1. Balancing Equations To be able to balance equations
Tuesday, January 01, 2019
Balancing Equations
To be able to balance equations

2. Symbols
Remember, each element has its own symbol(s) - all found in the periodic table
Every symbol begins with a capital, and may have one or more other non-capital letters which follow
E.g.
Oxygen = O
Nitrogen = N
Sodium = Na
Magnesium = Mg
Copper = Cu

3. magnesium + oxygen → magnesium oxide
Balancing
A chemical reaction can be described by the process
reactants → products
E.g. magnesium reacts with oxygen, producing magnesium oxide
magnesium + oxygen → magnesium oxide
2Mg + O2 → 2MgO

4. Balancing It is key you know how to balance the equations!
Remember: there must always be the same number of atoms on both sides
Numbers can only be put in front of the formula when it is needed

5. magnesium + oxygen → magnesium oxide
Look at the following reaction
magnesium + oxygen → magnesium oxide
2Mg + O2 → MgO
You’ll notice, that there are more green and blue circles on the left hand side, than there are on the right
To balance this, we can add a number in front of the right hand side
2Mg + O2 → 2MgO

6. hydrogen + oxygen → water
Look at the following reaction
hydrogen + oxygen → water
H2 + O2 → H2O
Again there is a problem – this time we have an oxygen atom missing from the right hand side
To balance this, we can add a number in front of the right hand side
H2 + O2 → 2H2O

7. hydrogen + oxygen → water
But this is still unbalanced!
hydrogen + oxygen → water
H2 + O2 → 2H2O
Finally, we can add a number in front of the hydrogen on the left hand side, to balance this up
2H2 + O2 → 2H2O

8. Example Look at the following reaction: H2SO4 + NaOH → Na2SO4 + H2O
The formulas are correct, but the number of atoms on the left are different from those on the right
Remember: we can only put numbers in front of the symbols…

9. Balancing H2SO4 + NaOH → Na2SO4 + H20
In the equation, there are more H atoms on the left, than there are on the right
So we can add a 2 in front of the H2O on the right side
H2SO4 + NaOH → Na2SO4 + 2H20
Now we have too many H and O atoms on the right hand side, so we can put a 2 in front of the NaOH on the left side
H2SO4 + 2NaOH → Na2SO4 + 2H20
Now everything balances!
Left hand side = 4 x H; 1 x S; 6 x O; 2 x Na
Right hand side = 4 x H; 1 x S; 6 x O; 2 x Na

10. Questions Write a word equation for what happens when copper burns
How many reactants are there in this reaction?
What are these reactants?
What is the product of the reaction?
When you find the mass at the end of the experiment, what chemical are you finding the mass of?
Answers
copper + oxygen → copper oxide
2 Reactants
Reactants: copper + oxygen
Product: copper oxide
You are calculating the mass of the copper oxide

11. CaCl2 + AgNO3 → AgCl + Ca(NO3)2
Balance The Equations
H2 + O2 → H2O
H2 + N2 → NH3
C3H8 + O2 → CO2 + H2O
Al + CuO → Al2O3 + Cu
K2O + H2O → KOH
CaCl2 + AgNO3 → AgCl + Ca(NO3)2

12. CaCl2 + 2AgNO3 → 2AgCl + Ca(NO3)2
Balance The Equations
2H2 + O2 → 2H2O
3H2 + N2 → 2NH3
C3H8 + 5O2 → 3CO2 + 4H2O
2Al + 3CuO → Al2O3 + 3Cu
K2O + H2O → 2KOH
CaCl2 + 2AgNO3 → 2AgCl + Ca(NO3)2