Balancing Chemical EquationsBalancing Chemical Equations

Just follow these steps…….Just follow these steps…….

It’s quite easy reallyIt’s quite easy really

Firstly you need an equation with the correct “formulae” in………. You’ll probably be given this in the question

Just like this one

Mg + O2 MgO

Mg

O

Then all you do is list the atoms that are involved on each side of the arrow

Mg + O2 MgO

[1] Just count up the atoms on each side

Then start balancing:

Mg + O2 MgOMg

O

1

1

1

2

[2] The numbers aren’t balanced so then add “BIG” numbers to make up for any shortages

And adjust totals

Mg + O2 MgOMg

O

1

1

1

2

2

2

2

Mg + O2 MgOMg

O

1

2

2

2

2

But the numbers still aren’t equal, so add another “BIG” number

2

And adjust totals again

NOW BOTH SIDES HAVE EQUAL NUMBERS OF ATOMS

WE SAY THAT THE EQUATION IS BALANCED!!

2

Try to balance these equations using the same method:

[1] Na + Cl2 NaCl

[2] CH4 + O2 CO2 + H2O

[4] Al + O2 Al2O3

[3] Li + HNO3 LiNO3 + H2

How did you get on??

[1] 2 Na + Cl2 2 NaCl

[2] CH4 + 2 O2 CO2 + 2 H2O

[4] 4 Al + 3 O2 2 Al2O3

[3] 2 Li + 2 HNO3 2 LiNO3 + H2

Here are the answers:

HOPE YOU’VE GOT THE IDEA… HOPE YOU’VE GOT THE IDEA… REMEMBER TO CHECK THAT REMEMBER TO CHECK THAT YOU CAN DO ELECTROLYSIS YOU CAN DO ELECTROLYSIS

EQUATIONS TOOEQUATIONS TOO

Electrolysis equations ones to check

[a] Cu2+ + e- Cu

[b] Cl- - e- Cl2

[c] H+ + e- H2

[d] Br - Br2 + e-

The answers are….

Remember to balance the charges on each side of the arrow

[a] Cu2+ + 2 e- Cu

[b] 2 Cl- - 2 e- Cl2

[c] 2 H+ + 2 e- H2

[d] 2 Br - Br2 + 2 e-

Hope that makes things a bit clearer….

Just remember it’s all about balance