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