A calorimeter contains 27.0 mL of water at 13.0, ^{circ}C. When 1.30 g of rm X (a substance with a molar mass of 81.0 g/mol) is added, it dissolves via the reaction
rm X{(s)}+H_2O{(l)} rightarrow X{(aq)} and the temperature of the solution increases to 28.0, ^{circ}C.
Calculate the enthalpy change, Delta H, for this reaction per mole of X.
Assume that the specific heat and density of the resulting solution are equal to those of water [4.18 J/g and 1.00 g/mL and that no heat is lost to the calorimeter itself, nor to the surroundings.