A system is said to be in dynamic equilibrium when: A system is said to be in dynamic equilibrium when: the sum of the concentrations of the reactants is equal to the sum of the concentrations of the products. you have let the reaction proceed for approximately 30 minutes and can assume there will be no more changes. there is no longer any net change in the concentrations of products or reactants. the forward and reverse reactions come to a halt. none of the above