In the reaction Na2S(aq) + 2 HCl(aq) 2 NaCl(aq) + HS(g) the resulting solution weighs less than the sum of the original solutions because: some of the products escaped as a gas the weights of solutions are not additive O the chloride ion is heavier than the sulfide ion O this reaction is an exception to the Law of Conservation of Mass O some of the iron gets changed to hydrogen