This is difficult partly because life is a process, not a pure substance.

Even a number of pure substances (not mixtures) do this.

Most often, the solvent is a liquid, which can be a pure substance or a mixture.

All matter can be classified as either a "pure substance" or a "mixture".

A pure substance is something that you cannot separate with a physical change.

Only a chemical change will separate the pure substance, water, into its component elements.

Since milk is a mixture and not a pure substance, what might the chemical reaction be?

Air is often seen as a universal power or pure substance.

The usual way is to add other material to the pure substance.

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