Sodium carbonate reacts with hydrochloric acid in an exothermic reaction. The equation for the reaction is: Na2CO3(s) 2 HCl(aq) → 2 NaCl(aq) CO2(g) H2O(l) A student investigated the effect of changing the mass of sodium carbonate powder on the highest temperature reached by the reaction mixture. (a) Plan a method to investigate the effect of changing the mass of sodium carbonate powder on the highest temperature reached.