AP CHEMISTRY
Week 7 Problem Set
Solutions
, AP Chemistry Week 7
Problem Set Solution
Multiple Choice Questions
Question 1: Given the equilibrium constant for reaction 1. Determine the equilibrium
constant for reaction 2.
Reaction 1: Ge(g) + 2Cl2(g) ⇄ GeCl4(g) Keq=1 × 1010
Reaction 2: 2GeCl4(g) ⇄ 2 Ge(g) + 4 Cl2(g) Keq= ?
A) 1 × 10-20
B) 1 × 10-10
C) 1 × 1010
D) 1 × 1020
Answer: A
The second reaction is the reverse of the first reaction, and multiplied by 2.
Whenever a reaction is reversed, we take the inverse. If it’s multiplied by a factor
“n,” we raise to power of n.
1 1
𝐾𝑒𝑞2 = 2
= 10 2
= 1 × 10−20
(𝐾𝑒𝑞1) (1 × 10 )
Question 2: The value of Kw at 40°C is 3.0 x 10-14. What is the pH of pure water at 40℃?
A) 3.0
B) 6.8
C) 7.0
D) 7.2
Answer: B
Recall 𝑝𝐾𝑤 = 𝑝𝐻 + 𝑝𝑂𝐻 and in pure solutions such as water, the pH=pOH.
𝑝𝐾𝑤 = 𝑝𝐻 + 𝑝𝑂𝐻
𝑝𝐾𝑤 = 𝑝𝐻 + 𝑝𝐻
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Week 7 Problem Set
Solutions
, AP Chemistry Week 7
Problem Set Solution
Multiple Choice Questions
Question 1: Given the equilibrium constant for reaction 1. Determine the equilibrium
constant for reaction 2.
Reaction 1: Ge(g) + 2Cl2(g) ⇄ GeCl4(g) Keq=1 × 1010
Reaction 2: 2GeCl4(g) ⇄ 2 Ge(g) + 4 Cl2(g) Keq= ?
A) 1 × 10-20
B) 1 × 10-10
C) 1 × 1010
D) 1 × 1020
Answer: A
The second reaction is the reverse of the first reaction, and multiplied by 2.
Whenever a reaction is reversed, we take the inverse. If it’s multiplied by a factor
“n,” we raise to power of n.
1 1
𝐾𝑒𝑞2 = 2
= 10 2
= 1 × 10−20
(𝐾𝑒𝑞1) (1 × 10 )
Question 2: The value of Kw at 40°C is 3.0 x 10-14. What is the pH of pure water at 40℃?
A) 3.0
B) 6.8
C) 7.0
D) 7.2
Answer: B
Recall 𝑝𝐾𝑤 = 𝑝𝐻 + 𝑝𝑂𝐻 and in pure solutions such as water, the pH=pOH.
𝑝𝐾𝑤 = 𝑝𝐻 + 𝑝𝑂𝐻
𝑝𝐾𝑤 = 𝑝𝐻 + 𝑝𝐻
02
