mass action rate law for third order forward, third order reverse, reversible reactions, two reactants mass action rate law for third order forward, third order reverse, reversible reactions, two reactants, one product, continuous scheme <n0:math xmlns:n0="http://www.w3.org/1998/Math/MathML"> <n2:semantics xmlns:n2="http://biomodels.net/SBO/" definitionURL="http://biomodels.net/SBO/#SBO:0000062"> <n2:lambda> <n2:bvar><n2:ci definitionURL="http://biomodels.net/SBO/#SBO:0000037">kf</n2:ci></n2:bvar> <n2:bvar><n2:ci definitionURL="http://biomodels.net/SBO/#SBO:0000040">kr</n2:ci></n2:bvar> <n2:bvar><n2:ci definitionURL="http://biomodels.net/SBO/#SBO:0000509">R1</n2:ci></n2:bvar> <n2:bvar><n2:ci definitionURL="http://biomodels.net/SBO/#SBO:0000509">R2</n2:ci></n2:bvar> <n2:bvar><n2:ci definitionURL="http://biomodels.net/SBO/#SBO:0000512">P</n2:ci></n2:bvar> <n2:apply> <n2:minus /> <n2:apply> <n2:times /> <n2:ci>kf</n2:ci> <n2:ci>R1</n2:ci> <n2:ci>R1</n2:ci> <n2:ci>R2</n2:ci> </n2:apply> <n2:apply> <n2:times /> <n2:ci>kr</n2:ci> <n2:ci>P</n2:ci> <n2:ci>P</n2:ci> <n2:ci>P</n2:ci> </n2:apply> </n2:apply> </n2:lambda> </n2:semantics> </n0:math> Reaction scheme where the products are created from the reactants and the change of a product quantity is proportional to the product of reactant activities. The reaction scheme does include a reverse process that creates the reactants from the products. The rate of the forward process is proportional to the quantity of one reactant and the square of quantity of the other reactant. The rate of the reverse process is proportional to the cube of one product quantity. It is to be used in a reaction modelled using a continuous framework.