A calorimeter contains 17.0 mL of water at 11.0 °C. When 2.00 g of X (a substance with a molar mass of 58.0 g/mol) is added, it dissolves via the reaction

X(s) + H2O(1)->X(aq)

and the temperature of the solution increases to 28.0 °C.

Calculate the enthalpy change, AH, for this reaction per mole of X.

Assume that the specific heat of the resulting solution is equal to that of water [4.18 J/(g. °C)], that density of water is 1.00 g/mL, and that no heat is lost to the calorimeter itself, nor to the surroundings.

Express the change in enthalpy in kilojoules per mole to three significant figures.