, 4-8Relate amounts of reactants and products in a chemical reaction, 4-9Determine limiting reactant and theoretical yield, 4-10 Determine amount of unreacted excess reactant

PART 5. SOLUTIONS AND AQUEOUS REACTIONS
5-1 Differentiate solutions from compounds, 5-2 Differentiate solution, colloids, suspensions, and coarse mixtures, 5-3 Describe the dissolution of ionic and molecular compounds in water, 5-4 Classify solutions as saturated, supersaturated or unsaturated, 5-5 Classify ionic compounds as soluble or insoluble in water, 5-6 Recognize chemical equations for precipitation reactions, 5-7 Predict if a precipitation reaction could occur, 5-8 Write net ionic equations for precipitation reactions, 5-9 Describe strong and weak acids, 5-10Write chemical equations to represent ionization of acids in water, 5-11 Describe strong and weak bases, 5-12 Write chemical equations to represent acid-base reactions, 5-13 Write net ionic equations to represent acid-base reactions, 5-14 Calculate amount of solute given volume and molarity of solutions, 5-15 Calculate molarity of solutions and of ions in solution, 5-16 Solve dilution problems, 5-17 Solve stoichiometry problems involving solutions

PART 6. SOLIDS, LIQUIDS, AND GASES
6-1 Relate gas pressure to heights of liquid columns, 6-2 Relate Pressure, Volume, Temperature, and moles of gas, 6-3 Determine molar mass of a gas from density, Pressure, and Temperature data,6-4 Identify and apply empirical gas laws, 6-5 Apply Dalton's Law of partial pressures, 6-6 Solve stoichiometry problems involving gases,6-7 Interpret pressure and temperature in terms of molecular motion,6-8 Use Graham's law of effusion to compare effusion rates and determine molar mass of gas, 6-9 Describe and interpret real gas behavior, 6-10 Interpret one-component phase diagrams, 6-11Describe solid structure

PART 7. REDOX REACTIONS
7-1 Classify half reactions as reduction or oxidation, 7-2 Assign oxidation numbers, 7-3 Differentiate oxidation number from charge,7-4 Identify atoms oxidized or reduced based on oxidation numbers,7-5 Balance a redox reaction using oxidation number method, 7-6Balance redox half reactions in aqueous solution, 7-7 Construct a balanced redox reaction given two balanced half reactions

7-7 Construct a balanced redox reaction given two balanced half reactions

2009-06-05T09:31:00.001-07:00

7-6 Balance redox half reactions in aqueous solution

2009-06-05T09:28:00.001-07:00

7-6-1. Consider the half-reaction (unbalanced) in acidic solution:
HClO₂(aq) ==> Cl₂(g)
When this half reaction is balanced using the smallest set of whole number coefficients, what is the coefficient of H⁺(aq) and how many electrons are involved?

7-6-2. Consider the half-reaction (unbalanced) in basic solution:
ClO₂^-(aq) ==> Cl₂(g)
When this half reaction is balanced using the smallest set of whole number coefficients, what is the coefficient of OH^-(aq) and how many electrons are involved

7-6-3. When the following half reaction
H₂SO₃(aq) ==> SO₄ ^2-
is balanced in acidic solution using the smallest of whole Publish Postnumbers, what is the coefficient of H2O and how many electrons are involved?
A. 1, 2 B. 1, 3 C. 2, 3 D. 3, 1

7-6-4. Which of the following is a reduction half reaction?

A.SO_{2 (g)} ==> SO₃^2-_(aq)
B.SO₄^2-_(aq) ==> SO₃^2-_(aq)
C.S^2-_(aq) ==> SO₃^2-_(aq)

7-5 Balance a redox reaction using oxidation number method

2009-06-05T09:27:00.001-07:00

7-5-1. When the following chemical equation is balanced, what is the ratio of the coefficients of NO and Cu(NO₃)₂?
Cu(s) + HNO₃(aq) ==> NO(g) + Cu(NO₃)₂(aq) + H₂O(l)
A. 1:1, B. 1:2, C. 2:1, D. 2:3, E. 3:2

7-5-2. When the following chemical equation is balanced, what is the ratio of the coefficients of MnCl₂ and Cl₂?
KMnO₄ (s) + HCl (aq) ==> MnCl₂(aq) + Cl₂(g) + KCl(aq) + H₂O(l)
A. 1:2, B. 2:3, C. 2:4, D. 1:5, E. 2:5

7-3 Differentiate oxidation number from charge

2009-06-05T09:25:00.000-07:00

7-3-1. Which of the following is false?
A. The charge of mercury in mercury one is +1
B. The oxidation number of mercury in mercury one is +1
C. The charge of mercury in mercury two is +2
D. The oxidation number of mercury in mercury two is +2

7-3-2. Which of the following is false?
A. The charge of oxygen in carbon monoxide is -2
B. The oxidation number of oxygen in carbon monoxide is 2
C. The charge of oxygen in Magnesium Oxide is 2
D. The oxidation number of oxygen in magnesium oxide is -2

7-1 Classify half reactions as reduction or oxidation

2009-06-05T09:24:00.001-07:00

7-1-1. In a reaction where magnesium metal reacts to form a compound, magnesium is said to be
A. oxidized, B. reduced, C. the oxidizing agent

7-1-2. When Cl₂ (g) reacts with a metallic element to form an ionic compound, we say that chlorine is
A. oxidized, B. reduced, C. the reducing agent

7-1-3. When Br₂(l) is produced from the reaction involving a bromine-containing binary ionic compound, the half reaction leading to the formation of Br2 is classified as
A. oxidation, B. reduction,
C. oxidation or reduction depending on what the compound is

6-11 Describe solid structure

2009-06-05T08:38:00.001-07:00

6-10 Interpret one-component phase diagrams

2009-06-05T08:37:00.001-07:00

5-16 Solve dilution problems

2009-06-04T10:44:00.001-07:00

5-16-1. Consider a 0.500 NaOH(aq). If enough water is added to a 10.0 mL sample of this solution in order to bring up the total volume to 100.0mL, what is the molarity of the resulting solution?
A. 0.0500M
B. 1.00 M
C. 2.00M
D. 5.00M

5-16-2. How much water should be added to a 100.0mL sample of 6.000M NaOH in order to dilute the solution to 3.000M?
A. 100.0 mL
B. 200.0 mL
C. enough to bring the total volume to 200.0 mL
D. none of the above

3-10 Relate bond length to bond order and atomic sizes

2009-06-02T09:06:00.001-07:00

6-9 Describe and interpret real gas behavior

2008-12-31T16:22:00.001-08:00

6-9-1. A gas occupies a volume of 22.0 L/mol at STP. Which of the
following explains the deviation from ideal behavior?
A. predominance of attractive forces among the molecules
B. predominance of repulsive forces among the molecules
C. absence of attractive forces among the molecules
D. absence of repulsive forces among the molecules

6-9-2. A 2.00 mol sample of gas occupies a volume of 11.0 L at 298K and 5.00 atm. These values suggest that…
A. the gas is behaving ideally
B. the gas is not behaving ideally and the deviation is due to
predominance of attractive forces
C. the gas is not behaving ideally and the deviation is due to
the predominance of repulsive forces

6-9-3. The compression factor for a 2.50 L gas sample is 1.20. If the gas were ideal, at the same temperature and pressure, the volume would be
A. higher than 2.50 L,
B. smaller than 2.50 L,
C. the same,
D. different, but information is insufficient

6-9-4. The compression factor for a gas sample is 0.90; its pressure is 20.0 atm. If the gas were ideal, at the same temperature and volume, the pressure would be
A. higher than 20.0 atm, B. lower than 20.0 atm, C. the same,
D. different, but information is insufficient

6-8 Use Graham's law of effusion to compare effusion rates and determine molar mass of gas

2008-12-31T16:21:00.001-08:00

6-7 Interpret pressure and temperature in terms of molecular motion

2008-12-31T16:19:00.001-08:00

6-6 Solve stoichiometry problems involving gases

2008-12-31T16:17:00.001-08:00

6-6-1. A piece of Mg ribbon is reacted with hydrochloric acid. If 224 mL of hydrogen gas is produced at 25.0oC, 1.00 atm, how much HCl was consumed? The reaction is:
Mg(s) + 2 HCl(aq) == MgCl₂(aq) + H₂(g)

6-6-2. Consider the combustion of urea:
2 CO(NH₂)₂ (s) + 3 O₂(g) == 2 CO₂(g) + 2 N₂(g) + 4 H₂O(l)
Suppose 3.00 g of urea were burned in excess oxygen in a fixed-volume 1.00-L sealed container that initially contained 2.00 atm of O2 at 298K. Estimate the final pressure in the container at
298K?

6-6-3. Consider the hypothetical reaction:
2 A(g) == B(g) + 3 C(g)
Suppose a fixed-volume container initially contains 2.00 mol of pure A(g) at a pressure of 0.500 atm. Hours later, the pressure, at the same temperature, is found to be 0.800 atm. How many moles of B(g) are present in the final mixture?

6-5 Apply Dalton's Law of partial pressures

2008-12-31T16:16:00.001-08:00

6-5-1. Hydrogen gas is collected over water at 25^oC. The vapor pressure of water at this temperature is 23.8 Torr. If the total pressure of the gas is 755.0 Torr, what is the partial pressure of hydrogen?
A. 731.2 Torr, B. 778.8 Torr, C. 23.8 Torr, D. None of the above

6-5-2. A 5.0 mg sample of gas "X" is found to have a pressure of 0.100 atm at 298K in a given container. A 10.0 mg sample of gas "Y," placed in the same container is found to have a pressure of 0.150 atm at 298K. What would be the total pressure of a mixture of 5.0 mg "X" and 10.0 mg "Y" in the same container at 298K? (assume no reaction)
A. 0.050 atm, B. 0.105 atm, C. 0.250 atm, D. 2.0 atm

6-5-3. A mixture containing 0.200 mol H₂ and 0.300 mol N₂ has a total pressure of 720.0 Torr. What is the partial pressure of H₂ in the mixture?
A. 144 Torr, B. 216 Torr, C. 288 Torr, D. 360 Torr

6-4 Identify and apply empirical gas laws

2008-12-31T16:14:00.001-08:00

6-4-3. What is the final volume of a gas, originally at (25.0 L, 25.00^oC) if it is heated to 50.00^oC at constant pressure?
A. 12.5 L, B. 27.1 L, C. 50.0 L

6-4-4. What is the final pressure of a gas, originally at (30.0 L, 250.0 Torr) if it is compressed to 15.0 L at constant temperature?
A. 125 Torr, B. 235 Torr, C. 280 Torr, D. 500 Torr

6-4-5. What is the final volume of a gas, originally at (30.0 L, 250.0 Torr, 25^oC) if its pressure and temperature are changed to (500.0 Torr, 115^oC)?
A. 19.5 L, B. 46.0 L, C. 69.0 L, D. 78.1 L

3-15 Apply molecular orbital theory to diatomic molecules

2008-12-31T16:12:00.001-08:00

6-1 Relate gas pressure to heights of liquid columns

2008-12-31T16:10:00.000-08:00

6-1-1. What is the pressure due to a vertical column of mercury that is 760.0 mm long?
760.0 Torr, B. 760.0 Pa, C. 760.0 atm, D. 760.0 bar

6-1-2. What is the pressure due to a vertical column of water that is 760 mm long? (use the following densities: water 1.00 g/mL, Hg is 13.6 g/mL)
A. 7.6 x 10² Torr, B. 1.0 x 10⁵ Torr, C. 7.4 x 10^-2 atm

6-1-3. A gas bulb is connected to an open-end mercury manometer and the liquid level in the arm connected to the gas bulb is found to be 15.0 cm lower than in the arm that is open to the atmosphere. The prevailing barometric pressure is 755 mm Hg. What is the pressure of the gas in the bulb?
A. 905 Torr, B. 770 Torr, C. 740 Torr, D. 605 Torr

6-1-4. A gas bulb is connected to an open-end mercury manometer and the liquid level in the arm connected to the gas bulb is found to be 20.0 mm higher than in the arm that is open to the atmosphere. The prevailing barometric pressure is 758 mm Hg. What is the pressure of the gas in the bulb?
A. 778 Torr, B. 760 Torr, C. 756 Torr, D. 738 Torr

5-13 Write net ionic equations to represent acid-base reactions

2008-12-18T12:10:00.000-08:00

5-13-2. What is the net ionic equation for the reaction between
HF(aq) and Ca(OH)₂(aq)?
A. 2 HF(aq) + Ca(OH)₂(aq) → 2 H₂O(l) + CaF₂(s)
B. 2 H⁺(aq) + 2 F^-(aq) + Ca²⁺(aq) + 2 OH^-(aq) → 2 H₂O(l) +
2F^-(aq) + Ca²⁺(aq)
C. 2 HF(aq) + Ca²⁺(aq) + 2 OH^-(aq) → 2 H₂O(l) + 2F^-(aq) + Ca²⁺(aq)
D. 2 HF(aq) + Ca²⁺(aq) + 2 OH^-(aq) → 2 H₂O(l) + CaF₂(s)

5-13-3. What is the net ionic equation for the reaction between
HNO₃(aq) and NH₃(aq)?
A. HNO₃(aq) + NH₃(aq) → NH₄NO₃(aq)
B. H⁺(aq) + NO₃^-(aq) + NH₃(aq) → NH₄⁺(aq) + NO₃^-(aq)
C. H⁺(aq) + NH₃(aq) → NH₄⁺(aq)

5-13-4. What is the net ionic equation for the reaction between
Mg(OH)₂ in milk of magnesia with HCl (in stomach acid)? The complete formula equation is:
Mg(OH)₂ + 2 HCl → MgCl₂ + 2 H₂O
A. Mg²⁺ + 2 OH^- + 2 H⁺ + 2 Cl^- → Mg²⁺ + 2 Cl^- + 2 H₂O
B. Mg(OH)₂ + 2 H⁺ + 2 Cl^- → Mg²⁺ + 2 Cl^- + 2 H₂O
C. H⁺ + OH^- → H₂O
D. Mg(OH)₂ + 2 H⁺ → Mg²⁺ + 2 H₂O

5-11 Describe strong and weak bases

2008-12-18T07:17:00.000-08:00

5-11-1. Which of the following best represents the dissolution of gaseous ammonia (NH₃) in water?
A. NH₃(g) → NH₃(aq)
B. NH₃(g) + H₂O(l) → NH₄⁺(aq) + OH^-(aq)
C. NH₃(g) + H₂O(l) → NH₄OH(aq)
D. NH₃(aq) + H₂O(l) → NH₄⁺(aq) + OH^-(aq)

5-11-2. Which of the following is a weak base?
A. NaOH, B. Mg(OH)₂, C. K₂O, D. NH₃

5-9 Describe strong and weak acids

2008-12-17T08:10:00.000-08:00

5-9-1. Which of the following is a strong acid?
A. H₂SO₄, B. HC₂H₃O₂, C. HCOOH, D. HNO₂

5-9-2. Match HCl and HF to the pictorial representations of aqueous solutions shown in Figures A and B.

A. A-HCl, A-HF
B. B-HCl, B-HF
C. A-HCl, B-HF
D. A-HF, B-HCl

5-10 Write chemical equations to represent ionization of acids in water

2008-12-16T13:04:00.000-08:00

5-10-1. Which of the following best represents the ionization of nitric acid in water?
A. HNO₃(aq) → H(aq) + NO₃(aq)
B. HNO₃(aq) → H⁺(aq) + NO₃^-(aq)
C. HNO₃(aq) → H⁺(aq) + N^3-(aq) + 3 O^2-(aq)
D. HNO₃(aq) → H⁺(aq) + N^3-(aq) + O₃^-(aq)

4-6 Determine amount of element present in a compound

2008-12-15T08:15:00.000-08:00

4-6-1. What is the percentage by mass of oxygen in CO₂?
A. 27.29%, B. 66.67%, C. 72.71%

5-3 Describe the dissolution of ionic and molecular compounds in water

2008-12-15T07:54:00.000-08:00

5-3-1. Which figure below best represents an aqueous solution of CaCl₂?

5-3-2. Which figures below best represent aqueous solutions of HF and HCl?
A. A for both,
B. B for both,
C. HF-B, HCl-A,
D. HF-A, HCl-B

5-3-3. Which of the following best represents the dissolution of
CaCl₂(s) in water?
A. CaCl₂(s) → Ca²⁺(aq) + 2 Cl^-(aq)
B. CaCl₂(s) → CaCl₂(aq)
C.CaCl₂(s) → Ca²⁺(aq) + Cl₂^2-(aq)

5-3-4.Which of the following best represents the dissolution of methanol, CH₃OH(l), in water?
A. CH₃OH(l) → CH₃OH(aq)
B. CH₃OH(l) → CH₃⁺(aq) + OH^-(aq)
C. CH₃OH(l) → CH₃O^-(aq) + H⁺(aq)
D. CH₃OH(l) + H₂O(l) → CH₃OH₂⁺(aq) + OH^-(aq)

5-2 Differentiate solution, colloids, suspensions, and coarse mixtures

2008-12-15T07:38:00.000-08:00

5-2-1. If a medicine bottle has a "shake well before using" label, it most likely contains......
A. a solution, B. a colloid, C. a suspension

5-2-2. Which of the following is a coarse mixture?
A. air, B. 18K gold, C. gasoline, D. salad

4-10 Determine amount of unreacted excess reactant

2008-12-12T12:01:00.000-08:00

4-10-1. Consider the reaction: N₂ + 3 H₂ → 2 NH₃ For a mixture of 2.00 mol N₂ and 3.00 mol H₂, How much of the excess reactant would remain if the limiting reactant is consumed?
A. 0.500 mol, B. 1.00 mol, C. 2.00 mol, D. 4.00 mol

5-7 Predict if a precipitation reaction could occur

2008-12-11T13:34:00.000-08:00

5-7-1. Precipitation is expected from which mixture?
A. Na₂CO₃(aq) + KNO₃(aq)
B. AgNO₃(aq) + CaCl₂(aq)
C. Neither
D. Both

5-7-2. A student is given two test tubes and is told that one contains NaCl(aq), while the other test tube contain Ba(NO₃)₂(aq). Which precipitating reagent, if added to both test tubes would allow the student to determine their contents?
A. AgNO₃(aq), B. K₂SO₄(aq), C. neither, D. both

5-8 Write net ionic equations for precipitation reactions

2008-12-09T11:11:00.000-08:00

5-8-1. What is the net ionic equation for the precipitation reaction that occurs when K₂SO₄(aq) and Pb(NO₃)₂ are mixed?
A. K⁺(aq) + NO₃^-(aq) → KNO₃(s)
B. Pb⁺(aq) + SO₄^-(aq) → PbSO₄(s)
C. Pb²⁺(aq) + SO₄^2-(aq) → PbSO₄(s)

5-8-2. What is the net ionic equation for the precipitation reaction that occurs when Na₂CO₃(aq) and AgNO₃ are mixed?

A. Na⁺(aq) + NO₃^-(aq) → NaNO₃(s)

B. Ag⁺(aq) + CO₃^2-(aq) → Ag₂CO₃(s)

C. Ag²⁺(aq) + CO₃^2-(aq) → AgCO₃(s)

D. 2 Ag⁺(aq) + CO₃^2-(aq) → Ag₂CO₃(s)

5-8-CML. Write the net ionic equation for the following chemical reaction: Sodium sulfate reacts with barium acetate to form barium sulfate and sodium acetate.

5-5 Classify ionic compounds as soluble or insoluble in water

2008-12-09T11:04:00.000-08:00

5-5-1. Which of the following is insoluble in water?
A. Na₂CO₃, B. MgSO₄, C. PbCl₂, D. CaS

5-5-2. Which of the following is insoluble in water?
A. CuCl₂, B. Hg₂Cl₂, C. HgBr₂, D. Ca(NO₃)₂

5-5-3. Which of the following is soluble in water?
A. MgCO₃, B MgF₂, C. Mg(OH)₂, D. MgSO₄

5-5-JJW. Which of the following salts is insoluble in water?
A. NaNO₃, B. Fe(OH)₃, C. AgClO₄, D. MgSO₄

5-4 Classify solutions as saturated, supersaturated or unsaturated

2008-12-09T10:53:00.000-08:00

5-4-1. If figure A represents a saturated solution, figure B can be described as...
A. unsaturated and less dilute
B. unsaturated and less concentrated
C. supersaturated and more concentrated

5-4-2. The solubility of sodium nitrate in water is 85 g NaNO₃ per
100 g of water at 20^oC. At 50^oC, the solubility is 115 g NaNO₃ per 100 g of water. A saturated solution of NaNO₃ is prepared by mixing 150 g of NaNO₃ and 100 g of water at 20^oC. When this mixture is heated to 50^oC, the resulting solution will be...
A. unsaturated, B. still saturated, C. supersaturated

5-1 Differentiate solutions from compounds

2008-10-23T08:14:00.000-07:00

5-1-CML. Categorize the following as solution(S) or compound (C): Salt, Salt water, olive oil, Coffee, 0.5 M NaOH, Rubbing alcohol, Saline, Milk, 14K gold, Ketchup

4-1 Distinguish between masses of individual atoms and average masses

2008-10-23T08:09:00.000-07:00

4-1-1. The mass of one atom of Mg-26 is closest to
A. 24.3 u
B. 24.0 u
C. 26.0 u
D. 12.0 u

4-1-2. In a ficticous world, element X has only two isotopes: ⁷⁷X with a mass of 77.0 u and ⁷⁸X, with a mass of 78.0 u. The relative abundance of the heavier isotope is 30.0%. The average mass of the X atoms is....
A.77 u
B.77.3 u
C.77.5 u
D.78 u

4-1-3. In a fictious world, element Z has only two isotopes: ³⁵Z with a mass of 35.00 u and ³⁷Z, with a mass of 37.00 u. What is the relative abundance of the lighter isotope if the average mass is 35.8u.
A.40.0%
B.50.0%
C.60.0%

3-13. Describe intermolecular forces and relate to molecular structure and properties

2008-10-23T07:31:00.000-07:00

3-13-1. Which type of intermolecular forces is present between any pair of molecules?
A. London dispersion forces
B. dipole-dipole interaction
C. hydrogen bonding interaction

3-13-2. For which pair of molecules does dipole-dipole interaction occur?
A. H₂O and CO₂
B. H₂O and HF
C. CO₂ and CO₂
D. CH₄ and CO₂

3-13-3. For which pair of molecules is London Dispersion strongest?
A. H₂O and H₂O
B. H₂O and H₂S
C. H₂S and H₂S

3-13-4. How many atoms in the acetic acid molecule (CH₃COOH) are capable of hydrogen bonding interaction with water molecules?
A. 1
B. 2
C. 3
D. 4

3-13-5. Which of the following is least soluble in water?
A. NH₃
B. HF
C. CH₄

3-13-6. Which of the following explains why the melting point of iodine is higher than that of iodine chloride?

3-13-7. Which of the following has the lowest boiling point?
A. O₂
B. F₂
C. Cl₂

3-13-ALD. Which of the following has the highest boiling point?
A. N₂O
B. N₂
C. NH₃
D. There is not enough information to answer this question

3-12 Predict molecular polarity

2008-10-23T06:56:00.000-07:00

3-12-1. Which of the following is/are true?

1) A nonpolar molecule can have polar bonds.
2) A molecule with no polar bonds is nonpolar.

A. 1 only
B. 2 only
C. both
D. neither

3-12-2. Which of the following molecules is polar?
A. H₂O
B. BF₃
C. CH₄
D. PF₅

3-14 Use valence bond theory to explain molecular geometry

2008-09-15T17:09:00.000-07:00

3-14-1. What type of orbital hybridization explains the linear electronic geometry around an atom with a steric number of 2?
A. sp
B. sp²
C. sp³
D. sp³d
E. sp³d²

3-14-2. What is the hybridization of the valence orbitals of the carbon atom in the structure below?
A. sp
B. sp²
C. sp³
D. sp³d

3-14-3. In the structure below, the sigma bond between which two atoms is due to an sp²-to-sp² overlap?
A. C and O
B. C and N
C. N and H

3-14-4. In the structure below, which of these bonds is the longest?
A. the C-C bond
B. the C=C bond
C. the C-H bond

3-14-ALD. Consider the Lewis structure of methylisothiocyanate. State the hybridization of the indicated carbon atom.
A. sp³
B. sp
C. sp²
D. sp³d

4-2 Define mole and Avogadro number

2008-09-15T16:56:00.000-07:00

4-2-1. Which of these is false?
A. A mole of atoms contains exactly 6.02x10²³ atoms.
B. The exact number of molecules in one mole of molecules is equal to Avogadro's number.
C. The exact number of ions in one mole of ions is equal to Avogadro's number.
D. None of the above.

4-2-2. Which has more atoms?
A. 1 mole of Mg-24
B. 1 mole of Mg-26
C. neither

4-2-3. Which has more molecules?
A. 1 mole of SO₂
B. 1 mole of SO₃
C. neither

4-4 Count atoms and molecules in molecular compounds or ions in an ionic compound

2008-09-15T16:27:00.000-07:00

4-4-1. How many atoms of oxygen are in 1.50 mol CO₂?
A. 1.50 mol
B. 0.300 mol
C. 3.00 mol
D. 0.750 mol

4-4-2. How many cations are in 2.00 mol Na₃PO₄?
A. 0.667 mol
B. 6.00 mol
C. 0.500 mol
D. 1.00 mol

4-3 Relate mole count to individual count

2008-09-15T16:15:00.000-07:00

4-3-1. How many atoms of carbon are in a 2.50 mol sample of carbon?
A. 1.51x10²⁴
B. 30.0
C. 4.15x10^-22

4-3-2. How many moles of O₂ molecules are in a sample containing 3.0x10²² O₂ molecules?
A. 2.0 mol
B. 1.06x10^-21 mol
C. 0.50 mol

3-9 Recognize exceptions to the octet/duet rule

2008-09-15T16:05:00.000-07:00

3-9-1.Which of the following atoms can have more than an octet of valence electrons when it shares electrons with other atoms?
A. S
B. N
C. C
D. H

3-9-2. In which of the following atoms must have an octet when sharing electrons with other atoms?
A. N
B. B
C. P
D. none of these

3-9-ALD. In the molecule HSF₅, which atom(s) violate the octet rule?
A. H
B. S
C. F
D. Both H and S

6-3 Determine molar mass of a gas from density, Pressure, and Temperature data

2008-09-15T15:42:00.000-07:00

6-3-ALD. What is the density of Freon-11 (CFCl₃) at 120°C and 1140 torr?
A. 1.59 x 10⁴ g/L
B. 20.9 g/L
C. 6.39 g/L
D. 22.4 g/L

6-3a-ALD. An evacuated 63.8 mL glass bulb is filled with a gas at 295K and 0.983 atm. The mass of this gas is 0.104 g. What is the identity of this gas?
a. N₂
b. Ne
c. Ar
d. O₂

6-2 Relate Pressure, Volume, Temperature, and moles of gas

2008-09-15T15:30:00.000-07:00

6-2-1. What is the mass of a 248.0 mL sample of oxygen gas at 100.00oC and 0.500 atm?
A. 0.130 g, B. 0.484 g, C. 2.03 g

6-2-3. Which of the following gas samples has the smallest volume at 300K and 125 Torr?
A. 1.00 mol H₂, B. 2.00 mol He, C. 2.00 mol CH₄

6-2-4. Which of the following gas samples has the smallest volume at 300K and 125 Torr?
A. 1.00 g H₂, B. 2.00 g He, C. 2.00 g CH₄

6-2-ALD. A sample of Freon-12 (CF₂Cl₂) occupies 25.5L at 25°C and 153.3 kPa. Find its volume at STP.
A. 22.4L
B. 0.00L
C. 3580L
D. 35.5L

5-6 Recognize chemical equations for precipitation reactions

2008-09-11T12:13:00.000-07:00

5-6-1. Which of the following is a precipitation reaction?
A. Na₂CO₃(aq) + 2 AgNO₃(aq) → Ag₂CO₃(s) + 2 NaNO₃(aq)
B. 2 Mg(s) + O₂(g) → 2 MgO(s)
C. HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)

5-6-JJW. Which of the following represents a precipitation reaction?
A. KOH + HCl → H₂O + KCl
B. KCl + AgNO₃ → AgCl + KNO₃
C. 2 KClO₃ → 2 KCl₃ + 3 O₂

5-12 Write chemical equations to represent acid-base reactions

2008-09-11T11:58:00.000-07:00

5-12-1. QUESTION: What is chemical equation for the neutralization of stomach acid, HCl, by milk of magnesia, Mg(OH)₂?
A. HCl + Mg(OH)₂ → HMg + Cl(OH)₂
B. 2 HCl + Mg(OH)₂ → 2 HOH + MgCl₂
C. HCl + Mg(OH)₂ → H₂O + MgCl
D. HCl + Mg(OH)₂ → H₂O + MgHCl

5-12-2. What is the chemical equation for the neutralization of nitric acid, HNO₃, by calcium oxide (CaO)?
A. HNO₃ + CaO → HO + CaNO₃
B. 2 HNO₃ + CaO → H₂O + Ca(NO₃)₂
C. HNO₃ + CaO → NO₄ + CaH
D. 2 HNO₃ + CaO → H₂O + CaNO₃

5-12-JJW. What is the correct equation for the complete neutralization of sulfuric acid by potassium hydroxide?
A. H₂SO₄ + KOH → H₂O + KSO₄
B. H₂SO₄ + KOH → H₂O + KHSO₄
C. H₂SO₄ + KOH → H₂O + K₂SO₄
D. H₂SO₄ + 2 KOH → 2 H₂O + K₂SO₄

5-17 Solve stoichiometry problems involving solutions

2008-09-11T07:28:00.000-07:00

5-17-1. Consider the neutralization of Mg(OH)₂(s) by HCl(aq).

Mg(OH)₂(s) + 2 HCl(aq) → MgCl₂(aq) + 2 H₂O(l)

What volume of 0.200M HCl(aq) is required to neutralize 0.200 mol Mg(OH)₂?
A. 500.0 mL, B. 1.00 L, C. 2.00 L, D. 4.00 L

5-17-2. Consider the neutralization of sulfuric acid by sodium hydroxide.

H₂SO₄(aq) + 2 NaOH(aq) → 2 H₂O(l) + Na₂SO₄

What if a 25.00 mL sample of sulfuric acid solution is titrated with 0.500 molar sodium hydroxide solution. If 25.00 mL of the base was required to reach the endpoint,what is the molarity of the sulfuric acid solution?
A. 0.125M, B. 0.250M, C. 0.500M, D. 1.00M

5-17-JJW. What mass of silver chloride will be formed if 50.0 mL of 0.750 molar silver nitrate is mixed with 70.0 mL of 0.500 molar sodium chloride?
A. 2.04 g
B. 5.02 g
C. 5.37 g
D. 6.37 g

5-15 Calculate molarity of solutions and of ions in solution

2008-09-11T07:12:00.000-07:00

5-15-1. What is the molarity of a solution if a 2.0 L sample contains 3.0 mol NaOH?
A. 1.5 M, B. 0.67 M, C. 6.0 M

5-15-3. What is the molar concentration of chloride ions in 0.30M BaCl₂?
A. 0.30M, B. 0.15M, C. 0.60M, D. 0.20M

5-15-4. What is the molar concentration of sodium ions in a solution that is 0.20M in NaCl and 0.30M in Na₂SO₄?
A. 0.50M, B. 0.25M, 0.70M, 0.80M

5-15-5. A solution is prepared by mixing 10.0 mL of 0.100M NaNO₃, 20.0 mL of 0.300M Ca(NO₃)₂, and enough water to bring the total volume up to 50.0 mL. What is the molar concentration of nitrate ions in the resulting solution?
A. 0.200M, B. 0.260M, C. 0.130 M, D. 0.700 M

5-15-JJW. What is the molarity of a solution of 15.0 g of lithium perchlorate in 4.50 x 10² mL of water?

A. 0.0634 M
B. 0.313 M
C. 3.54 M
D. 63.4 M

1A-8 Solve problems dealing with measurements of physical properties (mass, volume, density, temperature, heat, heat capacity, solubility)

2008-09-10T09:04:00.000-07:00

1A-8-1. What is the density of a liquid if a 25.0 mL sample of the liquid has a mass of 20.00 g?
A. 0.8 g/mL, B. 0.800 g/mL,
C. 1.25 g/mL, D. 1.3 g/mL

1A-8-2. Glacial acetic acid is a liquid with a density of 1.06 g/mL. If an experiment calls for 5.0 g of acetic acid, what volume of glacial acetic acid do we need?
A. 4.7 mL, B. 4.72 mL, C. 0.21 mL, D. 0.212 mL

1A-8-3. Illustrated below is a commonly used procedure for determining the density of an irregularly shaped, water-insoluble solid. The solid is weighed, then submerged in water. Suppose the solid weighed 48.0 g and the water level in the cylinder rose from 20.9 mL to 26.9 mL The density of the solid is...
A. 2.0 g/mL, B. 2.00 g/mL,
C. 8.0 g/mL, D. 8.00 g/mL

1A-6 Convert temperature readings

2008-08-27T15:30:00.000-07:00

1A-6-1. What temperature reading on the Fahrenheit scale corresponds to 20.0^oC?
A. 20.0^oF, B. 68.0^oF, C. 36.0^oF, D. -6.67^oF

1A-6-2. What temperature reading on the Celsius scale corresponds to 20.0^oF?
A. 20.0^oC, B. 68.0^oC, C. 36.0^oC, D. -6.67^oC

1A-6-3. At what temperature are the Celsius and Fahrenheit readings equal?
A. -40^o, B. 32^o, C. 100^o, D. 212^o

1A-6-4. What is the Kelvin temperature equivalent to 25.00^o C?
A. 298K, B. 298.15K, C. -248.15K

1A-6-5. What is the Kelvin temperature equivalent to 50.00^o F?
A. 323.15K, B. 283.15K, C. 263.15K, D. 395.15K

1-31 Construct a balanced chemical equation

2008-08-20T08:57:00.000-07:00

1-31-1. Which of the following is not a balanced chemical equation?
A. 2 H₂ + O₂ → 2 H₂O
B. 4 H₂ + 2 O₂ → 4 H₂O
C. Both A and B
D. None of the above

1-31-2. Which of the following is the balanced chemical equation for the following reaction: Mg + O₂ → MgO
A. Mg + O → MgO
B. Mg + O₂ → MgO + O
C. Mg₂ + O₂ → 2 MgO
D. 2 Mg + O₂ → 2 MgO

1-31-3. Consider the following chemical equation where coefficients are represented by the letters w,x,y, and z:

w Al₂O₃ + x H₂SO₄ → y Al₂(SO₄)₃ + z H₂O

If w=1, then which of these is true?

A. y=2, B. z=3, C. x=6

1-31-4. Consider the combustion of propane: C₃H₈ + O₂ → CO₂ + H₂O(unbalanced)Using the smallest set of whole numbers, the sum of the coefficients in the balanced chemical equation is:
A. 7, B. 9, C. 12, D. 13

1-31-5. Consider the pictorial representation of a chemical change shown below. Using the smallest set of whole numbers, the coefficient of C₂H₂ in the balanced chemical equation for this reaction is...
A. 1, B. 2, C. 3, D. 4

1-31-6. Consider the pictorial representation of a chemical change shown below. Using the smallest set of whole numbers, the coefficient of NH₃ in the balanced chemical equation for this reaction is...
A. 2, B. 3, C. 4, D. 6

1-31-7. Consider the following observations of a chemical change: A small amount of orange-red solid is heated in a test tube. A little explosion occurred and a green powder was obtained. The mass of the green solid was found to be less than that of the original orange-red solid. Which of the following chemical equations is consistent with the observations above?
A. Mg(s) + O₂(g) → 2 MgO(s)
B.(NH₄)₂Cr₂O₇(s) → 2 N₂(g) + Cr₂O₃(s) + 4 H₂O(g)
C. 2 HgO(s) → 2 Hg(l) + O₂(g)
D. Pb(NO₃)₂(aq) + 2 NaCl(aq) → PbCl₂(s) + 2 NaNO₃(aq)

1-12 Describe how isotopes can be separated

2008-08-20T08:42:00.000-07:00

1-12-1. Consider a gas containing 0.7% ²³₅UF₆ and 99.3% ²³₈UF₆. If the gas is contained in chamber A, as illustrated below, and is allowed to escape through a pinhole into vacuum chamber B, the percentage of ²³₅UF₆ in the gas that initially emerges in chamber B will be...
A. higher than 0.7%,
B. lower than 0.7%,
C. still 0.7%

1-12-2. A sample of H₂ molecules, containing protium (¹H) and deuterium (²H) isotopes, is injected into a mass spectrometer. How many signals due to H₂⁺ ions can we expect to observe?
A. 0, B. 1, C. 2, D. 3

3-7 Determine formal charges

2008-08-11T13:20:00.000-07:00

3-7-1. Which of the Lewis structures shown below for azide ion (N₃^-) has a nitrogen atom with a formal charge of -2?
A. Structure I only
B. Structure II only
C. Both structures
D. neither structure

3-7-2. Which of the Lewis structures shown below has zero formal charges for all the atoms?
A. Structure I
B. Structure II
C. Structures III
D. Structure IV

3-7-JJW. What are the formal charges on the O,N, and O in the nitrite ion?
A. -1, +1, -1
B. 0, -1, 0
C. -1, 0, 0
D. -1, -1, +1

3-7-ALD. What is the formal charge of N in the NO₃^- ion?
A. +1
B. +5
C. -1
D. 0

3-6 Recognize and differentiate resonance and isomeric structures

2008-08-11T13:16:00.000-07:00

3-6-1. Which of the structures shown below are resonance structures?
A. Structures I and II,
B. Structures II and IV,
C. Structures I and III,
D. Structures II and III

1A-7 Convert temperature differences or changes

2008-08-11T12:08:00.000-07:00

1A-7-1. If the temperature increases by 20.0 degrees Celsius, by how much did it increase in degrees Fahrenheit?
A. 36.0°, B. 68.0°, C. 6.67°, D. 20.0°

1A-7-2. During a chemical reaction, the temperature of a mixture dropped by 10.0°C. By how much did the temperature drop in Kelvin?
A. 10.0K, B. 283.15K, C. 263.15K

1A-5 Convert units

2008-08-11T11:57:00.000-07:00

1A-5-1. Given: 1 inch is exactly equivalent to 2.54 cm. A measurement of 7.00 cm is equivalent to how many inches?
A. 2.76 in, B. 3 in, C. 17.8 in, D. 20 in

1A-5-2. Given: 1 inch is exactly equivalent to 2.54 cm, and 12 inches is exactly 1 foot. A measurement of 7.0 cm is equivalent to how many feet?
A. 1.48 ft, B. 1.5 ft, C. 0.23 ft, D. 0.230 ft

1A-5-3. A measurement of 2.50 mm is equivalent to ...
A. 2.50x10⁶ nm, B. 2.50x10^-9 nm, C. 2.50x10^-6 nm, D. 2.50x10⁹ nm

1A-5-4. A car is traveling at a speed of 40.0 km hr^-1. How fast is the car moving in km min^-1?
A. 2.40x10³ km min^-1, B. 6.67x10^-1 km min^-1, C. 1.50 km min^-1

1A-5-5. The density of air is 1.29x10^-3 g/L. What is the density of air in mg/mL?
A. 1.29x10^-3 mg/mL, B. 1.29 mg/mL, C. 1.29x10^-6 mg/mL

1A-5-6. The area of a circle is found to be 2.4 cm². What is the area in m²?
A. 2.4x10² m², B. 2.4x10^-2 m², C. 2.4x10^-4 m², D. 5.8x10⁴ m²

1-32 Classify and predict products of simple reactions

2008-08-11T11:11:00.000-07:00

1-32-1. Which of the following is a decomposition reaction?
A. 2 CO(g) + O₂(g) → 2 CO₂(g)
B. Mg(s) + 2 HCl(aq) → MgCl₂(aq) + H₂(g)
C. Ba(OH)₂(aq) + H₂SO₄(aq) → 2 H₂O(l) + BaSO₄(s)
D. 2 H₂O₂(aq) → 2 H₂O(l) + O₂(g)

1-32-2. What is the salt produced by the neutralization reaction of magnesium hydroxide, Mg(OH)₂, and hydrochloric acid, HCl?
A. MgCl, B. MgCl₂, C. HOH, D. none of these

1-32-3. Which of the following is a correct chemical equation for a combination reaction between a metallic element and nonmetallic element?
A. Mg(s) + N₂(g) → MgN₂(s),
B. Mg(s) + O₂(g) → MgO₂(s)
C. Mg(s) + N(g) → MgN
D. None of these

1-32-4. Which of the following chemical reactions is not a redox reaction?
A. C(s) + O₂(g) → CO₂(g)
B. Cl₂(g) + 2 KBr(aq) → 2 KCl(aq) + Br₂(l)
C. 2 KClO₂(s) → 2 KCl(s) + 3 O₂(g)
D. NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(l)

1-32-5. Which of the following chemical reactions is a redox reaction?
A. NH₃(g) + HCl (g) → NH₄Cl(s)
B. CaCO₃(s) → CaO(s) + CO₂(g)
C. 2 CaO(s) → 2 Ca(s) + O₂(g)
D. Ag⁺(aq) + Cl^-(aq) → AgCl(s)

1-29 Describe and differentiate physical and chemical changes/properties

2008-08-11T10:42:00.000-07:00

1-29-1. Consider the pictorial representation shown below for a process at the atomic/molecular level. Which process involves a chemical change?
A. 1 only, B. 2 only, C. both, D. neither

1-29-2. Consider the pictorial representation shown below for a process at the atomic/molecular level. Which process does not involves a chemical change?

1-29-3. Which of the pictorial representations best accounts for the conversion of water from liquid to steam?

1-29-4. Which of the following observations is a definite sign that a chemical change has occurred?
A. Mixing a blue-colored liquid with a yellow-colored liquid, yields a green-colored mixture.
B. Mixing a blue-colored liquid with a colorless liquid yields a yellow-colored liquid
C. Neither
D. Both

1-29-5.Which of the following observations implies that a chemical change has definitely not occurred?
A. Mixing two colorless liquids yields a colorless liquid.
B. A piece of paper, held next to a flame, catches fire and leaves a black residue.
C. Both
D. Neither

1-28 Read and write formulas of acids

2008-08-11T10:35:00.000-07:00

1-28-1. Which of the following is sulfurous acid?
A. H₂SO₄, B. H₂SO₃, C. H₂S

1-28-2. Which of the following is another name for hydrogen cyanide (HCN)?
A. hydrocyanic acid, B. cyanic acid, C. cyanous acid

1-27 Read and write formulas of compounds containing polyatomic ions

2008-08-11T10:19:00.000-07:00

1-27-1. Which of the following is the correct formula for sodium phosphate?
A. NaP, B. NaPO₃, C. Na₃PO₄, D. Na₃(PO₄)₂

1-27-2. Which of the following is the correct formula for ammonium sulfide?
A. (NH₄)₂S, B. NH₄SO₃, C. (NH₃)₂SO₄

1-27-3.Which of the following is the correct formula for iron(III) sulfate?
A. Fe₃ S, B. FeSO₄ , C. Fe₂(SO₃)₃ , D. Fe₂(SO₄)₃

1-27-4.Which of the following is the correct formula for potassium hydrogen phosphate?
A. KHPO₄, B. K₂HPO₄, C. KH₂PO₄

1-27-5. Which of the following is the correct name for K₂CO₃?
A. dipotassium carbon trioxide, B. potassium carbide,
C. dipotassium carbonate, D. potassium carbonate

1-27-6. Which of the following is the correct name for FeSO₄?
A.iron(I) sulfate, B. iron(II) sulfate, C.iron(III) sulfite, D. iron sulfite

1-27-7. Which of the following is the correct name for BaO₂?
A. barium oxide, B. barium peroxide,
C. barium dioxide, D. barium(IV) oxide

1-26 Read and write formulas of binary compounds

2008-08-11T10:06:00.000-07:00

1-26-1. Which of the following is the correct name for PCl₅?
A. phosphorus chloride, B. phosphorus chlorine,
C. phosphorus pentachlorine, D. phosphorus pentachloride

1-26-2. Which of the following is the correct name for MgCl₂?
A. magnesium chloride, B. magnesium dichloride,
C. magnesium chlorine, D. magnesium dichlorine

1-26-3. Which of the following is the correct formula for dinitrogen tetroxide?
A. NO, B. N₂O₃, C. N₂O₄, D. NO₂

1-26-4. Which of the following is the correct name for Na₂S?
A. sodium sulfide, B. disodium sulfide,
C. sodium sulfite, D. sodium sulfate

1-26-5. Which of the following is the formula for iron(III) sulfide?
A. FeS, B. Fe₃S, C. Fe₂S₃, D. Fe₃S₂

1-26-6. Which of the following is the formula for cobalt(II) chloride?
A. CoCl, B. CoCl₂, C. Co₂Cl, D. Co₂Cl₂

1-26-7. Which of the following is correct name for CuCl₂?
A. copper(II) chloride, B. copper(I) chloride,
C. copper chloride(II), D. copper(I) dichloride

1-3 Describe separation techniques for samples of matter

2008-08-11T09:58:00.000-07:00

1-3-1. Which technique is best used to separate pure water from saltwater?
A. filtration, B. evaporation, C. distillation

1-3-2. What sequence of laboratory procedures can be used to separate salt from a sand-and-salt mixture?
A. extraction, filtration, evaporation
B. filtration, extraction, evaporation
C. evaporation, filtration, extraction
D. extraction, evaporation, filtration

1-2 Differentiate physical states of matter in terms of shape, volume (compressibility), intermolecular distances, molecular motion

2008-08-11T09:46:00.000-07:00

1-2-1. For which of the following are the atoms, on average, farthest from one another?
A. air, B. gasoline, C. copper wire

1-2-2.Water is made up of molecules. For which physical state is the motion of the water molecules most restricted?
A. solid (ice), B. liquid, C. gas(steam)

1-2-3. What physical state of matter is being described by the following phrase: "particles are as close to one another as possible and unable to move"
A. solid, B. liquid, C. gas, D. none of these

1-2-4. Consider the pictorial representation shown below for a change in physical state at the molecular level. The picture best represents which of these changes:
A. evaporation, B. melting, C. sublimation, D. condensation

1-1 Differentiate hypothesis, observation, theory, and law

2008-08-11T09:41:00.000-07:00

1-1-1. Consider the following statements: "A drop of alcohol on a lab bench disappears after 5 minutes. The drop disappeared because molecules of alcohol moved apart and spread into the entire room." These statements, respectively, are:
A. hypothesis and theory, B. observation and hypothesis
C. observation and theory, D. law and theory

1-1-2. Consider the following statement: "Matter expands when heated." This statement is an example of :
A. a law, B. a theory, C. a hypothesis, D. an observation

1-1-3. Which of these statements is/are true?
1) It is good to do research on a problem or question before formulating a hypothesis.
2) It is not possible to prove a theory.
A. 1 only, B. 2 only, C. both, D. neither

1-30 Identify reactants and products of a chemical reaction

2008-08-04T08:15:00.000-07:00

1-30-1. A mixture contains 25.0 g of substance X and 10.0 g of substance Y. A few minutes later, due to a chemical change, it is found that the mixture now contains 30.0 g of substance X and 5.0 g of substance Y. For the reaction described here...
A. X is the reactant and Y is the product
B. Y is the reactant and X is the product
C. Both X and Y are reactants
D. Both X and Y are products

1-30-2. Consider the pictorial representation of a chemical change shown below. Which of the following is not a product of the reaction?
A. C₂H₂, B. H₂O, C. CO₂

1-30-3. Consider the chemical equation for the hydrogenation of acetylene:
C₂H₂ + 2H₂ → C₂H₆
Which of these is the formula of a reactant in this reaction?
A. C₂H₂, B. 2H₂, C. C₂H₆

1-4 Differentiate elements, compounds, and mixtures

2008-07-16T11:44:00.000-07:00

1-4-1. What type of matter cannot be separated into two or more distinct components?
A. element, B. compound, C. mixture, D. pure substance

1-4-2. A naturally-occurring sample of matter most likely consists of...
A. a single element, B. a single compound
C. a mixture, D. a pure substance

1-4-3. A sample of matter is heated and found to start melting at 75.0^oC. While melting, the sample temperature continues to rise to about 85.0^oC. This matter is most likely...
A. an element, B. a compound, C. a mixture

1-4-4. Samples A, B, and C appear to be identical. Each sample is found to melt sharply at 122^oC. However, a mixture of sample A and B is found to melt from 115-120^oC, while a mixture of sample A and C is found to melt sharply at 122^oC. Which of the following is true?

A. Samples A and B are composed of the same substance
B. Samples A and C are composed of the different substances
C. A mixture of B and C will have a sharp melting point
D. None of the above

1-24 Write formulas of molecular and ionic compounds based on a description of the atoms or ions that make up a formula unit

2008-07-10T12:06:00.000-07:00

1-24-1. What is the formula of an ionic compound consisting of Ca²⁺ and Cl^- ions?
A. CaCl, B. Ca₂Cl, C. CaCl₂, D. Ca₂Cl₂

1-24-2. What is the formula of an ionic compound consisting of Na⁺ and CO₃^2- ions?

A. NaCO₃, B. Na₂(CO₃)₂, C. NaCO, D. Na₂CO₃

1-24-3. What is the formula of an ionic compound consisting of Ca²⁺ and CO₃^2- ions?

A. CaCO₃, B. Ca₂(CO₃)₂, C. CaCO, D. Ca₂CO₃

1-24-4. What is the formula of an ionic compound consisting of Mg²⁺ and PO₄^3- ions?

A. Mg₂PO₃, B. Mg₃(PO₄)₂, C. Mg₃PO₂, D. MgPO₄

1-24-5. A molecule of fructose consists of six carbon atoms, twelve hydrogen atoms, and six oxygen atoms. The formula of fructose is...
A. C₆H₁₂O₆, B. CHO, C. CH₂O

1-24-6. A molecule of acetic acid consists of four hydrogen atoms, two carbon atoms, and two oxygen atoms. Which of these cannot possibly be the formula of acetic acid?
A. H₄C₂O₂, B. H₂CO, C. HC₂H₃O₂, D. CH₃COOH

1-24-7. Which of these is not the formula of the compound represented by the figure below, if blue spheres represent carbon atoms, white spheres represent hydrogen atoms and red sphere represents an oxygen atom?

A. CHO, B. C₂H₆O, C. C₂H₅OH, D. CH₃CH₂OH

3-11 Describe molecular geometry using VSEPR

2008-06-26T09:44:00.000-07:00

3-11-1. Which of the structures below represent a linear molecule?
A. 1 and 2
B. 2 and 3
C. 3 and 4
D. 1 and 4

3-11-2. Which molecule has the smallest bond angles?
A. CH₄
B. NH₃
C. H₂O

3-11-3. For the molecule represented by the Lewis structure below, the N-C-N bond angle is closest to...
A. 180^o
B. 109.5^o
C. 120^o

3-11-JJW. What is the geometry of NF₃?
A. trigonal planar
B. trigonal pyramidal
C. T-shaped

3-11-ALD. Which of the following molecules has a square planar molecular geometry?
A. methane
B. water
C. sulfur tetrafluoride
D. xenon tetrafluoride

1-25 Differentiate ionic and molecular compounds in terms of physical properties

2008-06-26T09:37:00.000-07:00

1-25-1. Which of the following is a solid with a very high melting point and conducts electricity when melted?
A. CaCl₂, B. CCl₄, C. H₂O

1-25-2.Which of the following is a strong electrolyte?
A. CH₃OH, B. KOH, C. HF, D. NH₃

1-25-3.Which of the following is a strong ectrolyte?
A. HCl, B. C₆H₁₂O₆, C. H₂S, D. NH₃

1-18 Differentiate and predict ionic and covalent bonding

2008-06-26T09:28:00.000-07:00

1-18-1. Which of the following pairs of atoms is most likely to form an ionic bond?
A. C and H, B. Ca and H, C. Hg and Hg

1-18-2. What type of bond is more likely between a carbon atom and an oxygen atom?
A. ionic, B. covalent, C. metallic

1-23 Classify compounds as molecular or ionic

2008-06-17T11:34:00.000-07:00

1-23-1. Which of the following is a molecular compound?
A. Na₂S, B. NH₃, C. (NH₄)₂SO₄, D. N₂

1-23-2. Which of the following is an ionic compound?
A. ethyl acetate, B. sulfuric acid,
C. sodium hydrogen carbonate, D. hydrazine

1-23-3. Which of the following is a molecular compound?
A. phosphorus trichloride, B. ammonium chloride
C. lithium aluminum hydride, D. sodium dihydrogen phosphate

1-22 Read/write formulas of polyatomic ions

2008-06-13T12:30:00.000-07:00

1-22-1. Which of the following polyatomic ions is not paired with its correct formula?
A. sulfate, SO₄^2-, B. carbonate, CO₄^2-,
C. phosphate, PO₄^3-, D. perchlorate, ClO₄^-

1-22-2. Which of the following polyatomic ions is not paired with its correct formula?
A. nitrate, NO₃^3-, B. borate, BO₃^3-,
C. carbonate, CO₃^2-, D. chlorate, ClO₃^-

1-22-3. Which of the following polyatomic ions is not paired with its correct formula?
A. permanganate, MnO₄^-, B. perchlorate, ClO₄^-,
C. persulfate, SO₄^-, D. perbromate, BrO₄^-

1-22-4. Which of the following polyatomic ions is not paired with its correct formula?
A. chlorite, ClO₂^-,B. hypochlorite, ClO^-,
C. phosphite, PO₂^-, D. sulfite, SO₃^2-

1-22-5. Which of the following polyatomic ions is not paired with its correct formula?
A. chromate, CrO₄^2-, B. dichromate, Cr₂O₈^2-,
C. molybdate, MoO₄^2-, D. permanganate, MnO₄^-

1-22-6. The formula of the bisulfite ion is...
A. S₂O₃^2-, B. S₂O₆^2- , C. HSO₃^-, D. S₂^2-

1-22-7. Which of the following is the correct formula for the mercury(I) ion?

A. Hg, B. Hg₂, C. Hg⁺, D. Hg₂²⁺

1-22-8. The formula of a thiosulfate ion is...
A. S₂O₃^2-, B. S₂O₆^2- , C. S₂O₄^2-, D. S₂O₈^2-

1-19 Describe and differentiate molecules and polyatomic ions

2008-06-12T12:36:00.000-07:00

1-19-1. What do molecules and polyatomic ions have in common?
A. They consist of at least two atoms sharing electrons
B. They consist of at least two atoms held together by ionic bonds
C. The number of protons is equal to the number of electrons

1-19-2. What type of bond holds the atoms together in the polyatomic ions chromate (CrO₄^2-) and nitrate (NO₃^-)?
A. ionic, ionic, B. ionic, covalent,
C. covalent, ionic, D. covalent, covalent

1-21 Classify polyatomic ions as oxoanions or non-oxoanions

2008-06-12T12:34:00.001-07:00

1-21-1. Which of the following is not an oxoanion?
A. chloride, B. hypochlorite, C. chlorite D. chlorate, E. perchlorate

1-20 Interpret formulas of molecules and polyatomic ions

2008-06-12T12:29:00.000-07:00

1-20-1. How many electrons are in a sulfur trioxide (SO₃) molecule and a sulfite ion (SO₃^2-)?
A. 40, 40,
B. 40, 42,
C. 38, 40,
D. 78, 80

1-20-2. How many hydrogen atoms are in 5 molecules of acetic acid (CH₃COOH)?
A. 3, B. 4, C. 15, D. 20

1-17 Predict stable monatomic ions formed from atoms

2008-06-12T12:24:00.000-07:00

1-17-1. Which of the following naturally-occurring ions is paired with its correct symbol?
A. potassium ion, K²⁺,
B. sulfide, S^3-,
C. barium ion, Ba²⁺,
D. iodide, I⁺

1-15 Classify ions as cations or anions

2008-06-12T12:20:00.000-07:00

1-15-1. Which of the following describes a cation?
A. an aluminum ion (Al³⁺),
B. an oxygen atom that has gained 2 electrons,
C. an ion with 17 protons and 18 electrons,
D. an ion with more neutrons than protons

1-15-2. Which of the following describes an anion?
A. a sodium ion (Na⁺),
B. a calcium atom that has lost 2 electrons,
C. an ion with 8 protons and 10 electrons

1-16 Interpret symbols and formulas of ions

2008-06-09T10:55:00.000-07:00

1-16-1. How many protons and electrons are in a magnesium ion (Mg²⁺)?
A. 10, 12, B. 12, 10, C. 24, 22, D. 22, 24

1-16-2. How many protons and electrons are in a nitride ion (N^3-)?
A. 7, 10, B. 7, 4, C. 10, 7, D. 4, 7

1-14 Describe how ions are formed from atoms

2008-06-06T12:14:00.000-07:00

1-14-1. A magnesium atom becomes a magnesium ion (Mg²⁺) by...
A. gaining two electrons, B. losing two electrons
C. gaining two protons, D. losing two protons

1-14-2. A nitrogen atom becomes a nitride ion (N^3-) by...
A. gaining 3 electrons, B. losing 3 electrons,
C. gaining 3 protons, D. losing 3 protons

1-13 Describe how the currently accepted model of the atom evolved from Dalton through Rutherford

2008-06-06T10:46:00.000-07:00

1-13-1. Which of these is true?
A. Dalton assumed that atoms are made up of electrons, protons, and neutrons
B. J.J. Thomson determined the charge and mass of electrons
C. In Rutherford's alpha scattering experiment, all of the alpha particles passed through the gold foil.
D. The alpha particles used in Rutherford's experiment are positively charged particles.

1-13-2. Assume circles and squares in the figures below represent atoms. According Dalton's atomic theory, which of the figures below best represents a sample of a compound?

1-13-3. Assume that circles and squares in the figure below represent atoms. According to Dalton's theory, which of the changes indicated is possible?

1-13-4. Consider the pictorial representation shown below for the molecular composition of a mixture. Using Dalton's atomic theory, the figure represents a mixture of...
A. an element and two compounds,
B. two elements and a compound,
C. three compounds

1-13-5. Match the pictorial representations showing four neighboring atoms to the scientist most closely associated with the atomic model.
A. 1-Dalton, 2-J.J.Thomson, 3-Rutherford
B. 1-J.J.Thomson, 2-Dalton, 3-Rutherford
C. 1-J.J.Thomson, 2-Rutherford, 3-Dalton
D. 1-Rutherford, 2-J.J.Thomson, 3-Dalton

1-13-6. Which of these scientists is most closely associated with the laboratory apparatus shown below?
A. John Dalton, B. J.J. Thomson, C. Ernest Rutherford, D. James Chadwick

1-13-7. Shown below is a diagram illustrating Rutherford's alpha scattering experiment. Alpha particles are represented by red circles. Which of the three labeled alpha particles (A, B, or C) will have the most typical trajectory?

1-11 Interpret symbols for isotopes

2008-06-06T10:31:00.000-07:00

1-11-1. The symbol ¹³C or C-13 represents an atom with...
A. 13 protons, B. 13 electrons, C. 13 neutrons, D. 13 nucleons

1-11-2. Which of the following has the largest mass number?
A. ⁵⁶Mn, B. ⁵⁶Fe, C. ⁵⁶Cr, D. they all have the same mass number

1-11-3. How many neutrons does an O-18 atom have?
A. 8, B. 10, C. 16, D. 18

1-10 Describe basic atomic structure (subatomic particles)

2008-06-05T11:41:00.000-07:00

1-10-1. Which of the following subatomic particles are found in the nucleus of an atom?
A. protons and neutrons, B. protons and electrons,
C. neutrons and electrons, D. protons, neutrons, and electrons

1-10-2. Which of the following has the largest total mass?
A. 2 protons + 4 electrons, B. 2 neutrons + 2 protons,
C. 6 electrons, D. they all have the same mass

1-10-3. Which of the following is false?
A. An atom's mass is concentrated in the nucleus
B. The atom's nucleus is positively charged
C. The number of electrons in an atom is equal to the number of protons
D. The number of protons in an atom is equal to the number of neutrons

1-9 Describe and apply the law of definite composition

2008-06-04T13:35:00.000-07:00

1-9-1. A 25.0 gram sample of a compound is found to be 24% chlorine by mass. What is the percentage of chlorine in a 50.0 g sample of the compound?
A. 24%, B. 48%, C. 12%, D. It depends where the sample came from

1-9-2. A 25.0 gram sample of a compound is found to be 24% chlorine by mass. How much chlorine is in a 50.0 g sample of the compound?
A. 24 g, B. 48 g, C. 12 g

1-9-3. A 17.0 g sample of a compound contains 14.0 g nitrogen and 3.0 g hydrogen. How much hydrogen does a 34.0 g sample of the compound contain?
A. 3.0 g, B. 6.0 g, C. 14.0 g, D. 28.0 g

1-9-4. A 32.0 g sample of a compound contains 16.0 g oxygen, 12.0 g carbon, and 4.0 g hydrogen. How much oxygen is present in a sample of this compound that contains 36.0 g carbon?
A. 12.0 g, B. 5.33 g, C. 48.0 g, D. 36.0 g

1-9-5. A 7.0 g sample of a compound contains 3.0 g of element "X" and 4.0 g of element "Y". What is the mass ratio of element "X" to element "Y" in a 70.0 g sample of this compound?
A. 0.75, B. 1.33, C. 7.5, D. 13.3

1-5 Write correct symbols for elements

2008-06-04T13:28:00.000-07:00

1-5-1. Which of the these elements is paired with its correct symbol?
A. magnesium, Mn,
B. potassium, Po,
C. fluorine, F,
D. argon, Ar

1-5-2. Which of the these symbols is paired with its correct name?
A. P, phosphate
B. Si, silver
C. Hg, hydrogen
D. Pb, lead

1-8 Describe the law of conservation of matter,(mass).

2008-06-04T13:19:00.000-07:00

1-8-1. A compound decomposes (breaks apart) into elements "X" and "Y". If the decomposition of 5.0 g of the compound produces
2.0 g of element "X", how much of element "Y" is also produced?

A. 2.0 g, B. 3.0 g, C. 5.0 g, D. impossible to tell

1-7 Describe naturally-occurring forms of elements

2008-06-04T13:14:00.000-07:00

1-7-1. Which of the following elements is the best electrical conductor?
A. carbon, B. germanium, C. manganese, D. iodine

1-7-2. Which of these naturally occurs as a monatomic gas under ordinary conditions?
A. helium, B. sodium, C. oxygen, D. nitrogen

1-7-3. Which of these elements naturally occurs as a diatomic gas under ordinary conditions?
A. bromine, B. iodine, C. mercury, D. chlorine

1-7-4. Which of these elements is not a gas under ordinary conditions?
A. bromine, B. helium, C. hydrogen, D. oxygen

1-6 Classify elements based on their location in the periodic table

2008-06-03T12:34:00.000-07:00

1-6-1. Which of the following is a metalloid?
A. Potassium, B. Silicon, C. Iron, D. Helium

1-6-2. Which of the following elements is a transition metal?
A. silicon, B. lead, C. sodium, D. chromium

1-6-3. Which of the following elements is a post-transition metal?
A. silicon, B. lead, C. sodium, D. chromium

1-6-4. Which of the following elements is a metal that belongs to a main group or representative group?
A. magnesium, B. zinc, C. sulfur, D. uranium

1-6-5. All of the following are true, except...
A. Sodium is an alkali metal, B. Neon is a noble gas,
C. Calcium is an alkaline earth metal, D. Oxygen is a halogen

3-2 Relate electronegativity and bond polarity

2008-06-03T12:16:00.000-07:00

3-2-1. Which pair of atoms would form a bond where the polarity is directed towards the first atom?
A. C and C, B. H and F, C. O and C, D. I and Cl

3-2-2. Which pair of atoms would form a polar covalent but essentially nonpolar bond?
A. N and N, B. H and C, C. Na and Cl, D. Be and I

3-2-ALD. Choose the diatomic molecule/ion that would have the least polar bond.
A. carbon monoxide
B. hydrofluoric acid
C. nitrogen
D. the cyanide ion

3-1 Relate electronegativity to location of atom in the periodic table

2008-06-03T12:12:00.000-07:00

3-1-1. Which of the following has the highest electronegativity?
A. Na, B. Br, C. F

3-1-2. Which type of element has the lowest electronegativity?
A. a metal, B. a nonmetal, C. a metalloid

3-1-JJW. Which element has the lowest electronegativity?
A. Ca, B. Se, C. S, D. Mg

3-1-ALD-1. Choose the diatomic molecule/ion that would have the least polar bond.
A.CO, B. HF, C. N₂, D. CN^-

3-1-ALD-2. Of the elements fluorine, carbon, oxygen, and chlorine, which is the most electronegative?
A. F, B. Cl, C. C, D. O

2-1 Describe electromagnetic radiation in terms of waves and photons

2008-05-30T11:58:00.000-07:00

2-1-1. Illustrated below is a snapshot of the electric field component of an electromagnetic wave as it travels through space. At which of the locations indicated would a charged particle experience the strongest force?

2-1-2. Which of the following wavelengths is associated with the electromagnetic radiation that humans can see?
A. 500 nm, B. 300 nm, C. 0.0005 cm

2-1-3. Which of the following regions of the electromagnetic spectrum has the longest wavelengths?
A. x-rays, B. visible, C. microwave, D. radiowave

2-1-4. What is the frequency of the electromagnetic wave with a wavelength of 250 nm?
A. 1.2x10⁶ Hz, B. 1.2x10¹⁵ Hz, C. 6.0x10¹⁴ Hz

2-1-5. What is the energy of a photon of ultraviolet radiation with a wavelength of 250 nm?
A. 5.0 eV, B. 2.5 eV, C. 4.0x10^-2 eV

2-1-6. Which of the following regions of the electromagnetic spectrum has the most energetic photons?
A. x-rays, B. visible, C. microwave, D. radiowave

2-1-7. Which of the following characteristics of electromagnetic radiation is not associated with what we perceive as color?
A. wavelength, B. frequency, C. wave speed, D. photon energy

3-3 Write and interpret Lewis dot symbols

2008-05-30T11:50:00.000-07:00

3-3-1. How many electrons are shown in the Lewis symbol for a nitrogen atom?
A. 5, B. 7, C. 8, D. 14

3-3-2. How many dots are shown in the Lewis symbol for a nitride ion?
A. 5, B. 7, C. 8, D. 14

3-3-ALD. Choose the correct Lewis Dot symbol for the oxide ion, O^2-.
A. O with 8 dots
B. O with 4 dots
C. O with 2 dots
D. O with 6 dots

3-5 Draw Lewis structures

2008-05-30T09:44:00.000-07:00

3-5-1. Which of the following has a double bond?
A. HCl, B. O₂^2-, C. N₂, D. PF

3-5-2. Which of the structures shown is valid for HOCl?

3-5-3.Which of the following acquires an octet by bonding with three hydrogen atoms?
A. Cl, B.O, C. C, D. N

3-5-4.Consider the following partially-drawn structure of 2-butene (C₄H₈) where only the C atoms are shown: C-C=C-C.
When this structure is completed following the octet/duet rule, how many hydrogen atoms are bonded to the first carbon?
A. 1, B. 2, C. 3, D. 4

3-5-JJW. Which is the correct Lewis structure of nitrite ion, NO₂^-?

3-5-ALD. Choose the correct Lewis structure for germanium disulfide, GeS₂.

2-7 Relate electron configuration and properties of ions to the parent atoms' location in the periodic table

2008-05-30T09:43:00.000-07:00

2-7-1. What is the electron configuration of naturally occurring aluminum ion?
A. [Ne] 3s² 3p¹
B. [Ne] 3s²
C. [Ne] 3s¹
D. [Ne]

2-7-2. All of the following have the same electron configuration except...?
A. Ne, B. Na⁺, C. O^-, D. O^2-

2-7-3. What is the electron configuration of Fe³⁺?
A. [Ar] 4s² 3d⁶
B. [Ar] 4s² 3d³
C. [Ar] 4s¹ 3d⁴
D. [Ar] 3d⁵

2-7-4. Which of the following has the largest size?
A. K, B. K⁺, C. Se, D. Li

2-7-5. Which of the following has the largest size?
A. Cl, B. Cl^-, C. F, D. F^-

2-7-6. Which of the following has the highest ionization energy?
A. Ne, B. Mg²⁺, C. Mg, D. F^-

2-7-ALD. What is the charge on the most stable ion of the element Sr?
A. +1, B. +2, C. 0, D. -6

3-8 Use formal charges and electronegativity to assess feasibility of a structure or extent of contribution to a resonance hybrid

2008-05-30T09:36:00.000-07:00

3-8-1. Based on formal charges, which of the Lewis structures shown below is the most likely structure of CH₄O?
A. Structure I, B. Structure II, C. Structure III

3-8-2. Based on formal charges, which of the Lewis structures shown below is the most likely structure of HNO₂?
A. Structure I, B. Structure II, C. Structure III

2-6 Relate properties (size, ionization energy) of an atom to its location in the periodic table

2008-05-30T09:24:00.000-07:00

2-6-1. Which of the following has the highest ionization energy in the period where it belongs?
A. Ne
B. Na
C. Br
D. Mn

2-6-2. Which of the following has the highest ionization energy?
A. Na, B. Rb, C. N

2-6-3. The ionization energy of bromine atoms is the energy associated with which of the following?
A. Br(g) → Br⁺(g) + e^-
B. Br₂(l) → 2 Br⁺(g) + 2e^-
C. Br(g) + e^- → Br^-(g)
D. Br₂(l) + 2e^- → 2 Br^-(aq)

2-6-4. Which of the following has the smallest atomic radius?
A. O
B. S
C. Li

2-6-5. The increasing trend in ionization energy across a period, from left to right, is due to...
A. Increasing repulsions among electrons in the valence shell
B. Increasing effective nuclear charge
C. Increasing number of core electrons
D. Increasing size of the valence shell

2-6-6. The decreasing trend in ionization energy going down a group is, is due to...
A. Increasing repulsions among electrons in the valence shell
B. Increasing effective nuclear charge
C. Decreasing number of core electrons
D. Increasing size of valence shell

2-6-7. Which atom's first five ionization energies best resembles the pattern shown in the graph?
A. Na
B. Mg
C. Al
D. K

2-6-ALD. Rank the following three elements in order of increasing atomic radius: Cs, At, N
A. Cs, At, N
B. N, At, Cs
C. At, Cs, N
D. Cs, N, At

2-6-JJW. Which of the following species has the largest radius?
A. Na
B. K
C. Kr

2-5 Relate (ground-state) electron configuration of an atom to its location in the periodic table

2008-05-30T09:16:00.000-07:00

2-5-1. Which of the following does not have a valence shell of n=4?
A. Ga, B. Al, C. K, D. Mn

2-5-2. What is the principal quantum number of the valence electrons of iodine?
A. 0, B. 4, C. 5, D. 43

2-5-3. Which of the following has no electron in its valence p subshell?
A. Ga, B. Al, C. B, D. Mn

2-5-4. For which of these are all the occupied d subshells completely filled?
A. Sc, B. Zr, C. Mn, D. Cd

2-5-5. Which of the following has a valence configuration of ns¹?
A. Na, B. Be, C. Mg, D. Ca

2-5-ALD. When written in noble gas configuration, where [X] represents all electrons possessed by the noble gas in the row above the element in question and n corresponds to the principal quantum number or row number in the periodic table, which of the following corresponds to the ground state electron configuration of the valence electrons for elements in the same group as O in the periodic table?
A. [X]ns² np⁴
B. [X]ns¹ np⁵
C. [X]ns³ np³
D. [X]ns⁰ np⁶

2-5-JJW. What is the ground state electron configuration for zirconium?
A. [Kr]5s²5p², B.[Kr]5s²5d², C. [Kr]5s²4d²

4-7 Determine empirical and molecular formulas

2008-05-30T09:14:00.000-07:00

4-7-1. What is the sum of the subscripts in the empirical formula of C₆H₁₂?
A. 1, B. 2, C. 3, D. 18

4-7-2. A compound with an empirical formula of NO₂ has a molar mass between 43 and 47 g/mol. What is the molecular formula of the compound?
A. NO₂, B. N₂O, C. N₂O₃, D. N₂O₄

4-7-3. A sample of a compound contains 3.581x10²² C atoms and 1.436x10²³ H atoms. What is the empirical formula of the compound?
A. CH, B. CH₄, C. C₂H₅, D. C₃H₄

4-7-4. A sample of a compound contains 0.5860 moles of P and 1.466 moles of O. What is the empirical formula of the compound?
A. PO, B. PO₄, C. P₂O₅, D. P₃O₄

4-7-5. A sample of a compound contains 19.27 g Fe and 7.360 g O. What is the empirical formula of the compound?
A. FeO, B. FeO₂, C. Fe₂O₃, D. Fe₃O₄

4-7-6. Which of the following is an empirical formula of a compound that is 14.37% hydrogen by mass?
A. CH2
B. CH3
C. C2H4
D. C3H6

4-7-JJW-1. What is the formula for the compound composed of 71.62% gold, 13.10% carbon, and 15.28% nitrogen?
A. AuCN B. Au(CN)₂ C. Au(CN)₃ D. Au(CN)₄

7-2 Assign oxidation numbers

2008-05-30T09:03:00.000-07:00

7-2-1. Which of the following has the largest oxidation number for chlorine?
A. MgCl₂, B. CCl₄, C. Cl₂, D. ClO₂^-

7-2-2. For which of the following is the oxidation number of F equal to zero?
A. CaF₂, B. CF₄, C. NaF, D. F₂

7-2-CML. What is the oxidation number of the metal in CuCl?
A. -1, B. 0, C. +1, D. +2

7-2-JJW. What is the oxidation number of sulfur in strontium sulfate, SrSO₄?
A. -2, B. 0, C. 2, D. 4, E. 6

2-4 Write or identify ground state and excited state electron configurations

2008-05-30T08:59:00.000-07:00

2-4-1. Which of the following is not a valid electron configuration for a lithium atom, which has 3 electrons?
A. 1s³, B.1s², 2s¹, C. 1s², 2p¹, D. 1s¹ 2p¹ 3s¹

2-4-2. In a typical atom, which of these orbitals is filled last?
A. 3p, B. 3d, C. 4s, D. 4p

2-4-3. Which of the following is the ground state electron configuration of Sulfur?
A. 1s² 2s² 2p⁶ 2d⁶
B. 1s² 2s² 2p⁶ 3s² 3p⁴
C. 1s² 2s² 2p⁷ 3s¹ 3p³
D. 1s² 2s² 2p⁶ 3s² 3p⁶

2-4-4. Which of the following is the ground state electron configuration of Al?
A. [Ne] 3s² 3p¹
B. [He] 2s² 2p⁶ 3s² 3p¹
C. [Mg] 3p¹
D. all of the above

2-4-5. How many electrons are unpaired in the ground state of Oxygen?
A. 0, B. 1, C. 2, D. 3

2-4-6. Which of the following atoms is not paramagnetic?
A. Na, B. Mg, C. C, D. Ti

2-4-JJW-1. What is the ground state electron configuration of Se^2-?
A. [Ar]4s²4p⁴
B. [Ar]4s²4p⁶
C. [Ar]4s²3d¹⁰4p⁴
D. [Ar]4s²3d¹⁰4p⁶

2-4-JJW-2. What is the ground state electron configuration for zirconium?
A. [Kr]5s²5p²
B. [Kr]5s²5d²
C. [Kr]5s²4d²

2-4-ALD. Choose the electron configuration that corresponds to an excited state for the K atom.
A. 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹
B. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
C. 1s² 2s² 2p⁶ 3s² 3p⁶
D. None of the above

2-4-CML. Which is the excited electron configuration for strontium?
A. [Kr]5s²
B. [Kr]5s¹
C. [Kr]5s²5p¹
D. [Kr]5s¹5p¹

7-4 Identify atoms oxidized or reduced based on oxidation numbers

2008-05-30T08:49:00.000-07:00

7-4-1. What is reduced in the following reaction?
Cu(s) + HNO3(aq) = NO(g) + Cu(NO3)2(aq) + H2O(l)
A. Cu, B. H, C. N, D. O

7-4-2. In the reaction: 2 BaO₂(s) = 2 BaO(s) + O₂(g)
Which is false?
A. BaO₂ is oxidized, B. BaO₂ is reduced
C. Ba is oxidized, D. O is oxidized
E. O is reduced

7-4-JJW. In the reaction, 2 Fe₂O₃ + 3 C → 4 Fe + 3 CO₂ which element is oxidized?
A. Fe, B. O, C. C

7-4-ALD. Identify the element that is oxidized in the chemical reaction given below:
Mn(s) + Fe(NO₃)₃(aq) → Mn(NO₃)₂(aq) + Fe(s)

A. Mn, B. Fe, C. N, D. O

2-2 Describe the Bohr model and relate to atomic spectra

2008-05-30T07:15:00.000-07:00

2-2-1. Which of the following is true regarding the Bohr model?
A. it assumes that electrons move around the nucleus in elliptical orbits
B. it only works for atoms or ions with only one electron
C. it assumes that electrons will eventually crash into the nucleus
D. it predicts that light is produced when an electron transfers from a smaller orbit to a larger orbit

2-2-2. For Bohr's model, if "a" is the radius of the first allowed orbit of hydrogen, what is the radius of the third allowed orbit?
A. 3a, B. 6a, C. 8a, D. 9a

2-2-3. For Bohr's model, the energy of an electron in any of the orbits is a negative value. This means that...
A. the electron is moving in a clockwise direction
B. the electron is moving counterclockwise
C. the electron has imaginary speed
D. none of these

2-2-4. According to Bohr's model, what is the energy of the photon released when an electron jumps from the third orbit to the second orbit of the hydrogen atom?
A. 13.6 eV, B. 1.89 eV, C. 10.2 eV, D. 2.27 eV

2-2-5. According to Bohr's model, which of the following wavelengths will not be absorbed by an electron in the first orbit?
A. 142 nm, B. 122 nm, C. 97.5 nm, D. 94.0 nm

2-3 Describe orbitals and rules for assigning electrons to orbitals

2008-05-14T06:56:00.000-07:00

2-3-1. Atomic orbitals are mathematical functions that allow us to determine all of the following except...
A. the location and velocity of an electron at any given time,
B. the probability of finding an electron in any given region,
C. how an atom would behave in a magnetic field,
D. the energy needed to remove an electron from an atom

2-3-2. Which of the following are allowed values of the quantum numbers n and l, respectively ?
A. 1.5 and 0, B. 3 and 3, C. 2 and 1, D. 0 and 1

2-3-3. What is the value of the orbital quantum number for an electron in a 3p orbital?
A. 0, B. 1, C. 2, D. 3

2-3-4. Which of the following is not a valid name for an atomic orbital?
A. 1s, B. 2s, C. 2d, D. 3p

2-3-5. Which of the following is not an allowed value of the magnetic quantum number (ml) for an electron in a 3d orbital?
A. 3, B. 2, C. 0, D. -1

2-3-6. How many ways can the magnetism generated by the orbital motion of an electron in a 3p orbital be oriented?
A. 1, B. 3, C. 5, D. 7

2-3-7. How many ways can the intrinsic magnetism of an electron in a 4d orbital be oriented?
A. 2, B. 3, C. 5, D. 10

2-3-8. What is the maximum number of electrons that can be assigned to a 2p orbital of an atom?
A. 2, B. 3, C. 6, D. 10

2-3-9. How many sets of quantum numbers can an electron in a 4p subshell have?
A. 2, B. 3, C. 6, D. 10

2-3-10. Which of the following can accommodate the most number of electrons?
A. a 4f orbital, B. the 3d subshell, C. the n=2 shell, D. a 3d orbital

1A-4 Properly round off results of calculation involving measurements

2008-04-16T18:13:00.001-07:00

1A-4-1. How should the result of the following calculation be reported:
80.00 g / 10.0 mL ?
A. 8 g/mL, B. 8.0 g/mL, C. 8.00 g/mL, D. 8.000 g/mL

1A-4-2. How should the result of the following calculation be reported:
0.800 m / 0.010 s?
A. 80 m/s, B. 80.0 m/s, C. 8.0x10¹ m/s, D. 8x10¹ m/s

1A-4-3. To how many significant figures should the result of the following calculation be reported:
2500.0 + 25 g ?
A. 2, B. 3, C. 4, D. 5

1A-4-4. To how many significant figures should the result of the following calculation be reported:
2500 mL + 25 mL?
A. 2, B. 3, C. 4, D. 5

1A-4-5. How should the result of the following calculation be reported:
0.0072 + (0.0050)(39.0)?
A. 0.20, B. 0.21, C. 0.202, D. 0.2022

1A-4-6. How should the result of the following calculation be reported, assuming that 1.8 and 32 are exact numbers:
32 + (1.8)(2.37)?
A. 36, B. 36.3, C. 36.27, D. 36.266

1A-4-7 The volume of a sphere of radius r is given by the formula:
V = (4/3)(π)(r³), The radius of a sphere is measured to be 5.00 cm. What is the proper way to report the volume?
Note: π = 3.141592653589793238462643383279...
A. 520 cm³, B. 523 cm³, C. 524 cm³