Homework #2-solutions - clow(twc432 Homework#2...

clow (twc432) – Homework #2 – holcombe – (51160) 1
This print-out should have 22 questions.
Multiple-choice questions may continue on
the next column or page – find all choices
before answering.
001 10.0points
Consider two closed containers. Container
X is a 2 L container that contains 0.5 L of
acetone. Container Y is a 2 L container that
contains 1.8 L of acetone. Both containers and
contents are at 30
◦
C. Which of the following
is true?
1. The vapor pressures in both containers
are equal. correct
2. The vapor pressure in container Y is
greater.
1. 260 torr
2. 274 torr correct
3. 33.0 torr
4. 241 torr
3. You would need information about the
shape of the containers to be able to answer
this question.
4. The vapor pressure in container X is
greater.
Explanation:
002 10.0points
Which of the following is a restatement of
Henry’s Law?
1. Adding a non-volatile solute to a liquid
will lower its vapor pressure.
2. As the partial pressure of a gas above a
liquid increases, the gas’s solubility in that
liquid also increases. correct
3. Heating a solution will decrease the solu-
bility of gases dissolved in it.
4. A mixture of two liquids will have a vapor
pressure that isn’t equal to either of the pure
liquid’s vapor pressures.
Explanation:
Henry’s law, formulated by William Henry
is 1803 states: ”At a constant temperature,
the amount of a given gas dissolved in a given
type and volume of liquid is directly propor-
tional to the partial pressure of that gas in
equilibrium with that liquid.”
003 10.0points
The vapor pressures of pure carbon disulfide
and carbon tetrachloride are 360 and 99.8
torr, respectively, at 296 K. What is the vapor
pressure of a solution containing 50.0 g of each
compound?
Explanation:
004 10.0points
For gases that do not react chemically with
water, the solubility of the gas in water gen-
erally (decreases, increases) with an increase
in the pressure of the gas and (decreases, in-
creases) with increasing temperature.
4. decreases; increases
Explanation:
An increase in pressure means that you
have increased the concentration of gas above
the solvent surface, thereby increasing the
concentration of the gas in the solvent. In-
creasing the temperature will decrease the
solubility of the gas.
005 10.0points
The vapor pressure of pure CH
2
Cl
2
(molecu-
lar weight = 85 g/mol) is 133 torr at 0
◦
C and
the vapor pressure of pure CH
2
Br
2
(molecu-

clow (twc432) – Homework #2 – holcombe – (51160)