Solutions Solutions

Physical ScienceMrs. Baker

Definitions Definitions

Solution - Solution - homogeneous mixture

Solvent Solvent - present in greater amount

Solute Solute - substance being dissolved

Definitions Definitions

Solute Solute - KMnO4 Solvent Solvent - H2O

Types of SolutionsTypes of Solutions

Based on state of solvent. All solid-liquid-gas combos are

possible. EX: dental amalgam (alloy of silver,

mercury, etc.)• liquid solute, solid solvent• solid solution

DissolvingDissolving

SolvationSolvation

• occurs at the surface of the solute

• solvent particles surround solute particles (+/- attraction)

• solute particles are pulled into solution

Dissolving Dissolving

NaCl dissolving in waterNaCl dissolving in water

Rate of Solution Rate of Solution

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

• more stirring

• small particle size(increased surface area)

• high temperature

Rate of SolutionRate of Solution

Gases dissolve faster…Gases dissolve faster…

• high pressure

• low temperature

“Like Dissolves Like”“Like Dissolves Like”

NONPOLAR

NONPOLAR

POLAR

POLAR

DetergentsDetergents• polar “head” with long nonpolar “tail”• can dissolve both types

Electrolytes Electrolytes

ElectrolyteNon-

Electrolyte

solute exists asions only

- +

salt

- +

sugar

solute exists asmolecules

only

- +

acetic acid

WeakElectrolyte

solute exists asions and

molecules

B. ElectrolytesB. Electrolytes

DissociationDissociation• separation of +/-

ions when an ionic compound dissolves in water

ElectrolytesElectrolytes

IonizationIonization• breaking apart of

polar covalent molecules into ions when dissolving in water

Colligative PropertiesColligative Properties

properties of solutions that depend only on solute concentration

Freezing Point DepressionFreezing Point Depression• solutes lower the f.p. of a solvent

Boiling Point ElevationBoiling Point Elevation• solutes raise the b.p. of a solvent

Colligative PropertiesColligative Properties

View Flash animation.

Freezing Point Depression

Colligative PropertiesColligative Properties

Solute particles “get in the way.”

Boiling Point Elevation

Colligative PropertiesColligative Properties

Effect increases as the solute concentration increases.

Uses:Uses:• antifreeze• making ice cream• salting icy roads

ConcentrationConcentration

Concentrated solutionConcentrated solution • large amount of solute

Dilute solutionDilute solution • small amount of solute

ConcentrationConcentration

% by Volume% by Volume• usu. liquid in liquid• EX: 10% juice = 10mL juice + 90mL water

% by Mass% by Mass• usu. solid in liquid• EX: 20% NaCl = 20g NaCl + 80g water

ConcentrationConcentration

SATURATED SOLUTION

no more solute dissolves

UNSATURATED SOLUTIONmore solute dissolves

SUPERSATURATED SOLUTION

becomes unstable, crystals form

concentration

Concentration Concentration

Percent by mass is grams of solute per total grams of solution.

Molarity is number of moles (how we count chemical substances) per Liter of solution.

SolubilitySolubility

SolubilitySolubility• maximum grams of solute that will

dissolve in 100 g of solvent at a given temperature

• varies with temperature• based on a saturated solution

SolubilitySolubility

Solubility CurveSolubility Curve• shows the

dependence of solubility on temperature

SolubilitySolubility

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).