How do you balance these equations?

H_3PO_4 (aq) + Mg(OH)_2(aq) -> Mg_3(PO_4)_2(aq) + H_2O(l)
C_4H_10(g) + O_2 (g) -> CO_2 (g) + H_2O(g)

1 Answer
Dec 3, 2016

The same way you balance all equations: conserve mass and charge.

Explanation:

H_3PO_4(aq) + Mg(OH)_2(aq) rarr MgHPO_4(aq) + 2H_2O(l)

C_4H_10(g) + 13/2O_2(g) rarr 4CO_2(g) + 5H_2O(g)

We have thus stoichiometrically balanced an acid-base, and a combustion reaction. "Garbage in equals garbage out."

If you like you can double the combustion reaction to remove the non-stoichiometric coefficient in the combustion reaction:

2C_4H_10(g) + 13O_2(g) rarr 8CO_2(g) + 10H_2O(g)

I prefer the former reaction inasmuch as it is easier to specify equivalent masses of hydrocarbon and dioxygen.