To learn to balance chemical equations by inspection. According to the law of conservation of mass, matter cannot be created or destroyed. Therefore, a chemical equation must show the same number of each kind of atom in the reactants as it does in the products. As shown in the figure, the balanced equation 3H_2 + N_2 rightarrow 2NH_3 has 6 atoms of hydrogen and 2 atoms of nitrogen on each side of the arrow. One is often presented with unbalanced chemical equations for which one must supply the coefficients. The following equation is not balanced: CaSO_4 + AlCl_3 rightarrow CaCl_2 + Al_2(SO_4)_3 Notice that “SO_4” appears in two different places in this chemical equation. SO^2-_4 is a polyatomic ion called “sulfate.” What number should be placed in front of CaSO_4 to give the same total number of sulfate ions on each side of the equation? ?CaSO_4 + AlCl_3 rightarrow CaCl_2 + Al_2 (SO_4)_3 Express your answer numerically as an integer.