The Law of Mass Action (generally referred to as LOMA) states that for a balanced chemical reaction, the Rate of Reaction is directly proportional to the Molar Concentration of the reactant(s) raised to the power of their Coefficients. For example,
aA + bB ----------> cC + dD
R is directly proportional to [A]^a×[B]^b
R = K.([A]^a).([B]^b)
where K is the proportionality constant, generally known as the rate constant of the reaction.