chemical changes word equations. chemical reactions – what to look for there may be a change of...

Chemical Changes Word equations

Chemical reactions – What to look for

• There may be a change of colour

Chemical reactions – What to look for

• There may be a gas given off (bubbles)

Chemical reactions – What to look for

• There may be an energy change (gets hotter or colder)

Chemical reactions – What to look for

• New substances are formed, and the change is usually difficult to reverse

Learning for today

1) Know the meanings of the words reactant, product and word equation

2) Be able to write word equations for chemical reactions

Physical?

OR

Chemical?

Physical or chemical – how can we tell?

Part 1 – Reactants and ProductsIf we made a cake we would start with the ingredients,

mix and cook them to give us a finished cake

The ingredients are the reactants, and the finished cake is the product.

Activity

Task:

1) Copy the table

2) Think of some

examples from the last

lesson, and from your

book, of reactants and

products

3) Fill in your table

Experiment Reactants Products

Baking a Cake

In a chemical reaction we start with one set of chemicals called

the reactants, a reaction happens and we end up with another

set, called the products.

Part 2 - Word Equations

To show what is happening during a chemical reaction we can write a word equation

Eggs + flour + milk + butter Cake

Word Equations

For this reaction the word equation is

Eggs + flour + milk + butter Cake

Copy this downWe use word equations to show what is happening in a chemical reaction. The reactants go on the left side and the products on the right. We use an arrow not an equals sign (=). The arrow means “reacts to form”

Your Turn…

When methane is burned in oxygen it

produces a gas, carbon dioxide and water.

1) What are the reactants?2) What the products?3) What is the word equation?

Your Turn…

When methane is burned in oxygen it

produces a gas, carbon dioxide and water.

1) What are the reactants?2) What the products?3) What is the word equation?

Methane + oxygen carbon dioxide + water

Task

Using the work card, work out what are the

reactants and products then complete the

word equations for the chemical reactions

How have you done?

1) Define and give examples of the words reactant and product and word equation

2) Give an example of a word equation for a chemical reaction that we did last lesson.