_____1. . C2H4(G) Is Reduced by H2(G) in the Presence of a Solid Platinum Catalyst, As

AP Chemistry Name : Worksheet : Ch. 15 : Obj 1-9(CG) Date :

A. Review : platinum C2H4(g) + H2(g) <======> C2H6(g) _____1. . C2H4(g) is reduced by H2(g) in the presence of a solid platinum catalyst, as represented by The equation above. Factors that could affect the rate of the reaction include which of the following? I. Changes in the partial pressure of H2(g) II. Changes in the particle size of the platinum catalyst III. Changes in the temperature of the reaction system

(A) III only (C) I and III only (E) I, II, and III (B) I and II only (D) II and III only

2 NH3(g) → 3 H2(g) + N2(g) ∆H298º = 92 kJ/molrxn

_____2. According to the information above, what is the standard enthalpy of formation, ∆Hºf , for NH3(g) at 298 K ? (A) −92 kJ/mol (C) 46 kJ/mol (E) 184 kJ/mol (B) −46 kJ/mol (D) 92 kJ/mol

_____3. The percentage of silver in a solid sample is determined gravimetrically by converting the silver to Ag+(aq) and precipitating it as silver chloride. Failure to do which of the following could cause errors in the analysis? I. Account for the mass of the weighing paper when determining the mass of the sample II. Measure the temperature during the precipitation reaction III. Wash the precipitate IV. Heat the AgCl precipitate to constant mass

(A) I only (C) I and IV (E) I, III, and IV (B) I and II (D) II and III

_____4. Which of the following lists the substances F2, HCl, and HF in order of increasing boiling point?

(A) HF < HCl < F2 (C) HCl < F2 < HF (E) F2 < HF < HCl (B) HF < F2 < HCl (D) HCl < HF < F2

______5. A solution containing which one of the following pairs of substances will form a buffer solution? a. NaI, HCl b. KCl, HCl

c. RbNO3, HNO3 d. NaC2H3O2, HC2H3O2 e. NaOH and HNO3 ______6. A solution containing which one of the following pairs of substances will form a buffer solution? a. 50.0 mL of 1.0 M NaOH and 50.0 mL of 1.0 M HCl

b. 50.0 mL of 1.0 M NH3 and 20.0 mL of 1.0 M HCl c. 50.0 mL of 1.0 M KCN and 50.0 mL of 1.0 M HCl d. 50.0 mL of NaOH and 20.0 mL of HCl e. two of the above _____7. What change will be caused by addition of a small amount of HCl to a solution containing nitrite ions and nitrous acid? a. The concentration of hydronium ions will increase significantly. b. The concentration of nitrite ions will increase as will the concentration of hydronium ions. c. The concentration of nitrous acid will decrease and the concentration of nitrite ions will increase. d. The concentration of nitrite ions will decrease and the concentration of nitrous acid will increase. e. The nitrite ions will precipitate out of solution as its acid salt.

____ 8. Which of the following could be added to a solution of sodium cyanide to produce a buffer?

hydrocyanic acid hydrobromic acid potassium cyanide sodium bromide

a) hydrocyanic acid only b) hydrocyanic acid or hydrobromic acid c) hydrobromic acid only d) potassium cyanide only e) sodium bromide or potassium cyanide 9. Write reactions to show how a solution containing hydrocyanic acid and sodium cyanide acts as a buffer when a strong acid or base is added.

10. Calculate the pH of each of the following solutions. -10 a. 0.10 M phenolic acid (HOC6H5, Ka = 1.6 x 10 )

b. 0.10 M sodium phenolate (NaOC6H5)

c. A mixture containing 0.10 M HOC6H5and 0.10 M NaOC6H5

d. Calculate the pH after 0.020 mol of NaOH is added to 1.00 L of the solution in 6c.

–8 11. Calculate the pH of a buffered solution made from 0.20 M hypochlorous acid(Ka = 3.5 x 10 ) and 0.15 M sodium hypochlorite.

12. A buffered solution is made by adding 35.0 g sodium porpanoate (NaC3H5O2) to 500.0 mL of a 0.64 M -5 solution of propanoic acid (HC3H5O2, Ka = 1.3 x 10 ). What is the pH of the final solution? (Assume no volume change.)

Answers : 10a. 5.40 10b. 11.40 10c. 9.79 10d. 9.97 11. 7.33 12. 4.94