Question

How do you balance SO2+O2+H2O=H2SO4?

Answer 1

`2SO_2 + O_2 + 2H_2O -> 2H_2SO_4`

Explanation:

Start with the skeleton equation:
`SO_2 + O_2 + H_2O -> H_2SO_4`

Atoms on the left: `1-S, 5-O, 2-H`
Atoms on the right: `1-S, 4-O, 2-H`

To make the number of oxygen on the left to be even, add `2` molecules to `H_2O` and a `2` to the right.

`SO_2 + O_2 + 2H_2O -> 2H_2SO_4`

Atoms on the left: `1-S, 6-O, 4-H`
Atoms on the right: `2-S, 8-O, 4-H`

To make the number of `S` to be the same, add `2` molecules to the `SO_2` on the left:

`2SO_2 + O_2 + 2H_2O -> 2H_2SO_4`

Atoms on the left: `2-S, 8-O, 4-H`
Atoms on the right: `2-S, 8-O, 4-H`

Balanced!