Composition of Mixtures
Classification of matter
- Matter is classified in pure substances and mixtures
- A pure substance is matter that has a fixed composition. They contain atoms, molecules or formula units of a single type
- Aluminum (Al), water (H2O) or hydrogen gas (H2), sodium chloride (NaCl) or calcium carbonate (CaCO3) are pure substances
- A mixture is matter whose composition is not fixed. Therefore, it contains two or more types of atoms, molecules or formula units
- The molecules or formula units that are part of a mixture are called components
- g. The air we breathe is a mixture in which the components are oxygen, nitrogen and small amounts of other gases
- g. Water and oil is a mixture between two liquids
Types of Mixtures
- Homogeneous mixtures have the same composition throughout
- The composition is uniform because the components are mixed uniformly in the space
- g. Air is an homogenous mixture
- Heterogeneous mixtures varies from one region of the mixture to another
- The composition is made from distinct regions because the components separate
- g. Water and oil is an heterogeneous mixture
Molecules in a pure substance and mixtures
A pure substance, an homogeneous mixture and a heterogeneous mixture at the molecular level
