Purity & mixtures: Elements compounds and mixtures: Chemistry: (9:1)

Pure substance

Either a single element or a single compound

Mixture

A combination of two or more substances that are not chemically combined

Formulation

A mixture that has been designed for a specific purpose

Melting/boiling point of pure substances

A single defined temperature

Melting/boiling points of mixtures

A range of temperatures

Melting point of pure water

0 °C

Boiling point of pure water

100 °C

Examples of formulations

Paint, processed food, fuels, cleaning products, cosmetics

Test for purity

Test melting/boiling point

Test if water is pure

Test if boiling point is exactly 100 °C

Solution

A mixture that forms when one substance dissolves another

Molecular formula

A chemical formula that shows the number and kinds of atoms in a molecule

Empirical formula

The lowest whole-number ratio of elements in a compound

Relative formula mass

The sum of the relative atomic masses of the elements as given in the formula