 Most common solvent
 A polar molecule

a hydrogen bond

+

+

Solutions are homogeneous mixtures of two or more substances
 Solute
The substance in the lesser amount
 Solvent
The substance in the greater amount

 Spread evenly throughout the solution
 Cannot be separated by filtration
 Can be separated by evaporation
 Not visible, solution appears transparent
 May give a color to the solution

air O
2 gas and N
2 gas gas/gas soda CO
2 gas in water gas/ liquid seawater NaCl in water solid / liquid brass copper and zinc solid/solid
(alloy)

Identify the solute and the solvent.
A. brass: 20 g zinc + 50 g copper solute = 1) zinc 2) copper solvent = 1) zinc 2) copper
B. 100 g H
2
O + 5 g KCl solute = 1) KCl 2) H
2
O solvent = 1) KCl 2) H
2
O

A. brass: 20 g zinc + 50 g copper solute = 1) zinc solvent = 2) copper
B. 100 g H
2
O + 5 g KCl solute = 1) KCl solvent = 2) H
2
O

Identify the solute in each of the following solutions:
A. 2 g sugar (1) + 100 mL water (2)
B. 60.0 mL ethyl alcohol (1) and 30.0 mL of methyl alcohol (2)
C. 55.0 mL water (1) and 1.50 g NaCl (2)
D. Air: 200 mL O
2
(1) + 800 mL N
2
(2)

Identify the solute in each of the following solutions:
A. 2 g sugar (1)
B. 30.0 mL of methyl alcohol (2)
C. 50 g NaCl (2)
D. 200 mL O
2
(1)

A ____________ solvent such as water is needed to dissolve polar solutes such as sugar and ionic solutes such as NaCl.
A ___________solvent such as hexane
(C
6
H
14
) is needed to dissolve nonpolar solutes such as oil or grease.

 A saturated solution contains the maximum amount of solute that can dissolve.
Undissolved solute remains.
 An unsaturated solution does not contain all the solute that could dissolve

At 40

C, the solubility of KBr is 80 g/100 g
H
2
O. Indicate if the following solutions are
(1) saturated or (2) unsaturated
A. ___60 g KBr in 100 g of water at 40

C
B. ___200 g KBr in 200 g of water at 40

C
C. ___25 KBr in 50 g of water at 40

C

At 40

C, the solubility of KBr is 80 g/100 g
H
2
O. Indicate if the following solutions are
(1) saturated or (2) unsaturated
A. 2 Less than 80 g/100 g H
2
O
B. 1 Same as 100 g KBr in 100 g of water at 40

C, which is greater than its solubility
C. 2 Same as 60 g KBr in 100 g of water, which is less than its solubility

Which of the following solutes will dissolve in water? Why?
1) Na
2
SO
4
2) gasoline
3) I
2
4) HCl

Which of the following solutes will dissolve in water? Why?
1) Na
2
SO
4
Yes, polar (ionic)
2) gasoline No, nonnpolar
3) I
2
4) HCl
No, nonpolar
Yes, Polar

The maximum amount of solute that can dissolve in a specific amount of solvent usually 100 g.
g of solute
100 g water

Temperature Solubility (g/100 g H
2
O)
0 °
20 °C
KCl(s)
27.6
34.0
NaNO
74
88
3
(s)
50 °C
100 °C
42.6
57.6
114
182
The solubility of most solids ( decreases or increases ) with an increase in the temperature.

Temperature Solubility (g/100 g H
2
O)
0 °
20 °C
KCl(s)
27.6
34.0
NaNO
74
88
3
(s)
50 °C
100 °C
42.6
57.6
114
182
The solubility of most solids increases with an increase in the temperature.

Temperature Solubility (g/100 g H
2
O)
CO
2
(g) O
2
(g)
0.34
0.0070
0 °C
20 °C
50 °C
0.17
0.076
0.0043
0.0026
The solubility of gases (decreases or increases) with an increase in temperature.

Temperature Solubility (g/100 g H
2
O)
CO
2
(g) O
2
(g)
0.34
0.0070
0 °C
20 °C
50 °C
0.17
0.076
0.0043
0.0026
The solubility of gases decreases with an increase in temperature.

A. Why would a bottle of carbonated drink possibly burst (explode) when it is left out in the hot sun ?
B. Why would fish die in water that gets too warm?

Properties of Solutions
1. homogeneous mixture if stirred during its formation
2. dissolved particles remain dissolved regardless of the time interval
3. a solution is clear and transparent
4. dissolved particles are extremely small allowing for the solution to be filtered
5. considered to be a single phase

Types of Solutions
1. Gas/Gas
2. Liquid/Gas
3. Liquid/Liquid
4. Liquid/Solid
5. Solid/Solid a. alloys b. amalgams

Terms to know:
1. solute - the substance being dissolved to form a solution; usually in the lesser amount
2. solvent - the medium in which the solute is being dissolved; usually in the greater amount
3. tincture - a solution in which the solvent is alcohol
(alcohol usually means ethanol or ethyl alcohol which has the formula, C
2
H
5
OH)
4. unsaturated - contains less solute that it is capable of holding
5. saturated - contains the maximum amount of solute that it is capable of holding
6. supersaturated - contains more solute that it is capable of holding; metastable state which quickly returns to a saturated solution
7. solubility - the amount of a solute that can be dissolved in a given amount of solvent
8. solubility curve - a plot which shows the amount of solute that can be dissolved in a given amount of solvent and temperature

Factors affecting Solubility
1. Nature of the solute and solvent: the expression, "Like dissolves like", describes this very well
2. Temperature - usually an increase in temperature will increase the solubility of a solute in a given solvent. There are exceptions to this rule, but they are rare.
3. Pressure - affects only gaseous solutions, those in which both the solute and solvent are gases and those in which one component is a gas and the other is a liquid

Factors Affecting the Rate of Solution
1. Size of the particles - in chemistry we call this the surface area; the larger the surface area, the easier it is for a solute to dissolve
2. Stirring - more stirring increases the contact between the solute and solvent and increases the rate of solution
3. Amount of solute already dissolved - as the solute continues to dissolve, the solution will begin to approach the saturated state and the rate of dissolving will slow down
4. Temperature - for liquids and solids, an increase will cause more solute to dissolve and to dissolve at a faster rate; the opposite is true for gas solutions