Provide two ways you can determine if the Law of Conservation has been observed after a chemical reaction occurs.

2.50 mol nocl was placed in a 2.50 l reaction vessel at 400ºc. after equilibrium was established, it was found that 28% of the nocl had dissociated according to the equation 2nocl(g) picture 2no(g) + cl2(g). calculate the equilibrium constant, kc, for the reaction.