What is a word equation?

A  word equation is  a simple way of representing a reaction using the names of the chemicals.

In a word equation reactants are transformed into products according to the following general equation

Reactants → Products


  • The reactants are the chemicals that react in a reaction.
  • The arrow sign means ‘give’ or ‘react to produce’
  • The products are the chemicals that are produced.

In a chemical reaction mass is always conserved. This is known as the "Law of Conservation of mass."

The following reaction cannot occur as mass is not conserved.

Sodium iodide + chlorine → Iodine

Reactants Products
Sodium ?
Iodine Iodine
Chlorine ?

Where did the sodium and the chlorine go? They must be included in the equation! Matter cannot just disappear or appear from no where.

The correct equation is

Sodium iodide + chlorine →Iodine + sodium chloride

Is this reaction matter is conserved. The elements that react break apart recombine to produce new substances.

Reactants Products
Sodium Sodium
Iodine Iodine
Chlorine Chlorine

Examples of other word equations include

  1. hydrogen + oxygen → water
  2. magnesium + oxygen → magnesium oxide
  3. carbon + oxygen → carbon dioxide
  4. hydrochloric acid + zinc → zinc chloride + hydrogen gas
  5. potassium iodide + lead nitrate → potassium nitrate + lead iodide