In this example problem, we balance a chemical reaction which contains all ionic compounds by balancing the ions on each side. Our problem reads, "Aqueous aluminum nitrate reacts with aqueous ammonium phosphate to produce solid aluminum phosphate and aqueous ammonium nitrate. Write a balanced chemical equation for the reaction. We can start by writing out the reactants and products in an unbalanced reaction. Since all of these reactions and products are ionic compounds and the ions don't change, we can just balance the ions instead of individual atoms. We want to balance Al3+, nitrate, ammonium, and phosphate ions. Since each ion only shows up in one compound on each side, we can balance them in any order. I'll start with Al3+. Right now we have one aluminum ion on each side, so we can put a 1 coefficient in front of aluminum nitrate and aluminum phosphate. Now we have 3 nitrate on the left. To get 3 on the right, we can add a 3 coefficient in front of ammonium nitrate. And now we have three ammonium on the right. To get 3 ammonium on the left, we add a 1 coefficient in front of ammonium phosphate. And we have 1 phosphate ion on each side. We don't have any fractions so our coefficients should be 1, 1, 1, and 3. We don't write the 1 coefficients in the balanced chemical reaction, so the balanced chemical reaction would just be written like this.