A calorimeter contains 18.0 mL of water at 12.0, ^{circ}C. When 1.50 g of rm X (a substance with a molar mass of 43.0 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 30.0, ^{circ}C.
Calculate the enthalpy change, Delta H, for this reaction per mole of rm X.