Chemical word equations

 

What are chemical word equations?

A word equation is a way of writing a chemical reaction using the names of the substances that are involved. It shows what substances react together and what substances are formed as a result. Word equations are useful because they are simple and clear to understand and communicate, rather than writing a long description of the reaction.

 

Word equations also help us to record and share our work with others. For example, instead of writing this:

“When sodium and hydrochloric acid react, they produce sodium chloride and hydrogen.”

We can write a word equation like this:

sodium + hydrochloric acid → sodium chloride + hydrogen

 

What are the rules for writing word equations?

The rules for writing word equations are as follows:

 

• The names of the reactants are written first, separated by plus signs (+).
• An arrow (→) is used to show that a chemical reaction has occurred.
• The names of the products are written after the arrow, separated by plus signs (+).
• No words that describe the physical state or appearance of the substances, such as powder, solution or gas, are used in word equations.

 

How are chemical word equations different from chemical symbol equations?

Instead of using the names of the substances, chemical equations use the symbols and formulae of the elements and compounds that are involved in chemical reactions. For example, this is a chemical equation:

C + O2 → CO2

This equation uses the symbols of the elements carbon (C) and oxygen (O), which are found in the periodic table. It also uses the formula of the compound carbon dioxide (CO2), which shows how many atoms of each element are in one molecule.

A chemical word equation uses the names of the substances, but the order of the equation is similar to a chemical equation. For example, this is a chemical word equation for the same reaction:

carbon + oxygen → carbon dioxide

 

🧪 Knowledge Check: Chemical Word Equations

Test your understanding of how to write and name chemical reactions based on the lesson guide.

1. On which side of a chemical word equation are the reactants always written?

• The right-hand side
• The left-hand side
• Underneath the arrow

2. What is the correct name for the substance produced when magnesium reacts with oxygen?

• Oxygen magneside
• Magnesium oxygenate
• Magnesium oxide

3. In a word equation, what does the arrow specifically mean?

• The substances are equal
• React to form (or yield)
• The reaction is finished

4. When naming a compound that contains a metal, a non-metal, and oxygen, what should the non-metal's name end in?

• -ide
• -ate
• -ine

5. Which of the following is the correct word equation for the reaction between iron and sulfur?

• Iron + Sulfur → Iron sulfide
• Iron sulfide → Iron + Sulfur
• Iron + Sulfur = Iron sulfide

Click to Reveal Answers

1. The left-hand side (Reactants are starting substances written on the left).
2. Magnesium oxide (When a metal reacts with a non-metal, the ending changes to -ide).
3. React to form (or yield) (The arrow indicates the chemical change into new substances).
4. -ate (The -ate ending shows that oxygen is present in the compound).
5. Iron + Sulfur → Iron sulfide (Reactants on the left, arrow in the middle, and correctly named product on the right).

 

Summary:

 

• A chemical reaction can be described using the names of the substances that are involved in it. This is called a word equation.
• Word equations do not show any chemical symbols or formulae, only the names of the substances.
• In a word equation, the substances that react together are called reactants, and the substances that are formed are called products.
• A word equation has the format, reactants → products. A plus sign (+) is used to separate two or more reactants or products.