Mixture- matter that consists of two or more substances mixed together but not chemically combined. A mixture is a combination of substances. Each substance that makes up a mixture has it own specific properties and is the same throughout. The substances in a mixture are not chemically combined. The substances keep their separate identities and most of their own properties. Substances in a mixture may change in physical appearance, as when they dissolve. But the substances do not change in chemical composition. In a sugar-water mixture, the same particles of water and sugar are present after the mixing as before it. No new chemical substances have been formed. Another property of a mixture is that the substances that make up a mixture can be present in any amount. The amounts are not fixed. A iron and baking soda mixture may be 1/3 iron and 2/3 baking soda, or 1/2 iron and 1/2 baking soda. Both are iron-and-baking soda mixtures. Most substances in a mixture can be separated out by physical means.