Question

How do you balance chemical reactions?

Answer 1

Balancing equations is simple;
You must balance the reactants (before the arrow) so they match the products and vice versa...

e.g.
SnO2 + H2 → Sn + H2O

Reactants
Sn = 1
O = 2
H = 2

Products
Sn = 1
H = 2
O = 1

To balance this particular equation you must change the products to match the reactants as O = 1 compared to 2 (due to the number in equation)

So you would put a 2 infront of H2O on the product side (used brackets to show - don't actually use when balancing)
SnO2 + H2 → Sn + [2]H2O

Reactants
Sn = 1
O = 2
H = 2

Products
Sn = 1
H = 4
O = 2

Now since H = 4 (2x2--> [2]H2O) on the product side you need it to equal 4 on the reactant side so you put a 2 infront of H2 on the side before the arrow
SnO2 + [2]H2 → Sn + [2]H2O

Reactants
Sn = 1
O = 2
H = 4

Products
Sn = 1
H = 4
O = 2

Now both sides are balanced..... :P send me a message with any specific examples

Answer 2

Just make sure both sides have equal no. of molecules of their respective elements.....go through this video you will get it very easily..... https://www.khanacademy.org/science/chemistry/chemical-reactions-stoichiometry/v/balancing-chemical-equations