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, two products, continuous scheme 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 quantity of one product and the square of the quantity of the other product. It is to be used in a reaction modelled using a continuous framework. <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">P1</n2:ci></n2:bvar> <n2:bvar><n2:ci definitionURL="http://biomodels.net/SBO/#SBO:0000512">P2</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>P1</n2:ci> <n2:ci>P1</n2:ci> <n2:ci>P2</n2:ci> </n2:apply> </n2:apply> </n2:lambda> </n2:semantics> </n0:math>