COS 2.0, 2.1, 2.2, 2.3

• IDENTIFY SOLUTIONS IN TERMS OF COMPONENTS, SOLUBILITY, CONCENTRATION, AND CONDUCTIVITY.

• COMPARE SATURATED, UNSATURATED AND SUPERSATURATD SOLUTIONS.

• COMPARE CHARACTERISTICS OF ELECTROLYTES AND NONELECTROLYTES.

• DESCRIBE FACTORS THAT AFFECT SOLUBILITY AND RATE OF SOLUTION, INCLUDING NATURE OF SOLUTE AND SOLVENT, TEMPERATURE, AGITATION, SURFACE AREA AND PRESSURE ON GASES.

WHAT YOU’LL LEARN • Compare the properties of suspensions, colloids, &

solutions.

• Explain the meaning of solubility & compare the solubilities of various substances.

• Examine the factors that affect the rates at which solids and gases dissolve in liquids.

• Explain how solvents work.

• Compare & contrast saturated, unsaturated, & supersaturated solutions.

SOLUTIONSSOLUTIONS homogeneous mixture of two or more homogeneous mixture of two or more

substances uniformly dispersed in a substances uniformly dispersed in a single phasesingle phase

SOLUTES & SOLVENTS

PARTS OF A SOLUTION

SOLUTE part of a solution that is being dissolved (lesser

amount/%)

SOLVENT part of a solution that dissolves the solute (greater

amount/%) Solute + Solvent = Solution

EXAMPLES air: 78% nitrogen, 21% oxygen sterling silver: 92.5% silver, 7.5% copper

ALLOYS

• mixture of a metal with one or more elements that retains original properties.

• made by melting metal solute & solvent together

• Examples: coins, brass, sterling silver

SOLUBILITY IN WATER

Concentration

• amount of a particular substance in a given volume of solution

Concentrated

• solution whose ratio of solute to solvent is relatively high

Dilute

• solution whose ratio of solute to solvent is relatively low

Solubility

• max amount of a solute that will dissolve in a given quantity of solvent at a given temperature and pressure.

Insoluble

• never dissolves, such as oil

Soluble

• easily dissolves in water

• limit to how much of a substance will dissolve.

• different substances have different solubilities.

Solvation

• combination of solvent molecules with molecules or ions of the solute

Miscible

• two or more liquids that can dissolve into each other in various proportions

• example: gasoline (100 liquids)

Immiscible

• two or more liquids that do not mix with each other

• example: oil & water

HOW THINGS DISSOLVE

• water molecules are constantly moving• water molecules are polar • has oppositely charged ends (+ and -)• non-polar• have same charges on its ends• negative-positive areas attract

“breaking” bonds

RULE FOR DISSOLVING SOLUTES IN A SOLVENT

• Like solutes dissolve in like solvents • (polar in polar, non-polar in non-

polar)

RATE OF DISSOLVING

SURFACE AREA SURFACE AREA (CRYSTAL SIZE)(CRYSTAL SIZE)• dissolving takes place at

surface area• smaller crystals dissolve

faster• increases surface area• more surface area faster

dissolving• less surface area slower

dissolvingExample: piece of candy

TEMPERATURE

• increasing temperature speeds up molecule movement

• increase in speed causes more solvent particles to “bump” into solute breaking them down

• lower temperature slows down process

• Example: sugar in hot water

PRESSURE

• affects solubility of gases in liquids

Gases are more soluble at...Gases are more soluble at...• low temperatures.• high pressures

Example: • Soda goes flat quickly at room temperature

carbon dioxide gas escapes

AGITATION

• AKA: mixing or stirringAKA: mixing or stirring• increase in stirring causes more solvent increase in stirring causes more solvent

particles to “bump” into soluteparticles to “bump” into solute• causing more solute to dissolvecausing more solute to dissolve• Example: sugar in waterExample: sugar in water

TYPES OF SOLUTIONS

UNSATURATED

contains less than max amount of solute that can dissolve at a particular temperature

UNSATURATED SOLUTIONmore solute dissolves

SATURATED

contains max quantity of solute that dissolves at that temperature.

SATURATED SOLUTION

no more solute dissolves

SUPERSATURATED

contain more solute than is possible to be dissolvedare unstable. supersaturation is only temporary, and usually accomplished in one of two ways:Warm solvent so that it will dissolve more, then cool the solution Evaporate some of solvent carefully so that the solute does not solidify and come out of solution.

SUPERSATURATED SOLUTION

becomes unstable, crystals form

HETEROGENOUS HETEROGENOUS MIXTURESMIXTURES

Suspension

mixture in which the solute particles are large enough to be seen

Particles may settle over time or filtered out Example: natural orange juice, which

contains particles of pulp.

Suspension

Colloids

mixture whose particles never settle Examples: milk, paint

ELECTROLYTES & ELECTROLYTES & NONELECTROLYTESNONELECTROLYTES

AQUEOUS SOLUTIONSAQUEOUS SOLUTIONS

Solution in which solvent is water (most Solution in which solvent is water (most common)common)

Electrolytes

substance that dissolves in water to give a solution ability to conduct an electric current.

Examples: sodium chloride and silver nitrate

- +

salt

Nonelectrolytes

substances that dissolve in water that does not conduct electricity

sugar, alcohol, benzene

- +

sugar

Electrolytes in the BodyElectrolytes in the Body

Carry messages to Carry messages to

and from brain as and from brain as

electrical signalselectrical signals

Maintain cellular Maintain cellular

function with correct function with correct

concentrations concentrations

electrolyteselectrolytes

Make your ownMake your own

50-70 g sugar50-70 g sugarOne liter of warm One liter of warm

waterwaterPinch of saltPinch of salt200ml of sugar 200ml of sugar

free fruit squashfree fruit squashMix, cool and drinkMix, cool and drink