November 19, 2009

SolutionsSolutions

ObjectivesObjectives

1. Define solution, solubility, insoluble, solute and solvent

2. Name the universal solvent

3. Distinguish between an aqueous solution and a tincture

4. Identify the factors that affect rates of solubility

SolutionSolution

A mixture that appears to be a single substance but is made up of 2 or more substances that are evenly distributed throughout the mixture

CharacteristicsCharacteristics

Homogeneous

Best mixed of the mixtures

Particles are dissolved

Solutions are made up ofSolutions are made up of

Solutes – the substance that is dissolved

Solvents – the substance that does the dissolving. It is always present in greater amount.

Solubility – the physical property of being able to dissolve

Insoluble – a substance that can not be dissolved

Water is the universal solvent. Most things will dissolve in water. It is called an aqueous solution.

Sometimes the solvent is alcohol. In this case it is called a tincture.

Usually solutions are substances dissolved in a liquid but solutions may also be gasses and solids.

Solution rates varySolution rates vary

TemperatureSurface areaMovementPressure

TemperatureTemperature

The solubility of solid solutes in liquid solvents increases with increasing temperature.

TemperatureTemperature

The opposite is true of gases. Higher temperature drives gases out of solution.

Carbonated soft drinks are more “bubbly” if stored in the refrigerator.

Warm lakes have less O2 dissolved in them than cool lakes.

Surface areaSurface area

The larger the surface area of a solid, the faster the rate of dissolving. The surface area of an object increases when it is broken down into smaller pieces.

MovementMovement

When a substance dissolves, it fills the available spaces between the closest water molecules. Stirring increases the rate the empty spaces can be filled.

PressurePressure

The solubility of liquids and solids does not change with pressure.

Increased pressure increases the solubility of gases.