1. Chemical Equations Learning Objective:
To write and explain chemical equations.

2. Chemical Equations Learning Outcomes
Good if you are able to interpret word equations.
Even better if you are able to use molecular models to represent reactions.
Great if you can write word equations and use as part of an explanation.
Out of this world if you can write balanced symbol equations.

3. WORD EQUATIONS REACTANTS PRODUCTS
Word equations are a short way of describing reactions
They are written in the format:
REACTANTS
PRODUCTS
The substances that react together
The substances that are made

4. WORD EQUATIONS magnesium + oxygen magnesium oxide example
When magnesium burns it reacts with the oxygen in the air to make magnesium oxide
Identify the reactants
Write them on the left hand side
Identify the products
Write them on the right hand side
magnesium + oxygen
magnesium oxide

5. WORD EQUATIONS sodium + chlorine sodium chloride example
White crystals of sodium chloride are formed when green chlorine gas is reacted with sodium metal.
Identify the reactants
Write them on the left hand side
Identify the products
Write them on the right hand side
sodium chlorine
sodium chloride
Use names only!

6. WORD EQUATIONS Common Mistakes sulphate zinc + copper
Zinc reacts with blue copper sulphate solution to form colourless zinc sulphate and copper
sulphate
zinc + copper
zinc sulphate + copper
use full name

7. WORD EQUATIONS calcium carbonate hydrochloric acid
Common Mistakes
When calcium carbonate is added to hydrochloric acid, the solution bubbles making calcium chloride, water and carbon dioxide
calcium carbonate + hydrochloric acid
water
calcium chloride + carbon dioxide
Reactants on left of arrow, all products on the right of the arrow
calcium chloride
carbon dioxide
calcium carbonate
hydrochloric acid + + +
water

8. However FORMULA EQUATIONS REACTANTS PRODUCTS
These equations use formula instead of names
The formula are often given to you
They are also written in the format:
REACTANTS
PRODUCTS
However
They need to be balanced.
There needs to be the same number of each type of atom on both sides of the equation

9. 2 Mg + O2 2 MgO FORMULA EQUATIONS
When magnesium burns it reacts with the oxygen in the air to make magnesium oxide 2
Mg + O2 2
MgO
Oxygen comes bonded to magnesium

10. 2 Na + H2O 2 2 NaOH + H2 FORMULA EQUATIONS
If sodium (Na) is added to water (H2O) sodium hydroxide (NaOH) and hydrogen gas (H2) are formed 2
Na + H2O 2 2
NaOH + H2
but a hydrogen comes joined to an oxygen and a hydrogen
Can get these from here
and get a sodium
need another hydrogen
need an oxygen and another hydrogen

11. Try These 2 2 3 2 3 Mg + O2 Zn + HCl Fe + Cl2 NaOH + HCl CH4 + O2
Mg O2
Zn HCl
Fe Cl2
NaOH HCl
CH O2
Ca H2O
NaOH H2SO4
CH3OH O2
MgO
ZnCl H2
FeCl3
NaCl H2O
CO H2O
Ca(OH) H2
Na2SO H2O 2