Solutions

Definitions:Definitions: solutionssolutionsA solution is a A solution is a

HOMOGENEOUSHOMOGENEOUS mixture of 2 or more mixture of 2 or more substances mixed substances mixed evenly at molecular evenly at molecular level.. level..

One part is regarded as One part is regarded as the the SOLUTESOLUTE and the and the others as others as SOLVENTSOLVENT

Parts of a Solution1. Solute-the part that gets dissolved2. Solvent-the part that does the

dissolving

Parts of a Solution

SOLUTESOLUTE –material being dissolved (usually the lesser amount)

SOLVENTSOLVENT – material doing the dissolving (usually the greater amount)

Solute + Solvent = Solute + Solvent =

SolutionSolution

Solute

Solvent Example

solid solid Alloys (brass, steel)

solid liquid Salt water

gas solid Air bubbles in ice cubes

liquid liquid Mixed drinks

gas liquid Soft drinks

gas gas Air

Solution Definitions1. Soluble - capable of being dissolved

2. Solution – homogeneous mixtures

3. Saturated – exactly the right amount of dissolved solute for a particular solvent

4. Unsaturated –less solute than can be dissolved by a solvent to be saturated

5. Supersaturated -more dissolved solute than saturated. Has to be specially made; unstable

Factors Affecting Solubility

“Like Dissolves Like”

A polar solvent, such as water, will dissolve polar and ionic solutes. Nonpolar solvents, such as oils, will dissolve other nonpolar solutes.

Factors Affecting Solubility

Temperature

1) Solids in a liquid - increasing temperature increases solubility (mostly).

2) Gases in a liquid- increasing temperature decreases solubility.

Factors Affecting Solubility

Pressure

1) Increasing pressure increases the solubility of a gas in liquids. Ex. Carbonated drinks

2) Pressure has little/no effect on the solubility of a solid in a liquid.

Factors that affect dissolving of solids in a liquid

1. Surface area - Increase of surface area increases rate of dissolving. Increase surface area by breaking/grinding solid

2. Agitation – Shaking/stirring a solution will increase the rate of dissolving

3. Heat- increase in temperature usually increases the rate of dissolving

Some solutions conduct electricity, some don’t

Electrolytes – compounds that conduct an electric current in an aqueous solution OR in the molten state.

An electrolyte solution contains charged particles (ions), which can move. Any salt dissolved in water is an

electrolyte: NaCl, KI, etc.

Types of Electrolytes

Strong electrolytes– a large portion of the solute exists as ions, such as aqueous solutions of all ionic compounds

Weak electrolytes– these are solutions in which only a small portion of the solute exists as ions

Non-electrolytes- compounds that do NOT conduct electricity in either aqueous solution of melted

a. distilled water b. Gasesc. molecular compounds

(2 nonmetals)d. organic compounds – alcohols, sugars, etc. anything containing a carbon.

Practice:

• Identify the solute and solvent in the following solutions:

a) 10.0 g of sugar & 40.0 g of water

solute: ____________solvent: ___________

b) 75 g of KBr & 100 g water

solute: ____________solvent: ___________

3. Based on the solubility chart below, decide whether each of the following is U: unsaturated(Under line), S: saturated (on line), SS: supersaturated (above line), or N: not enough information is given.

a) 50 g KCl in 100 g of water at 90°C. ____

b) 50 g KCl in 100 g of water at 60°C. ____

d) 50 g KNO3 in 50 g of water at 60°C. ____

50 g KNO3 = X X = 100

50 g water 100 g water

Practice:5. Circle the correct type for the

following solutions:

a) NaCl (aq): electrolyte or nonelectrolyte

b) CCl4 (l): electrolyte or nonelectrolyte