Question

how do we balance equations??

Answer 1

the cantity of molecules of substances from the left part of equation need being equale with cantity of molecules of substances what are resulted from processe,so from the right part of equation

- so if the resultate not is in equilibrue you need to make it if you multiplie with necessary numbers the molecules from left part or the right part till will get the equilibrue of these two parts

Answer 2

go to greg thatcher.com theres a chemical equation balancer there

Answer 3

You just have to make sure that the sum of number of moles of elements is equal on both sides.

E.g.

Mg + O2 --> MgO

The ratio of O2 : O is 2 : 1 therefore it's not balanced. To balance it you have to add a 2 in front of MgO so O will have a ratio of 2.

Mg + O2 ---> 2MgO
However, the Mg is not balanced on bothsides so you have to add another 2 in front of the Mg reactant. So the entire equation will look like this.

2Mg + O2 ---> 2MgO

This is just a basic example, the chemical equations can get even more complicated than this.