A 0.470-g sample of magnesium reacts with 200 g dilute HCl in a coffee-cup calorimeter to form MgCl₂(aq) and H₂(g). Th e temperature increases by 10.9 °C as the magnesium reacts. Assume that the mixture has the same specific heat as water and a mass of 200 g.

(a) Calculate the enthalpy change for the reaction. Is the process exothermic or endothermic?

(b) Write the chemical equation and evaluate ΔH.