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I Lesson 1: The Nature of Solutions

Lesson 1: The Nature of Solutions

Unit 8 Solution ChemistryUnit 8 Solution Chemistry

Solution - Solution - homogeneous mixture of 2 or more substances in a single physical state

Characteristics of SolutionsCharacteristics of Solutions

Particles (atoms, ions, molecules) are very small. Particles do not scatter light Liquid solutions are clear Cannot be easily separated by simple physical means. All parts of the solution are uniform or identical

Characteristics of SolutionsCharacteristics of Solutions

A solution has 2 parts A solution has 2 parts

Solvent Solvent - present in greater amount

Solute Solute - substance being dissolved

Solute Solute - KMnO4 Solvent Solvent - H2O

Solvation Solvation

Solvation – Solvation – the process of dissolving

It is the interaction between solute and solvent particles

Energy is either required or released

Solvation Solvation

A substance that dissolves in a solvent is said to be soluble.A substance that does not dissolve in a solvent is said to be insoluble.For liquid solute-solvent combinations: 2 liquids that are soluble are miscible 2 liquids that are not soluble are immiscible

Solvation Solvation

solute particles are separated and pulled into solution

solute particles are surrounded by solvent particles

Combinations of solute and solvents.

Combinations of solute and solvents.

Solute Solvent Example

solid solid

liquid solid

Solid liquid

liquid liquid

gas liquid

gas gas

Solubility Solubility

Solubility – the ability of one Solubility – the ability of one substance to dissolve in anothersubstance to dissolve in another• maximum grams of solute that will

dissolve in 100 g of solvent at a given temperature

Solubility Solubility

SATURATED SOLUTION

no more solute dissolves

UNSATURATED SOLUTIONmore solute dissolves

SUPERSATURATED SOLUTION

becomes unstable, crystals form

concentration

Solubility Solubility

Solubility CurveSolubility Curve• shows the

dependence of solubility on temperature

Factors Affecting Solubility Factors Affecting Solubility

NONPOLAR

NONPOLAR

POLAR

POLAR

““Like Dissolves Like”Like Dissolves Like”““Like Dissolves Like”Like Dissolves Like”

1. Nature of Solute and Solvent

Factors Affecting SolubilityFactors Affecting Solubility

2. Temperature2. Temperature Solids are more soluble at...Solids are more soluble at...

high temperatures

Gases are more soluble at...Gases are more soluble at...

low temperatures

Factors Affecting SolubilityFactors Affecting Solubility

3. Pressure3. Pressure

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

(Henry’s Law).• EX: nitrogen narcosis,

the “bends,” soda

Factors Affecting SolubilityFactors Affecting Solubility

3. Pressure3. PressureHenry’s Law – At a given temperature, the solubility (S) of a gas in a liquid is directly proportional to the pressure (P) of the gas above the liquid.

S1 = S2

P1 P2

Henry’s Law ProblemHenry’s Law Problem

If 0.85 g of a gas at 4.0 atm of pressure dissolves in 1.0L of water at 25°C, how much will dissolve in 1.0L of water at 1.0 atm of pressure and the same temperature?

S1 = S2

P1 P2

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Factors Affecting the Rate of Dissolving (solvation)

Factors Affecting the Rate of Dissolving (solvation)

Factors Affecting Rate of DissolvingFactors Affecting Rate of Dissolving

1. 1. Surface AreaSurface Area Increasing surface area increases

dissolving. When the area of exposed surface is

increased, more solute particles are subjected to solvation.

Factors Affecting Rate of DissolvingFactors Affecting Rate of Dissolving

2. 2. StirringStirring Stirring increases dissolving. Without stirring, the solvent in contact with

the solute becomes saturated thereby decreasing dissolving.

Factors Affecting Rate of DissolvingFactors Affecting Rate of Dissolving

3. 3. TemperatureTemperature Increasing the temperature of solvent

increases dissolving. Increasing temperature, increases

movement of solvent particles, more solute particles are subjected to solvation.