[coupecnc]

Hey! I really need help balancing equations. I don't get it, at all... and have tried researching all night. Can someone PLEASE help me?!
thanks!

[jjwoodhull]

What is the equation that you need to balance? I can better explain it by example.

[Unknown008]

One of the simplest;

C + O2 -> CO2

no need to balance, since there are the same number of atoms on both sides. (note that this reaction represents the combustion of carbon)

A little more complicated;

Mg + HCl -> MgCl2 + H2

Now, if you count the number of atoms on the left hand side, there are:
1 Mg, 1 H and 1 Cl

And on the right hand side:
1 Mg, 2H and 2 Cl

See? They are not the same, thus the term unbalanced equation. By trial and error, put a number in front of a substance to balance the equation. Adding a '2' in front of Mg gives:

2Mg + HCl -> MgCl2 + H2

and, if you count the number of atoms on the left hand side, there are:
2 Mg, 1 H and 1 Cl

And on the right hand side:
1 Mg, 2H and 2 Cl

Not good, I increased the number of Mg, but it is the number of H and Cl which needs to be increased. So I'll retry, this time by putting a '2' in front of the HCl. (Note that the 2 will apply for both H and Cl)

Mg + 2HCl -> MgCl2 + H2

and, if you count the number of atoms on the left hand side, there are:
1 Mg, 2 H and 2 Cl

And on the right hand side:
1 Mg, 2H and 2 Cl

Now, it is good!! (note that it is the basic reaction of metal + acid)
~~~~~~~~~

And more complicated even!

Fe + O2 -> Fe2O3

(oxidation of iron)

Now we have 1 Fe and 2 O on the LHS (left hand side) and 2 Fe and 3 O on the RHS (right hand side)

Putting a '2' in front of the Fe gives

2Fe + O2 -> Fe2O3

There are the same number of Fe on both sides... BUT the number of O are not equal!!

If you put '2' in front of O2, you'll have

2Fe + 2O2 -> Fe2O3

but it is still not good! Since 4 O on LHS and 3 O on RHS.

The better is putting a 3 in front of O2 and 2 in front of Fe2O3, giving

2Fe + 3O2 -> 2Fe2O3

Now, the O are equal, but look and count! There are now more Fe on the RHS! Replace the 2 on the LHS by 4 to finally balance the equation correctly, giving

4Fe + 3O2 -> 2Fe2O3

Hope it helped! :)

Post back for any questions! ;)

[Unknown008]

Nice and clear explanation!

Thanks Cred! :)