What’s the easiest way to balance equations in chemistry?

Honestly? Try putting the elements on each side of the reaction and count how many you have and how many you need to balance it for example:

CH4 + O2 => H2O+ CO2

Reactants:
1 C
4 H
2 O

Products:
1 C
2 H
3 O

So basically what you do now...you see that you have one carbon on each side but 4 hydrogen on recatants side and 2 hydrogen on the products side, so you need to multiply the water molecule by 2 to get the 4 hydrogens. Now because you multiplied (put coefficient 2 in front of it) the oxygen in h20 is now 2 oxygens right? So now you have 4 oxygens on the product side and 2 on the reactant side so in the reactant side, y più multiply it by 2 to get 4 oxygens.

The gas would begin to expand, and eventually the can would burst or explode.