Answers25-26 KCS18 Chemistry ICTest

Colligative Properties Answers

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A student lives in a place that receives lots of snow and ice during the winter. The student has observed that the highway department spreads salt on the road after a snowfall. Which of the following correctly explains why the highway department uses salt on the roads?

S
Salt lowers the freezing point of water, which makes the melted snow on the road less likely to form ice.
S
Salt raises the freezing point of water, which makes the melted snow on the road less likely to form ice.
S
Salt raises the vapor pressure of water, which makes the melted snow more likely to evaporate before it freezes.
S
Salt lowers the osmotic pressure of water, which makes the melted snow more likely to be absorbed into the ground before it freezes.
2
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A student placed equal volumes of honey and of water in two, identical, open dishes, and left them at room temperature for 8 hours. She observed that the amount of water decreased, but the amount of honey seemed unchanged. Knowing that honey is a highly concentrated solution of sugar in water, which statement should the student make to explain this phenomenon?

H
Honey has a much lower vapor pressure than pure water has. So, pure water evaporates at a much higher rate.
H
Honey has a much higher vapor pressure than water has. So, water evaporates at a much higher rate.
H
Honey has a much lower freezing point than water has. So, water evaporates at a much higher rate.
H
Honey has no vapor pressure. So, water evaporates at a much higher rate.
3

If you make a solution by dissolving 1.0 mol of FeCl3 into 1.0 kg of water, how would the osmotic pressure of this solution compare with the osmotic pressure of a solution that is made from 1.0 mol of glucose in 1.0 kg of water?

o
one-half as large
t
the same
t
twice as large
f
four times as large
4

How would the vapor pressure of a solution that contains 0.5 mol of CaCl2 in 1.0 kg of water compare with the vapor pressure of a solution that contains 1.5 mol of glucose in 1.0 kg of water?

o
one-third as large
t
the same
t
three times as large
n
nine times as large
5

A solution contains 6.21 g of ethylene glycol dissolved in 25.0 g of water. If water has a boiling point elevation constant of 0.512°C•kg/mol, what is the boiling point of the solution? (molar mass of ethylene glycol = 62.1 g/mol; boiling point of pure water = 100.00°C)Use .

Question illustration
9
97.95°C
9
99.49°C
1
100.13°C
1
102.05°C
6

The osmotic pressure of a solution increases as

t
the boiling point of the solution decreases.
t
the amount of solvent in the solution increases.
t
the number of particles of solute in the solution increases.
t
the freezing point depression constant of the solution decreases.
7

How are the boiling point and freezing point of a solvent affected when a solute is added?

B
Both the boiling point and the freezing point decrease.
B
Both the boiling point and the freezing point increase.
T
The boiling point increases, and the freezing point decreases.
T
The boiling point decreases, and the freezing point increases.
8

The freezing point of pure chloroform is -63.5°C, and its freezing point depression constant is 4.07°C•kg/mol. If the freezing point of a solution of benzoic acid in chloroform is -70.55°C, what is the molality of this solution?Use .

Question illustration
0
0.58 m
1
1.7 m
1
16 m
1
17 m
9

A student stirs 2 tablespoons of honey into a glass of water. How will the addition of honey affect the water’s colligative properties?

T
The water’s osmotic pressure and vapor pressure will both increase.
T
The water’s osmotic pressure and vapor pressure will both decrease.
T
The water’s osmotic pressure will increase, and its vapor pressure will decrease.
T
The water’s osmotic pressure will decrease, and its vapor pressure will increase.
10

Which statement about electrolytes and nonelectrolytes is not true?

N
Nonelectrolytes include all molecular compounds that do not have a full charge.
E
Electrolytes disperse as molecules in a solution.
N
Nonelectrolytes include C6H12O6 and C6H6.
E
Electrolytes dissociate into ions in the solution.

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Colligative Properties Answers — 25-26 KCS18…