Chemical Reactions

A balanced equation

Notice that both sides of the arrow have the

same numbers of elements

Law of Conservation of Mass

in a chemical reaction, the total mass of the reactants is the same as the total mass of the products

Antoine Laurent Lavoisier1743-1794

Law of Constant proportions

in chemical compounds, the ratio of the elements is always the same

Joseph Proust 1754-1826

ReactantReactants are any chemicals that you start with.

Reactants and Products

ProductProducts are the chemicals that are made in the reaction.

In our example:

Hydrogen and Oxygen are the

reactants Water is the product

“While some reactions happen spontaneously when reactants are mixed, others will require a

catalyst.

An example of a catalyst is the application of heat to the reactants.

The catalyst is written over the top of the arrow in the equation as drawn below: