Questions 1-3 Refer to the Following Molecules

Name ………………………………………… AP Chemistry

Review Quiz April 14, 2011

Note: For all questions, assume that the temperature is 298 K, the pressure is 1.00 atmosphere, and solutions are aqueous unless otherwise specified. Part A Directions: Each set of lettered choices below refers to the numbered statements immediately following it. Select the one lettered choice that best fits each statement and then fill in the corresponding oval on the answer sheet. A choice may be used once, more than once, or not at all in each set.

Questions 1-3 refer to the following molecules. Questions 4–5 refer to the following solid compounds.

(A) CO2 (A) PbSO4

(B) H2O (B) CuO

(C) CH4 (C) KMnO4

(D) C2H4 (D) KCl

(E) PH3 (E) FeCl3

1. ___ The molecule with only one double bond D 4. ___ Is purple in aqueous solution C

2. ___ The molecule with the largest dipole moment B 5. ___ Is white and very soluble in water D

3. ___ The molecule that has trigonal pyramidal geometry E

Questions 6–9 refer to the reactions represented below.

– + (A) H2SeO4 (aq) + 2 Cl (aq) + 2 H (aq)  H2SeO3 (aq) + Cl2 (g) + H2O(1)

(B) S8 (s) + 8 O2 (g)  8 SO2 (g) – – – (C) 3 Br2 (aq) + 6 OH (aq)  5 Br (aq) + BrO3 (aq) + 3 H2O(l) 2+ 2– (D) Ca (aq) + SO4 (aq)  CaSO4 (s) – 2– (E) PtCl4 (s) + 2 Cl (aq)  [PtCl6] (aq)

6. ___ A precipitation reaction D

7. ___ A Lewis acid-base reaction that produces a coordination complex E

8. ___ A reaction in which the same reactant undergoes both oxidation and reduction C

9. ___ A combustion reaction B Part B Directions: Each of the questions or incomplete statements below is followed by five suggested answers or completions. Select the one that is best in each case.

10. A flask contains 0.25 mole of SO2 (g), 0.50 mole of (B) 600 mm Hg CH4 (g), and 0.50 mole of O2 (g). The total pressure (C) 250 mm Hg of the gases in the flask is 800 mm Hg. What is the (D) 200 mm Hg partial pressure of the SO2 (g) in the flask? (E) 160 mm Hg (A) 800 mm Hg 11. Which of the following gases has the greatest rate of effusion through a pinhole? (C) O2 (D) Ne (A) CO (E) NO (B) Xe

3 C2H2 (g)  C6H6(g) 15. Which of the following describes the changes in 12. What is the standard enthalpy change, H , for the ∆ ˚ forces of attraction that occur as H O changes phase reaction represented above? ( H of C H (g) is 2 ∆ ˚ f 2 2 from a liquid to a vapor? -1 -1 230 kJ mol ; ∆H˚f of C6H6 (g) is 83 kJ mol .) (A) H—O bonds break as H—H and O—O bonds (A) –607 kJ form.

(B) –147 kJ (B) Hydrogen bonds between H2O molecules are (C) –19 kJ broken.

(D) +19 kJ (C) Covalent bonds between H2O molecules are (E) +773 kJ broken. (D) Ionic bonds between H+ ions and OH– ions are broken. 13. At 25˚ C, aqueous solutions with a pH of 8 have a + hydroxide ion concentration, [OH–], of (E) Covalent bonds between H ions and H2O molecules become more effective. (A) 110–14 M (B) l 10–8 M 16. Which of the following properties generally de- (C) l 10–6 M creases across the periodic table from sodium to (D) 1 M chlorine? (E) 8 M (A) First ionization energy (B) Atomic mass 14. In a saturated solution of Zn(OH) at 25 C the value (C) Electronegativity 2 ˚ (D) Maximum value of oxidation number of [OH-] is 2.010–6 M. What is the value of the (E) Atomic radius solubility-product constant, Ksp, for Zn(OH)2 at 25˚ C? 17. By mixing together 0.35 M NaOH and 0.40 M (A) 4.010 –18 NaOH, it is possible to create all of the following (B) 8.010 –18 solutions EXCEPT (C) 1.610 –17 (A) 0.40 M NaOH (B) 0.39 M NaOH (C) 0.38 M NaOH (D) 0.37 M NaOH (D) 4.010 –12 (E) 0.36 M NaOH (E) 2.010 –6

Directions: For each of the following three reactions, in part (i) write a balanced equation for the reaction and in part (ii) answer the question about the reaction. In part (i), coefficients should be in terms of lowest whole numbers. Assume that solutions are aqueous unless otherwise indicated. Represent substances in solution as ions if the substances are extensively ionized. Omit formulas for any ions or molecules that are unchanged by the reaction.

(a) Solid magnesium carbonate decomposes as it is heated.

(i) Write the balanced equation for the reaction above. MgCO3  MgO + CO2 (ii) Predict the algebraic sign of ∆S˚ for the reaction. Explain your reasoning. ∆S˚ is positive; solid  gas and more products than reactants (b) Solid calcium oxide is exposed to a stream of sulfur trioxide gas.

(i) Write the balanced equation for the reaction above. CaO + SO3  CaSO4 (ii) What type of reaction has occurred? synthesis

(c) A sample of carbonic acid is heated. (i) Write the balanced equation for the reaction above. H2CO3  H2O + CO2 (ii) Identify the type of reaction that has occurred. decomposition