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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.