[sabah]

A calorimeter contains 25.0 ml of water at 12.5 C. When 1.80 g of X (a substance with a molar mass of 55.0 g/mol) is added, it dissolves via the reaction

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


and the temperature of the solution increases to 30.0 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*C and 1.00 g/ml ] and that no heat is lost to the calorimeter itself, nor to the surroundings.

Express your answer numerically in kilojoules per mole.

OK THIS IS HOW I DID THE QUESTION, HOWEVER ITS WRONG!!!!

dH solution/mole X = - (4.18 J/gC * 25.0 g H2O * (30.0-12.5)C / (1.80 g / 55.0 g/mole) = 55925 J/mol

[Astrokel]

They want it in kJ/mol and check your mass of solution.