Mixtures

Mixtures• A mixture is a form of matter that is composed of

two or more elements, two or more compounds, or of elements and compounds.

Mixtures• In a mixture, the individual components

USUALLY retain their own individual properties.

• In air, nitrogen, oxygen, argon, and other gases all retain their own individual properties.

Mixtures• The components of a mixture are physically

combined and need NOT be composed in a definite (unique) ratio.

Mixtures• A mixture is not a substance because all samples

are not necessarily alike in composition.

Does the salt and water mixture on the left have

to be made in the same

ratio as the one on the

right?

Mixtures• A mixture can be either homogeneous or

heterogeneous.

• A homogeneous mixture is one in which all of the components are UNIFORMILY distributed.

• A heterogeneous mixture is one in which the components are NOT UNIFORMILY distributed.

HOMOGENEOUS HETEROGENEOUS

Mixtures• Solutions are the ONLY type of homogeneous

mixtures!

• All mixtures of two or more different gases are homogeneous and thus solutions.

Mixtures• Filtering cannot separate a solution because

the components are too small.

Mixtures• A solution will not separate if left standing.

Mixtures• A beam of light will not be diffracted when passed

through a liquid or gaseous solution and thus will remain unseen.

a solutionnot a solution

Mixtures• Alloys are also solutions because they are a

homogeneous mixture of two or more metals!

• ALLOYS ARE NOT COMPOUNDS BECAUSE THE ELEMENTS DO NOT HAVE TO BE IN A UNIQUE RATIO!

• Brass, bronze, and steel are examples of alloys.

Mixtures• All other types of mixture are heterogeneous

because the components are not uniformly (evenly) distributed.

• Suspensions and colloids are two examples of heterogeneous mixtures.

Mixtures• A suspension is a heterogeneous mixture in

which some of the component particles are large enough to be seen by the naked eye and which will separate when left standing.

Suspensionbefore

settling.

Suspensionaftersettling.

Mixtures• A colloid is a heterogeneous mixture in which

the components are microscopic (the particles can’t be seen by the eye) and will not separate when left standing.

In this colloidal silver mixture,the particles of silver are toosmall to be seen with the naked eye.

Mixtures• A colloid can be distinguished from a solution by

shining a light beam through the sample. If the light can be seen, then the same is a colloid.

a solution a colloid

MixturesEx. (1) A mixture of nitrogen gas, oxygen gas, and

argon gas is classified as (1) an element (2) a compound (3) a homogeneous mixture

(4) a heterogeneous mixture

Ex. (2) The alloy bronze is composed of copper and tin. Bronze is classified as

(1) an element (2) a compound (3) a homogeneous mixture

(4) a heterogeneous mixture

MixturesEx. (3) Brine is a solution of salt and water. Brine is

classified as (1) an element (2) a compound (3) a homogeneous mixture

(4) a heterogeneous mixture

Ex. (4) Which class of matter cannot be separated by either a physical method or a

chemical method? (1) an element (2) a compound (3) a homogeneous mixture

(4) a heterogeneous mixture

MixturesEx. (5) Which class of matter can be separated by a

chemical method but not by a physical method?

(1) an element (2) a compound (3) a homogeneous mixture

(4) a heterogeneous mixture

Ex. (6) In which class of matter can the components usually be separated by filtering?

(1) an element (2) a compound (3) a homogeneous mixture

(4) a heterogeneous mixture

MixturesAll Matter

Can it beseparated by

“physical” methods?

Substance Mixture

Can it beseparated by “chemical” methods?

Is it mixed uniformly?

Heterogeneous Mixture

Homogeneous Mixture

CompoundElement

NO

NO NO

YES

YES YES

SolutionColloid Suspension