Mixture

From Wikipedia, the free encyclopedia

A mixture in chemistry is the product of a mechanical blending or mixing of chemical substances like elements and compounds, without chemical bonding or other chemical change, so that each ingredient substance retains its own chemical properties and makeup ^[1] . While there are no chemical changes in a mixture, physical properties of a mixture, such as its melting point, may differ from those of its components. Mixtures can usually be separated by mechanical means.

There are three different types of mixtures: homogeneous mixtures (also called solutions), heterogeneous mixtures, and colloidal dispersions.

Contents 1 What is A Mixture? 2 Homogeneous mixtures 2.1 Solutions 3 Heterogeneous mixtures 4 Colloidal dispersions 5 References

[edit] What is A Mixture?

A mixture is: 1. made up of two or more substances, 2. are not chemically combined 3. can be seperated by physical means

Added: 31st March 2007

      K.Sheahan

[edit] Homogeneous mixtures

Homogeneous are mixtures that have definite, true composition and properties. For example, any amount of a given mixture has the same composition and properties. Examples are solutions and some alloys (but not all). Homogeneous mixtures can also be called "impure substances." A homogeneous mixture is a uniform mixture consisting of only one phase. Examples are gasoline and margarine.

[edit] Solutions

Main article: Solution

One type of homogeneous mixture is a solution. A solution is a substance homogeneous mixture of two or more substances (the solutes) dissolved in another substance (the solvent). A common example would be a solid dissolving into a liquid (i.e. salt or sugar dissolving in water or gold into mercury). Liquids dissolve into one another, and sometimes liquids dissolve into gases, for example water vapor and the atmosphere. Common examples include soft drinks (like Coca-Cola and Sprite), where carbon dioxide is trapped in the soda through carbonation. Several solution properties collectively called colligative properties change as a function of solute concentration. Solubility is a compound property

[edit] Heterogeneous mixtures

Heterogeneous mixtures are mixtures without definite composition, for example, granite. Salad is a typical example of this kind of mixture. Heterogeneous mixtures are said to have several phases (not to be confused with phases of matter). An example is the parts of a heterogeneous composition, which can be mechanically separated from the rest. Examples include: salad, trail mix, milk (before homogenization).

[edit] Colloidal dispersions

Main article: Colloid

In general, a colloid or colloidal dispersion is a substance with components of one or two phases, a type of mixture intermediate between a homogeneous mixture and a heterogeneous mixture with properties also intermediate between the two. A colloid will not settle if left to sit. Examples are jello and glue. A suspension is a type of colloid.

[edit] References