Question

How would you balance this equation: `?H_3PO_4 + ?Mg(OH)_2 -> ? Mg_3(PO_4)_2 + ? H_2O`?

Answer 1

`2 H_3PO_4 + 3 Mg(OH)_2 -> Mg_3(PO_4)_2 + 6 H_2O`

Explanation:

To do it, I took the following steps :

• Balance Mg:

I have 3 Mg in `Mg_3(PO_4)_2` so I added 3 on the other side `3 Mg(OH)_2`

• Balance P :

Again I have 2 P in `Mg_3(PO_4)_2` so I added 2 on the other side `2 H_3PO_4`

• Balance H :

I have 6 H in `2 H_3PO_4` `(2xx3)` and 6 H in `3 Mg(OH)_2` a total of 12 H so I added 6 next to `H_2O`
`6 H_2O`

Notice that the O is automatically balanced : 8 O in `2 H_3PO_4` + 6 O in `3 Mg(OH)_2` = 8 O in `Mg_3(PO_4)_2` + 6 O in `6 H_2O`

I hope that was clear