A substance that increases the rate of a chemical reaction, without being consumed or produced by the reaction. Catalysts speed both the forward and reverse reactions, without changing the position of equilibrium . Enzymes are catalysts for many biochemical reactions. Compare with anion . A cation is a positively charged ion.
Metals typically form cations.
Compare with physical change . A chemical change is a dissociation, recombination, or rearrangement of atoms. A compact notation for describing a chemical change. Coefficients are inserted before the formulas to ensure that the equation is balanced . The phase in which each substance is found is usually indicated in parentheses after each formula.