Two compounds (A and B) react to form compound C. The rate at which C is produced (in kg/hr) is proportional to the product of the masses of A and B present in the vessel. The stoichiometric relationship is: A+B C (in moles) The molar mass of A is twice that for B. When 10 kg of A and 20 kg of B were introduced into a batch reactor vessel, 6 kg of C were produced in 20 min. Obtain an expression for the mass of C in the reactor as a function of time.