Chemical equation to balance!! Can anyone do this for me?

Question

The chemical equation in words is:
perchloric acid (HClO4) (aq) + tetraphosphorus decaoxide (s) yeilds phosphoric acid (aq) + dichlorine heptaoxide (g),

I think that it is this before it is balanced....( the underscores are used to show that the number between is a subscript.)

HClO_4_ +P_3_O_10_ yeilds H_3_PO_4_+ Cl_2_O_7_

Answer 1

Unbalanced:

HClO4 + P4O10 -> H3PO4 + Cl2O7

Balance H:

3HClO4 + P4O10 -> H3PO4 + Cl2O7 (3 H atoms per side)

Balance Cl:

6HClO4 + P4O10 -> 2H3PO4 + 3Cl2O7 (6 Cl atoms per side)

Balance P:

12HClO4 + P4O10 -> 4H3PO4 + 6Cl2O7 (4 P atoms per side)

There are now 58 O atoms per side, so the equation is balanced.

Answer 2

Write it correctly and don't worry about underscores.
HClO4 + P4O10 -> H3PO4 + Cl2O7
First, if you have P4, you need to have 4H3PO4 on the other side, which means 12 HClO4 to balance the hydrogens. Then"
12 HClO4 + P4O10 -> 4H3PO4 + 6Cl2O7
This appears to be balanced. TaDa!!