Pure Substances and Mixtures

Review Notes for Quiz

THE PARTICLE THEORY Everything is made of particles with spaces

between them, particles are always moving and particles are attracted to each other.

SOLIDS: Particles are close together, very attracted to each other, locked in a pattern and vibrate in place.

LIQUIDS: Particles are slightly farther apart, less attracted to each other and are able to slide past each other.

GAS: Particles are far apart and can move in any direction because the attractive forces are weak.

PURE SUBSTANCES AND MIXTURES

A pure substance contains only 1 type of particle throughout (Diamonds, distilled water). Pure substances rarely occur naturally and most are separated from raw material by people.

A mixture contains 2 or more types of particles (2 or more pure substances) throughout (air, salt water, salad). Most substances are mixtures.

TYPES OF MIXTURES

Heterogeneous mixtures (mechanical mixtures) are made up of 2 or more types of particles and you can see or feel the different types of particles (ex. strawberry jam, salad)

Homogeneous mixtures (solutions) are made up of 2 or more types of particles but look and feel like only 1 type of particle (ex. apple juice, sugar and water).

Solutions are made up of at least one solute and one solvent.

The solute is the substance that gets dissolved (kool-aid powder).

The solvent is the substance that does the dissolving (water).

Solutions can be made up of any combination of solid, liquid or gas (eg Pop is made up of liquid water, solid sugar and gaseous carbon dioxide).

HOW DO SOLUTIONS FORM?

When particles of one substance are more attracted to particles of another substance than they are to themselves, they will form a solution.

In this situation, particles on the surface of the solute will break away and begin to fill the spaces between the solvent particles until all the solute particles are evenly mixed between the solvent particles.

THE RATE OF DISSOLVING

The rate of dissolving refers to how fast a solute dissolves (mixes) in a solvent.

We discovered 3 factors that increase the rate of dissolving: movement (stirring), increasing the solvent temperature and crushing the solute.

Dilute/ConcentratedThe concentration of a substance is how

much solute there is compared to solvent. A solution with a low concentration is

dilute.A solution with a high concentration is

concentrated.Concentration can be calculated using the

formula: Amount of Solute x100 Amount of SolventConcentration is measured in percent

Saturated/Unsaturated

Saturated: When there are no more spaces between the solvent particles for solute particles to dissolve. No more solute can dissolve in the solvent

Unsaturated: When there are still spaces between the solvent particles for more solute particles to dissolve into the solvent.

Supersaturated: A solution that contains more of the solute than would normally be found in a saturated solution at that temperature. This is created by heating a solvent and saturating it, and then slowly cooling it without disturbing the solution so that the solute stays dissolved at the cooler temperature.

Solubility: The amount of solute that will dissolve in a particular solvent at a certain temperature. Sugar has a higher solubility than salt because more sugar can dissolve in 100mL of water than salt at the same temperature. This is because sugar particles are smaller than salt particles.

Household Hazardous Waste Symbolssee page 55

Red/Danger Orange/Warning Yellow/Caution

WHMIS Symbolssee page 55

WHMIS stands for Workplace Hazardous Materials Information System.