Section 3-3

Section 3.3 Mixtures of Matter

• Contrast mixtures and substances.

substance: a form of matter that has a uniform and unchanging composition; also known as a pure substance

• Classify mixtures as homogeneous or heterogeneous.

• List and describe several techniques used to separate mixtures.

Section 3-3

Section 3.3 Mixtures of Matter (cont.)

Most everyday matter occurs as mixtures—combinations of two or more substances.

mixture

heterogeneous mixture

homogeneous mixture

solution

filtration

distillation

crystallization

sublimation

chromatography

Section 3-3

Mixtures

• A mixture is a physical combination of two or more pure substances in which each pure substance retains its individual chemical properties.

• A homogenous mixture is a mixture where the composition is constant throughout.

Homogeneous mixtures are also called solutions.

Examples…

C. Mixtures

• Solution– homogeneous– very small particles– no Tyndall effect

Tyndall Effect

– particles don’t settle– EX: rubbing alcohol

Tyndall Effect: The scattering of light by particles.

Section 3-3

Mixtures (cont.)

Section 3-3

Mixtures (cont.)

• A heterogeneous mixture is a mixture where the individual substances remain distinct.

• mixture is not uniform in composition

• Examples…

C. Mixtures

• Colloid– heterogeneous– medium-sized particles– Tyndall effect– particles don’t settle– EX: milk

C. Mixtures

• Suspension– heterogeneous– large particles– Tyndall effect– particles settle– EX: fresh-squeezed

lemonade

C. Mixtures

• Examples:

– mayonnaise

– muddy water

– fog

– saltwater

– Italian salad dressing

colloid

suspension

colloid

solution

suspension

Section 3-3

Separating Mixtures

• Filtration is a technique that uses a porous barrier to separate a solid from a liquid in a heterogeneous mixture.

• Distillation is a separation technique for homogeneous mixtures that is based on the differences in boiling points of substances.

• Crystallization is a separation technique for homogenous mixtures that results in the formation of pure solid particles from a solution containing the dissolved substance.

Section 3-3

Separating Mixtures (cont.)

• Sublimation is the process of a solid changing directly to a gas, which can be used to separate mixtures of solids when one sublimates and the other does not.

• Chromatography is a technique that separates the components of a mixture on the basis of tendency of each to travel across the surface of another material.

A. A

B. B

C. C

D. D

Section 3-3

A B C D

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Section 3.3 Assessment

Which is NOT a technique for separating a homogenous mixture?

A. crystallization

B. distillation

C. filtration

D. chromatography

A. A

B. B

C. C

D. D

Section 3-3

Section 3.3 Assessment

A B C D

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Which of the following is a heterogeneous mixture?

A. seawater

B. silver mercury amalgam

C. atmosphere

D. salad dressing