How do you balance #P_4 + O_2 -> 2P_2O_3#?
Count the number of atoms on each side to make sure they have the same number of atoms.
On the left side (or left of arrow),
P = 1
O = 1
On the right side
P = 2
O = 2
P is balanced but O isn't.
Find the lowest common multiple (LCM) of number of atoms present in O.
The LCM between 2 and 6 is 6.
On the left hand side, we need to make the number of atoms of O from 2 to become 6 by multiplying 3.
So insert a 3 in front of
Check your equation now:
Now double check to make sure the number of atoms are same on both side. - IMPORTANT
P = 4 atoms on left side and 4 atoms on right side - BALANCED
O = 6 atoms on left side and 6 atoms on right side - BALANCED
If they're all balanced, you're good to go write your balanced equation.
Overall, your balanced equation should look like: