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I February 8, 2008

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 rate 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

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.

Can be more than 2 substances

Can be more than 2 substances

Soda – carbon dioxide gas, sugar, flavorings, food coloring are dissolved in water.

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

How Does a Solution Form?

How Does a Solution Form?

1. Solvent molecules attracted to surface ions.2. Each ion is surrounded by solvent molecules.

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.

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.