Solutions

Definitions

Solution - Solution - homogeneous mixture

Solvent Solvent - present in greater amount~ does the dissolving.

Solute Solute - substance being dissolved

Types of Solutions

Based on state of solvent. All solid-liquid-gas combos are possible. EX: dental amalgam (alloy of liquid

mercury and a powder containing silver, tin, copper, zinc and other metals.) liquid solute, solid solvent solid solution

Nonliquid Solutions Solutions can be

gasses or solids. Example: Air you

breathe is a solution! 78% Nitrogen 21% Oxygen 1% Other gases

(argon, carbon dioxide, hydrogen…)

Example: Bronze is a solid solution of copper and tin!

Dissolving SolvationSolvation

occurs at the surface of the solute

solvent particles surround solute particles (+/- attraction)

solute particles are pulled into solution

Rate of Dissolving

Solids dissolve faster...Solids dissolve faster...

more stirring

small particle size(increased surface area)

high temperature

Rate of Dissolving

Gases dissolve faster...Gases dissolve faster...

no shaking or stirring

high pressure

low temperature

Section 2: Solubility and Concentration

Solubility SolubilitySolubility

maximum grams of solute that will dissolve in a given amount of solvent at a given temperature

Concentration Concentrated solutionConcentrated solution

large amount of solute

Dilute solutionDilute solution small amount of solute

Precise Concentrations Percent by VolumePercent by Volume

Usually liquid in liquid EX: 10% juice = 10mL juice + 90mL water

Percent by MassPercent by Mass Usually solid in liquid EX: 20% NaCl = 20g NaCl + 80g water

Concentration

SATURATED SOLUTION

no more solute dissolves

UNSATURATED SOLUTIONmore solute dissolves

SUPERSATURATED SOLUTIONbecomes

unstable, crystals form

concentration

Solubility Solubility CurveSolubility Curve

shows how solubility and temperature are related.

Solubility

Solids are more soluble at...Solids are more soluble at... high temperatures.

Gases are more soluble at...Gases are more soluble at... low temperatures. high pressures (Henry’s

Law).

Section 3Section 3

Particles in Solution

Electrolytes

ElectrolyteNon-

Electrolyte

Electrolytes are compounds that break apart in water, forming charged particles (ions) that can conduct electricity.

- +

salt

- +

sugar

- +

acetic acid

WeakElectrolyte

Electrolytes

DissociationDissociation separation of +/- ions

when an ionic compound dissolves in water

Forming Electrolytes

1. Ionization1. Ionization breaking apart of polar

covalent molecules into ions when dissolving in water

2. Dissociation Process in which an

ionic solid separates into it’s positive and negative ions.

Colligative Properties Colligative properties- properties of

solutions that depend only on solute concentration

Freezing Point DepressionFreezing Point Depression solutes lower the freezing point of a solvent

Boiling Point ElevationBoiling Point Elevation solutes raise the boiling point of a solvent

Colligative Properties

View Flash animation.

Freezing Point Depression

Colligative Properties

Solute particles “get in the way.”

Boiling Point Elevation

Colligative Properties

Effect increases as the solute concentration increases.

Uses:Uses: antifreeze making ice cream salting icy roads

Section 4Dissolving Without Water

When Water Won’t Work! Water is referred to as the “Universal

Solvent” because it can dissolve many things… But~ not everything!

Oil for example!

“Like Dissolves Like” DetergentsDetergents

polar “head” with long nonpolar “tail”

can dissolve both types

Versatile Alcohol Ethanol is a molecule that can form

solutions with both polar and non polar solutes because ethanol molecules have both a polar and a non polar end.

How Soap Works Oils on human skin and hair help them

from drying out, but oils attract and hold dirt too.

Water alone cannot remove the dirt and oil because water is polar and the oil/dirt mixture is non polar.

Soap helps because it has an ionic (charged) end that will dissolve in water, and a long hydrocarbon portion that will dissolve in oily dirt.

Polarity and Vitamins Some vitamins you need are nonpolar

(they don’t dissolve in water) These vitamins dissolve and are stored in fat! If you take too many vitamin supplements

some of these vitamins can accumulate to toxic levels in your body.