The fact that the number of each type of atom on each side is equal is related to the Law of Conservation of Mass. Balance this equation using the smallest possible integers, S + HNO3 H2SO4 + NO2 + H2O. What is the coefficient of the water? K2O + H2O What is the mass of 2.10 x 1021 atoms of copper, Cu? What is the molar mass of aspirin, C9H8O4?