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Lesson 14 of 19

A change written in words

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5 min

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A chemical change can be written as one line of words. This line is a word equation.

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The idea

Magnesium oxide is magnesium joined with oxygen.

The starting substances go on one side: magnesium and oxygen.
Step 1 of 4
  1. The starting substances go on one side: magnesium and oxygen.
  2. The arrow means "makes".
  3. What the change makes goes on the other side.
  4. Magnesium oxide is a new substance.
Four changes as word equations
ChangeWord equation
Burning magnesiummagnesium + oxygen → magnesium oxide + heat + light
Rustingiron + oxygen + water → rust
Lime water and carbon dioxidelime water + carbon dioxide → calcium carbonate + water
Vinegar and baking sodavinegar + baking soda → carbon dioxide + water + sodium acetate

In a word equation, the starting substances are on the left. The new substances are on the right.

Heat and light are given out. They are not substances.

Rust is an iron oxide. It is a new, brown substance.

Try the lab to finish this lesson.