The reaction of solid calcium carbonate with hydrochloric acid is a heterogeneous reaction (a solid with a liquid). The rate law for this reaction will have the following form: rate = k[HCL]n. Explain why the concentration of calcium carbonate does not appear in the rate law.

The concentration of calcium carbonate does not appear in the rate law because it is a solid and its concentration is constant. The molar density, which is fixed, is the concentration of the solid. In this chemical reaction, only the amount of hydrochloric acid affects the rate of reaction.