Classification of Chemicals!

In today's class we learned about the classification of chemicals. The homogeneous division of matter consists of only one visible component. The heterogeneous division of matter contains more than one visible component.

HOMOGENEOUS SUBSTANCES

PURE SUBSTANCES
Elements are substances that cannot be broken down into simpler substances by chemical reactions. Oxygen (O₂ ), iron, magnesium, and phosphorus (P₄) are all examples of elements. Compounds are substances that are made up of two or more elements (eg. water and sugar) and can be changed into elements (or other compounds) by chemical reactions. It is often very difficult to know if something is an element or a compound, because the differences are only visible on the atomic level. One method is to connect the substance to an electric current. This technique, called electrolysis, can split the compound apart.

Experiment of electrolysis performed in class:

HOMOGENEOUS MIXTURES
A solution is a homogeneous mixture of two substances. They usually involve liquids but don't have to (Fog, Steel). The component present in smaller amounts is the solute. In salt water, salt is the solute.

HETEROGENEOUS SUBSTANCES

Many mixtures are easy to identify while many others are easily confused as pure substances. In heterogeneous mixtures the different parts are clearly visible, while in homogeneous mixtures the different parts are not visible. Depending on the different types of mixtures, there are many methods that can be used to separate mixtures. We can do this with our hands (although time-consuming), or by the processes of filtration, distillation, crystallization and chromatography.

The process of filtration:

Only the precipitate is left behind.

Next class, measurement and chemistry!