Ch. 17 & 20 equilibrium & electrochemistry test [90 point] AP Chemistry

 

Show your work in an organized manner, include any relevant equation / formula, proper units in your work / answer, and the proper number of significant figures in your answer.

 

Academic Honesty: The answers on this test are my own and I am using only the allowed set of notes as described in the syllabus. I have not discussed the test questions with anyone before or during the test nor have I seen the test questions prior to the exam. If you violate any of the preceding items or do not sign, your semester grade is a F.

 

Signature: ___________________

 

1. Calculate the pH of a solution containing: [20 points]

a. 50.0 mL of a 10.0 mM HCl and 15.0 of a 60.0 mM KOH

b. 50.0 mL of a 10.0 mM acetic acid and 5.0 mL of a 60.0 mM NaOH

2. Sketch the titration curve involving 50.0 mL of a 10.0 mM HCl titrated by 60.0 mM KOH; label the pH and volume of KOH (V KOH) axis [15 points]

a. V KOH = 0

b. V KOH = V KOH, at the end point

c. V KOH = ∞

 

3. What is the solubility of lead (II) chloride in: [15 points]

a. water

b. 0.1 mM NaCl

c. rationalize the difference in solubility in part a versus part b

4. Sketch a Voltaic cell using zinc and silver electrodes in a solution of zinc cations and silver cations, respectively. [20 points]

a. at the proper electrode, label / identify

the half-reaction

is it an oxidation or reduction half-reaction

does the half-reaction, consume or generate electrons

is it the cathode or anode

direction of current and electrons in the circuit

b. write the balanced net ionic equation of the above reaction that would be spontaneous; justify that the reaction is spontaneous.

5. In an electrolytic cell using carbon and zinc electrodes in a solution of 888 mM zinc nitrate, the current in the system is 10.0 mA. What is the amount of time needed to plate 1125 mg zinc on the carbon electrode ? [10 points]

 

Old topic [10 points]

Determine the amount of heat in the combustion of 10.0 g of ethane.