1. Kaupapa: 01 / 06 Thursday Learn how to write chemical equations
Learn how to interpret chemical formulae

2. Do you remember?
What is the difference between a chemical change and a physical change?
What are the some things you can observe in chemical changes?
Define a chemical reaction

3. Do you remember? What is the symbol for this element?
What element does this symbol represent?

4. 1. Iron nail in copper sulfate solution

5. 2. Heating up sugar

6. 3. Heating up egg white

7. 4. Heating up a piece of chocolate

8. 5. Potassium iodide + Lead nitrate

9. 6. Magnesium + Hydrochloric acid

10. 7. Baking soda + Vinegar

11. Writing Chemical Equations and Interpreting Chemical Formulae

12. Chemical Equations
For every chemical reaction, you should be able to write chemical equations for it.
A typical chemical equation looks like this:

13. Question:
How is a chemical equation different from a mathematical equation?

14. Question:
How is a chemical equation different from a mathematical equation?
An arrow must be used instead of an equal sign.
There can be any number of reactants and products.
“+” sign does not necessarily mean “adding”. It could mean “and”.

15. Example 1: Iron in copper sulfate solution
When an iron nail is added to a beaker of copper sulfate solution, two new substances were formed – copper metal and iron sulfate solution.
Write a word equation.
Write a symbol equation.

16. Example 2: Magnesium in HCl
When a piece of magnesium is added to hydrochloric acid in a test tube, it produced magnesium hydroxide and hydrogen gas.
Write a word equation.
Write a symbol equation.

17. Example 3: Combustion of hydrogen gas
Hydrogen gas has been collected in a test tube and then brought to a flame. It reacted with oxygen in the air to produce water, with an audible “pop”.
Write a word equation.
Write a symbol equation.

18. Example 4: Burning magnesium
A small piece of magnesium metal was burnt in the air to produce white magnesium oxide powder.
Write a word equation.
Write a symbol equation.

19. Sodium Chloride (salt)
Chemical Formulae
Name
Chemical Formula
Water
Oxygen gas
Carbon dioxide
Sodium Chloride (salt)
Hydrochloric acid
Sulfuric acid
*Calcium hydroxide

20. Interpreting Formulae
Chemical Formula
Atomic Composition
H2O O2
CO2
NaCl
HCl
H2SO4
*Ca(OH)2

21. Are you up to the challenge?
Chemical Formula
Atomic Composition
NaHCO3
CH3COOH
Al(OH)3
Na2SO4
Ca(NO3)2
(NH4)2CO2
Al2(SO4)3

22. What have we learnt today?
NaOH
C3H7OH
Fe(OH)3