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. Suspension before settling. Suspension after settling.

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 too small 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

Mixtures Ex. (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

Mixtures Ex. (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

Mixtures Ex. (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

Mixtures All Matter Can it be separated by “physical” methods? Substance Mixture Can it be separated by “chemical” methods? Is it mixed uniformly? Heterogeneous Mixture Homogeneous Mixture CompoundElement NO YES SolutionColloid Suspension