Tips that might help you
Balance Equations

There's a law in nature that says you can't create or destroy matter - only change it. So, when you run into a chemical formula that starts you off with one carbon and you end up with six, you know it can't be right. If you see an equation that doesn't work out, it's probably not balanced. Here's where you learn how to do that.

Stoicheometry, like geometry, is a kind of math. It balances formulas so that what you start with and what you end with (the reactants and products) balance. Truthfully, some equations take some trial and error, but if you know a couple shortcuts, it's not bad.

When you have a chemical equation to balance, here's how I recommend starting.
  1. First, pick out any unusual elements that are uncommon. The common ones you'll see are carbon, hydrogen and oxygen, so leave those for a moment. If it has a zinc or cesium or palladium, those are good places to start. For example in the equation:
    H2SO4 + NaOH ----> H2O + Na2SO4

    I would start with the sodium because it's an easy one to pick out. I would notice that there are two sodiums on one side of the equation and only one on the other. That means you have to double the other side. You can't change any of the little lower numbers though - you may only place numbers in front of the molecules. So you can't do this:
    BAD! ==> H2SO4 + Na2OH ----> H2O + Na2SO4

    But you can do this:
    GOOD! ==> H2SO4 + 2 NaOH ----> H2O + Na2SO4
    Honestly, the equation still isn't balanced, and you'll have to change a few more things, but that's the first step I would take. So, #1, start with unusual elements.

  2. The second thing I try is to find the carbons. Many equations have carbon in them, so that's a good thing to hunt down. They're usually easier to balance than hydrogens and oxygens.
    C6H12O6 + O2 ===> CO2 + H2O

    If you start with oxygens and hydrogens, you'll go nuts trying to get this thing to balance. The carbons make this more simple. With one on one side and six on the other, it becomes much easier.
    C6H12O6 + O2 ===> 6 CO2 + H2O

    Again, there's more work to be done, but this is where I'd start on this equation.

  3. Finally, after taking care of the weirdos and carbons, I'd finally tackle the hydrogens and oxygens. Do whichever is easiest first and hope that the other one falls into place. If it doesn't, ya go back to the drawing board and keep playing with the numbers.
Here's an equation and step-by-step instructions on what I'd do to balance it.
PROBLEM:
CaCl2 + AgNO3 ----> AgCl + Ca(NO3)2

First I start with the weirdos. Ag (silver) is a good start. There is one on each side, so for now let's ignore it. Ne next weirdo is Ca (calcium). Again, ther is one on each side. Nitrogen is next. There is one on the first side and two on the second. Drats - I'm gonna have to work. So my first step will be to double the nitrogens on the first side.
CaCl2 + 2 AgNO3 ----> AgCl + Ca(NO3)2

Immediately I can see that my silvers no longer balance. I'm going to have to double the silvers on the right side now.
CaCl2 + 2 AgNO3 ----> 2 AgCl + Ca(NO3)2

Now, as I check through all of the other parts of the equation, I find that it all balances. Yeay!
Let's try the one we started with.
H2SO4 + NaOH ----> H2O + Na2SO4

My first step would be to try the sodiums, so I'd double the sodium hydroxide on the left side.
H2SO4 + 2 NaOH ----> H2O + Na2SO4

Now the sodiums balance, and the sulfurs balance. The hydrogens don't though. When we count them we find four on the left and two on the right. That's easily taken care of.
H2SO4 + 2 NaOH ----> 2 H2O + Na2SO4

It balances!
Now for a challenge.
Al(OH)3 + H2SO4 ===> H2O + Al2(SO4)3

Ug. Let's start with the aluminum. One on the left and two on the right. Easy enough.
2 Al(OH)3 + H2SO4 ===> H2O + Al2(SO4)3

Now, if you notice, the SO4 thingies stay together as a group. Let's do those next. There is one on the left and three on the right. Hmmm... let's try:
2 Al(OH)3 + 3 H2SO4 ===> H2O + Al2(SO4)3

Now the SO4's balance, but we have a bunch of hydrogens without a home now. On the left-hand side of the equation, there are a total of twelve hydrogens, so we need to increase out water on the right.
2 Al(OH)3 + 3 H2SO4 ===>6 H2O + Al2(SO4)3

Finally we count up our oxygens and keep our fingers crossed. If it balances, woo hoo! If it doesn't, we keep experimenting until it does.
You can look elsewhere on the internet for more practice.