Chapter 10
Solutions
101
1.
Distinguish between the terms solute and solvent. Give an example of a solution and identify each component.
The solvent is usually the substance in a solution that is in the greatest amount. A solute is a substance that is
dissolved in the solvent to make a solution.
Water is the solvent and NaCl is the solute in a salt water solution.
3.
What is the concentration of nitrate ion in each of the following aqueous solutions?
a)
0.25 M KNO
3
[NO
3
1
] =
0.25 mol KNO
3
L
×
1 mol NO
3
1
mol KNO
3
= 0.25 M
b)
0.10 M Al(NO
3
)
3
[NO
3
1
] =
0.10 mol Al(NO
3
)
3
L
×
3 mol NO
3
1
mol Al(NO
3
)
3
= 0.30 M
c)
0.20 M Ca(NO
3
)
2
[NO
3
1
] =
0.20 mol Ca(NO
3
)
2
L
×
2 mol NO
3
1
mol Ca(NO
3
)
2
= 0.40 M
5.
A solution is prepared by dissolving 25.0 g of sodium sulfate in enough water to prepare
250. mL of solution.
a)
What is the molarity of sodium sulfate in the solution?
M
m
of Na
2
SO
4
= 2 mol Na
x
23.0 g/mol + 1 mol S
x
32.0 g/mol + 4 mol O
x
16.0 g/mol = 142.0 g/mol
25.0 g Na
2
SO
4
x
1 mol Na
2
SO
4
142.0 g Na
2
SO
4
= 0.176 mol Na
2
SO
4
Molarity =
mol Na
2
SO
4
L of solution
=
0.176 mol
0.250 L
= 0.704 M
b)
What are the molarities of the sodium and sulfate ions in the solution?
[Na
1+
] =
0.704 mol Na
2
SO
4
L of solution
×
2 mol Na
1+
1 mol Na
2
SO
4
=
1.41 M
[SO
4
2
] =
0.704 mol Na
2
SO
4
L of solution
×
1 mol SO
4
2
−
1 mol Na
2
SO
4
=
0.704 M
c)
How many moles of sodium ions are present in 17 mL of the solution?
17 mL x
1+
1 L
1.41 mol Na
×
1000 mL
L
= 0.024 mol Na
1+
7.
A solution of K
2
SO
4
, which has a volume of 75.0 mL, contains 0.0048 moles of potassium ions. What is the molarity
of the K
2
SO
4
solution?
0.0048 mol K
1+
0.075 L
×
1 mol K
2
SO
4
2 mol K
1+
= 0.032 M K
2
SO
4
9.
What are the two steps involved in solvation?
Solvation consists of creating cavities in the solvent and placing the solute particles in the cavities.
11. Explain the hydrophobic effect.
The CH
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 Fall '08
 BIGHAM
 Solubility, Sodium, Sodium chloride, mol, mol Na

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