So, let's look at how we would balance this equation.

Okay?

The first thing is, we want to write our equation, so that we have CH4, which is

the formula for methane, reacting with oxygen to form carbon dioxide and water.

Now, we've already seen what the rebalanced equation looks like, but

we're going to show the process by which we actually balance equations.

So, the first thing I want to do,

is I want to make a list of all the elements that I see in the reaction.

Note, that the elements on the left must be the same elements on the right.

And then I'm going to basically tally up how much I have of each atom.

So when I look at my equation, I look at the reactant side on, here on the left,

and I see that I have 1 carbon, I have 4 hydrogens, and I have 2 oxygens.

I do the same thing on the product side, where I have 1 carbon, I have 2 hydrogens,

and I have 3 oxygens, because I have 2 oxygens and 1 oxygen there.

Note that our subscripts, remember, tell us how many we have of

that particular element in a unit of that molecule.

So now, go back to my tally sheet at the bottom, and I notice that my carbon is

the same, which is great, but I notice that my Hydrogens are not.

I have 4 Hydrogen atoms on the left, and only 2 Hydrogen atoms on the right.

So I need to add a coefficient, so that I have the same number on both sides.

Now there's not any particular place that's the best place to start,

we can actually start with any of our elements.

I usually go in order from the, a, as the way I wrote them on my tally sheet, but

if you have trouble with one element, skip it and

come back to it after you've balanced the other elements.

So now, and for my hydrogen, I need to add a 2 in front of the H2O,

because that gives me 2 times 2, which is 4 hydrogens.

But note this, also change the number of oxygens, so now I have 2

oxygens in the water, but I also have 2 oxygens here in the carbon dioxide.

So, I now have a total of 4 oxygens.

So, while I fixed my hydrogens, I did not fix the oxygens, because now I

have 4 oxygens on the right side of the equation, and only 2 on the left.

So now, I need to go back and put a 2 in front of O2,

and when I do that, the only thing that changes is the number of oxygens, and

I see that I have 4 oxygens on the left, and 4 oxygens on the right.

Now note, that it's always a good idea to go back at the very end and

recheck everything.

I have 1 Carbon on the left,.

1 carbon on the right.

4 hydrogens on the left.

2 time 2, so 4 hydrogens on the right.

2 times 2, 4 oxygens on the left.

And I have 2 oxygens here, and 2 oxygens there for a total of 4.

So I see that all of my elements are balanced.

So now, I have a balanced chemical equation.