Version 181 – Quiz 2 – laude – (51155) 1
This print-out should have 8 questions.
Multiple-choice questions may continue on
the next column or page – find all choices
before answering.
001 5.0 points
The ionization constant Kwof water at 60◦C
is 1.0×10−13. What is the pH of pure water
at this temperature?
1. 6.5 correct
2. 5.5
3. 7.5
4. 13.0
5. 7.0
Explanation:
Kw= 1.0×10−13
2 H2O⇀
↽H3O−+ OH−
Kw= [H3O+][OH−] = 1.0×10−13
In pure water
[H3O+] = [OH−] = p1×10−13 M
= 3.16228 ×10−7M
pH = −log 3.16228 ×10−7= 6.5
002 5.0 points
Consider the reaction
2 HgO(s) ⇀
↽2 Hg(ℓ) + O2(g) .
What is the form of the equilibrium constant
Kcfor the reaction?
1. None of the other answers is correct.
2. Kc=[O2]
[HgO]2
3. Kc= [Hg]2[O2]
4. Kc=[Hg]2[O2]
[HgO]2
5. Kc= [O2]correct
Explanation:
Solids and liquids are not included in the K
expression.
003 5.0 points
For the endothermic reaction
H2(g) + I2(g) ⇀
↽2 HI(g)
which of
I) increasing the pressure;
II) decreasing the volume;
III) increasing the temperature
will shift the equilibrium toward the prod-
ucts?
1. I only
2. II only
3. III only correct
4. I, II and III
5. I and III only
6. I and II only
Explanation:
Since the number of moles of gas are equal
on both sides of the equation, then volume
and pressure will have no affect on the equi-
librium. Since the reaction is endothermic,
lowering the temperature will favor the prod-
ucts.
004 5.0 points
If ∆G◦= 27.1 kJ at 25◦C for the reaction
CH3COOH(aq) + H2O(ℓ)→
CH3COO−(aq) + H3O+(aq) ,
calculate Kafor this reaction at 298 K.
1. 5.63 ×104
2. 1.15 ×10−11
3. 1.01
4. 9.89 ×10−1
