Answer:

what is a pure substance?

A substance that has a fixed chemical composition throughout is called a pure substance.

• A mixture of two or more phases of a pure substance is still a pure substance

• as long as the chemical composition of all phases is the same

• (Fig. 3– 2). A mixture of ice and liquid water, for example, is a pure substance

• because both phases have the same chemical composition. A mixture

• of liquid air and gaseous air, however, is not a pure substance since the

• composition of liquid air is different from the composition of gaseous air,

• and thus the mixture is no longer chemically homogeneous. This is due

• to different components in air condensing at different temperatures at a

• specified pressure.