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Chapter 15

True/False
Indicate whether the sentence or statement is true or false.
 

1. 
Increasing temperature always increases the solubility of a solute in a solvent.
 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

2. 
In a solution, the substance that is being dissolved is the _____.
a.
gas
c.
solute
b.
liquid
d.
solvent
 

3. 
The oceans are an example of _____ solution.
a.
an anhydrous
c.
a liquid
b.
a gaseous
d.
a solid
 

4. 
A substance that does NOT conduct an electric current when it forms a solution is _____.
a.
an electrolyte
c.
a nonpolar substance
b.
a nonelectrolyte
d.
a polar substance
 

5. 
A solution that contains all the solute it can hold at a given temperature is _____.
a.
diluted
c.
supersaturated
b.
saturated
d.
unsaturated
 

6. 
The process by which the positive and negative ions of an ionic compound separate in water is called _____.
a.
dissociation
c.
polarity
b.
ionization
d.
saturation
 

7. 
Increasing the surface area of a solid _____.
a.
causes the solid to ionize
c.
slows the rate of solution
b.
has no effect on the rate of solution
d.
speeds the rate of solution
 

8. 
When a gas is dissolved in a liquid, the gas dissolves faster if the liquid is _____.
a.
cooled
c.
heated
b.
an electrolyte
d.
under low pressure
 

9. 
The concentration of a solution that contains much solute in the solvent could be described as _____.
a.
concentrated
c.
polar
b.
diluted
d.
unsaturated
 

10. 
An alloy is an example of a _____ solution.
a.
dilute
c.
liquid
b.
gaseous
d.
solid
 

11. 
Adding more solute to a solvent _____.
a.
decreases its boiling point
c.
increases its boiling point
b.
does not affect its boiling point
d.
increases its freezing point
 

12. 
When placed in water, some covalent compounds _____.
a.
become radioactive
c.
form protons
b.
dissociate
d.
ionize
 

13. 
Solutions of electrolytes and metals are _____.
a.
conductors
c.
negative
b.
insulators
d.
polar
 

14. 
A molecule that is positively charged on one end and negatively charged on the other end is _____.
a.
ionic
c.
polar
b.
magnetic
d.
radioactive
 

15. 
The amount of solute that can be dissolved in a specific amount of solvent at a given temperature is its _____.
a.
concentration
c.
dilution
b.
density
d.
solubility
 

16. 
Which of the following combinations would increase the solubility of a gas in a liquid?
a.
Decrease the pressure and decrease the temperature.
b.
Decrease the pressure and increase the temperature.
c.
Increase the pressure and decrease the temperature.
d.
Increase the pressure and increase the temperature.
 

17. 
Which of the following will speed up the dissolving of a solid solute in water?
a.
Cool the solution.
c.
Grind up the solvent.
b.
Freeze the solute.
d.
Stir the solution.
 

18. 
Organic solvents are substances that _____.
a.
are usually odorless
c.
do not vaporize
b.
cannot be absorbed through skin
d.
are found in paints
 

19. 
The government agencies CPSC      and OSHA have all the following functions except to _____.
a.
regulate the use of organic solvents by do-it-yourselfers
b.
label chemicals that are flammable or corrosive
c.
require limits to the exposure to organic solvents by employees of building contractors
d.
fine contractors whose workers are exposed for long periods of time to organic solvents
 

20. 
Which of the following is the correct expression for concentration in terms of percent by mass?
a.
  mass of solute   
volume of solution x 100
b.
  mass of solute
mass of solution x 100
c.
volume of solute
volume of solvent x 100
d.
  mass of solute  
volume of solution ¸ 100
 

Completion
Complete each sentence or statement.
 

21. 
A crystal of solute was dropped into a solution, and it dissolved. The original solution was _______________.
 

 

22. 
If a crystal of solute is dropped into a solution and other crystals appear, the solution was _______________.
 

 

23. 
Stirring _______________ the rate of dissolving of a solid in a liquid.
 

 

24. 
Stirring _______________ the rate of dissolving of a gas in a liquid.
 

 

25. 
Decreasing temperature _______________ the rate of solution for a gas in a liquid.
 

 

26. 
Good ventilation is required when working with materials that contain _______________ solvents.
 

 

Short Answer
 

27. 
Explain how the adding of a substance, such as antifreeze, to water decreases the freezing point of the water.
 

28. 
Explain why increasing the surface area of a solid solute helps to dissolve it more quickly.
 

29. 
Explain why the ocean is considered a solution.
 

30. 
Explain why cities put salt on icy streets.
 

31. 
List three types of solutions and give an example of each.
 
 
chapter_15_files/i0360000.jpg
 

32. 
According to Figure 15-1, how many grams of KBr are needed to make a saturated solution in 100 g of water at 30ºC?
 

33. 
Using Figure 15-1, how would you classify a KBr solution with a concentration of 90 g/100 g of water at 50ºC in terms of saturation?
 

34. 
From Figure 15-1, the solubility of which salt is least affected by temperature?
 

35. 
From Figure 15-1, which salt is more soluble in water, KCl or KBr?
 

36. 
According to Figure 15-1, at what temperature is the solubility of KBr the same as that of KNO3?
 

37. 
According to Figure 15-1, how many grams of KCl will form a saturated solution in 100 g of water at 60ºC?
 

Problem
 

38. 
How many grams of NaCl would have to be added to make a 100-mL water solution that is 20 percent NaCl by mass?
 

39. 
How many grams of water are needed to make 100 g of a 20 percent saltwater solution?
 

40. 
If 1.0 L of solution contains 45 g of solute, how many grams of solute are contained in 200 mL of the same solution?
 



 
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