Solutions

Chapter 135.0 Chemistry

What is a solution

Solution: A homogeneous mixture of 2 or more substances in a single physical state.

Suspension: Particles are somewhat evenly dispersed, but will settle when at rest. (clay & water)

Colloid: Particle size between suspension and solution (milk)

Properties of Solutions

Small Particles

Evenly distributed particles

Particles do not separate when at rest.

Solubility: The ability to dissolve in another substance.

Properties of Solutions

Solute: substance that is dissolved

Solvent: Substance that does the dissolving

Solute

Solvent

Properties of Solutions

Soluble means something can be dissolved in something else.

Insoluble means something cannot be dissolved in something else.

Solid Solutions

Alloys: Solid solutions that contain 2 or more pure substance.

Advantages of alloys over pure metals: Stronger Cheaper Resistance from corrosion Lighter

Alloys

Gaseous Solutions

The properties of gaseous solutions depend on the properties of its components.

Ex. Air

Liquid Solutions

Miscible Liquids: 2 liquids that can mix together in any amount

Ex. Alcohol and water

Liquid Solutions

Immiscible Liquids: 2 liquids that cannot mix

Ex. Oil and Water

Other types of solutions

Aqueous Solutions: Solutions with water as the solvent.

Because water can dissolve so many things, it is called the universal solvent.

Electrolyte: A solution that conducts electricity

Tincture: Solutions with alcohol as the solvent.

Type of Solution Specific Solute Specific Solvent

Gas in Gas

Air O2 N2

Gas in Liquid

Soda CO2 H2OGas in Solid

catalytic converter hydrocarbons PtLiquid in Gas

fog H2O airLiquid in Liquid

Lemonade lemon juice waterLiquid in Solid

teeth fillings mercury silverSolid in Gas

smoke carbon airSolid in Liquid

Kool-Aid sugar waterSolid in Solid

steel carbon iron

IN

Concentration and Molarity

Concentration: Refers to the amount of solute per given amount of solvent.

Dilute Solutions – Has little solute

Concentrated Solutions – Has large amount of solute

Molarity

Molarity – Term used for concentration

Molarity = Moles of Solute

Liters of Solution

D. Molarity: (M)

Ex #1) What is the molarity of a solution formed by mixing 10.0 g of sulfuric acid with enough water to make 100.0 mL of solution?

moles of solutemolarity =

liters of solution

n mol = units =

V LM

2 410.0 g H SO 2 4

2 4

1 mol H SO

98 g H SO2 4 = 0.102 mol H SO

2

0.102 mol = 1.02

0.1000 L H OM M

Ex #2) How many grams of bromine are needed to prepare 0.500 L of a 0.0100 M solution of bromine in water?

2

n0.0100 = n = 0.00500 mol Br

0.500 LM

20.00500 mol Br 2160 g Br

1 mol Br2

2

= 0.800 g Br

Solubility and the Dissolving Process

Saturated: A solution is saturated if it contains as much solute as can possibly be dissolved under existing conditions of temperature and pressure.

Unsaturated: Has less than the maximum amount that can be dissolved.

Supersaturated: Has more than the maximum amount that can be dissolved.

Saturated vs. Unsaturated

Saturated vs. Unsaturated

Supersaturated

Dilutions

Formula for Dilutions: M1V1 = M2V2

How a solution forms Process of dissolving takes place at the

surface of the solute.

Dissolving Process

The interaction between the solute and solvent to allow ions to separate is called solvation. This interaction is called hydration when water is the solvent.

Dissolving Process

Energy is absorbed when the bonds break. (endo)

Energy is released when bonds form. (exo)

Solubility

Solubility is amount of solute that will dissolve in a specific solution under given conditions.

See solubility curves

Solubility Graph for NaNO3

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

0 10 20 30 40 50 60 70 80 90 100 110

Temperature (deg C)

So

lub

ilit

y (

g/1

00 g

wat

er )

Saturated sol’n

Supersaturated solution

Unsaturated solution

At 20 oC, a saturated solution contains how many grams of NaNO3 in 100 g of water?

What is the solubility at 70 oC? 135 g/100 g water

What kind of solution is formed when 90 g NaNO3 is dissolved in 100 g water at 30 oC?

unsaturated

What kind of solution is formed when 120 g NaNO3 is dissolved in 100 g water at 40 oC?

supersaturated

90 g

Factors that affect solubility

1) Nature of Solute and Solvent General rule: Like dissolves Like See example

2) Temperature As temperature increases, the solubility of

gases and liquids decrease.

Gases are less soluble at high temperatures than at low temperatures.

Pressure: As pressure increases, the solubility increases.

Factors Affecting the Rate of Dissolving

1) Surface Area 2) Stirring 3) Temperature

Altering these 3 factors will either increase the frequency of collisions or the energy of collisions between the solute and solvent.