Elements, Compounds and Mixtures

Section 3 - Mixturespp. 98-105

MIXTURES Definition: a mixture is a

combination of two or more substances that are not chemically combined.

Examples of mixtures: pizzaChicken noodle soup

PROPERTIES OF MIXTURES Each substance

in the mixture has the same chemical makeup it had before the mixture formed

METHODS OF SEPARATING MIXTURES 1. Distillation2. Using a magnet and/or

“picking parts out” by hand3. Centrifuging4. Filtration

DISTILLATION A method of separating a

mixture based on the boiling points of the components

USING A MAGNET OR REMOVING UNWANTED THINGS BY HAND

Picking out iron filings

Picking out unwanted things by hand

CENTRIFUGING A centrifuge

is a machine that separates mixtures according to their densities

FILTRATION When you filter a

substance, first you must mix it with another compound (like water).

Then you pour the mixture through a filter.

The solid is trapped by the filter.

MIXTURES Components of a mixture do not

have a definite ratio. Air is a mixture that is composed

mostly of nitrogen and oxygen. It also contains carbon dioxide and water vapor.

On some days there is more water vapor in the air than on others.

MIXTURES VS. COMPOUNDSMIXTURES COMPOUNDS

Components are elements, compounds, or both

Components are elements

Components keep their original properties

Components lose their original properties

Separated by physical means

Separated by chemical means

Formed using any ratio of components

Formed using a set mass ratio of components

TYPES OF MIXTURES

Solutions Suspensions Colloids

SOLUTIONS A mixture of two or more substances

that are evenly distributed amongst each other.

Solutions are also called homogeneous mixtures because they have the same appearance and properties throughout the mixture.

The particles in a solution are extremely small.

SOLUTIONS Examples of solutions are salt

water, perfume, tea, coffee.

SOLUTIONS (Vocabulary Terms) Dissolving: the process in which

particles of substances separate and spread evenly throughout the mixture.

Solute: the substance that is dissolved; a solute is soluble (able to be dissolved) in a solvent

Solvent: the substance that does the dissolving.

A substance that is insoluble (unable to dissolve) forms a mixture that is not a solution.

SOLUTIONS (Vocabulary Terms) Concentration – a measure of the amount

of solute dissolved in a solvent. A solution can be concentrated (when

there is more solute than solvent) or dilute (when there is more solvent than solute).

Kool-Aid that doesn’t have enough water in it is very sweet and is concentrated; Kool-Aid that has too much water in it is dilute

SOLUTIONS (Vocabulary Terms) A saturated solution is one that contains

all the solute it can hold at a given temperature.

An unsaturated solution is a solution that contains less solute than it can hold at a given temperature.

When you increase the temperature of a solution you can add more solute, supersaturating the solution.

SUSPENSIONS Suspensions are mixtures in which

particles of a material are dispersed throughout a liquid or gas but are large enough to settle out.

Suspensions are also called heterogeneous mixtures because the different components are easily seen.

SUSPENSIONS

Particles in a suspension are fairly large and can scatter light.

A suspension can be separated by passing it through a filter.

SUSPENSIONS Examples of suspensions include

Italian salad dressing and snow globes.

COLLOIDS A mixture in which particles are

dispersed throughout but not heavy enough to settle out.

The particles in a colloid are relatively small and are fairly well mixed.

Particles in a colloid can scatter light, but cannot be separated by filtration.

COLLOIDS Examples include Jell-O, whipped

cream, mayonnaise.