balanced equations NH4NO3

I see no equation there, but the molecular formula of the compound ammonium nitrate... :rolleyes:

The key to balance equations is to make sure there are equal number of atoms of an element on either sides of the arrow in a reaction. Putting a number in front of a formula means that every number of atoms in that compound is multiplied by the number you put in front.

For example:

NaOH + HCl \rightarrow NaCl + H_2O

You have 1 Na on both sides;
1 O on both sides
2 H on both sides
1 Cl on both sides.

The equation is balanced.

Fe_2O_3 + HCl \rightarrow FeCl_3 + H_2O

2 Fe on the left, one on the right. Not good
3 O on the left, one on the right. Not good
1 H on the left, 2 on the right. Not good
1 Cl on the left, 3 on the right. Not good.

But, balancing:

Fe_2O_3 + 6HCl \rightarrow 2FeCl_3 + 3H_2O

You'll see that there are the same number of atoms of an element on both sides!

I started by thinking:
2 Fe on the left, I need therefore 2 Fe on the right. So, I put 2 there.
That means I also have now (2x3) 6 Cl on the right. Putting 6 in front of HCl makes the Cl the same.
Now, I have 3 O and 6 H on the left, and 1 O and 2 H on the right. Putting 3 in front of H2O makes the atoms equal in number!