Word equationsChemical Reactions – Year 8 Science

Word equationsChemists often use word equations as a way of quickly informing us what the reactants and products are in a reaction.

Reactants: a substance that takes part in and undergoes change during a reaction

Products: The products are the substances that are formed during the chemical change.

Structuring word equationsLike mathematical equations, chemical word equations are structured the same throughout the world (this is called a scientific convention).

- the names of the reactants are always on LEFT- an arrow (meaning “reacts to give”)- the names of the products are always on RIGHT

For example:

Magnesium + Copper Oxide Magnesium Oxide + Copper

Steel (Iron) Wool + Copper Sulphate Iron Sulphate + Copper

Identifying States of matterWhen writing worded equations, it will assist the reader if you can communicate the state of matter that the reactants and products are in.

To do this, the scientific convention is as follows:

A solid is identified by a subscript (s)A liquid is identified by a subscript (l)A gas is identified by a subscript (g)An aqueous solution (a substance dissolved in water) is identified by a subscript (aq)

You tryRe-write the following sentences as word equations:

- Magnesium burned brightly reacting with the oxygen in the air to form magnesium oxide.

- Hydrochloric acid reacted with the calcium hydroxide to give water and calcium chloride

- Hydrogen gas and oxygen gas combine to form water.

How did you go?Re-write the following sentences as word equations:

- Magnesium burned brightly reacting with the oxygen in the air to form magnesium oxide.

Magnesium + Oxygen Magnesium Oxide

- Hydrochloric acid reacted with the calcium hydroxide to give water and calcium chloride

Hydrochloric acid + Calcium Hydroxide Water + Calcium Chloride

- Hydrogen gas and oxygen gas combine to form water.

Hydrogen + Oxygen Water

Remember!Feel free to watch this video as many times as you like.

Pause, take notes, rewind if necessary.

Take note of any questions that you have – we will have time in class to discuss these at length.

In class, rather than taking notes, we will be practicing the skills covered in this video. We will do this individually, in small

groups, and as a whole class.

Optional ExtensionBalancing Equations:

Magnesium + Oxygen Magnesium Oxide

Mg(s) + O2 (g) MgO (s)

Harder:

Iron oxide(s) + carbon(s) iron(s) + carbon dioxide(g)

Fe2O3 + C Fe + CO2