Cliffs AP Chemistry, 3rd Edition

Answer: A

This problem can be solved using the factor-label method:

.

..
gH O.

moles NaCl

mole NaCl

g NaCl

gH O

g NaCl

1000

10 0

1

58 50

1000

585

22

# =

The question is asking for the parts of NaCl per total solution (solute + solvent).

. g H O g NaCl

g NaCl

1000 585

585

2 +

6. When 5.92 grams of a nonvolatile, nonionizing compound is dissolved in 186 grams of
   water, the freezing point (at normal pressure) of the resulting solution is −0.592°C. What
   is the molecular weight of the compound?

A. 10.0 g/mol

B. 100. g/mol

C. 110. g/mol

D. 200. g/mol

E. 210. g/mol

Answer: B

This problem can be solved using the factor-label method:

.

1..

0 592

186

1

592

186

1000

C 1

CkgHO

mole solute

g solute

gH O

gH O

kg H O

0.0100 mol/g 100. g/mol

2

2

2

2

# : ##==

%

%

7. Calculate the number of grams of glycerol, C 3 H 5 (OH) 3 (MW = 92.1 g/mol), that must be
   dissolved in 520. grams of water to raise the boiling point to 102.00°C.

A. 5.65 g

B. 92.0 g

C. 184 g

D. 194 g

E. 204 g

Answer: C

This problem can be solved using the factor-label method:

052. :

.. g.
1

520

1000

1 1

1

92 1

1

200

184

gH O

gH O

kg H O

CkgHO

mole C H OH

mole C H OH

CH OH C

gCH OH

2

2

2

2

3 5 3

3 5 3

3

35 3

35

####

=

%

^ %

^

^

^

h

h

h

h

Solutions