If I have the equation: X(aq) + H2O (l) <-> Y(aq) + Z(aq), is the rate equation Rate = k[X] or is it Rate = k[X][H2O]? I think it's Rate = k[X] but in TBR Kinetics Passage 7, Questions 46 and 47, they put [H2O] into the equation..
Not true. You ignore liquids IF their concentration is not changing. We don't know whether or not that is the case here. It would depend on whether or not there was a lot of water on the reactant side starting out. And even if you do leave it out, the reaction would still be a second order, pseudo first order reaction.