Homework Help: Chemistry

Posted by Abby on Thursday, June 21, 2012 at 9:00pm.

A calorimeter contains 30.0 mL of water at 11.0 degrees C. When 1.50 g of X (a substance with a molar mass of 65.0 g/mol) is added, it dissolves via the reaction:

X (s)+H2O (l) ---> X (aq)
and the temperature of the solution increases to 26.0 degrees 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.

I have been stuck on this question and have only 1 attempt left. I am unsure of the steps to get to the answer. Please explain?

Chemistry - DrBob222, Friday, June 22, 2012 at 12:26am
q = mass H2O x specific heat H2O x (Tfinal-Tinitial)

Then delta H = q/g = q/1.50g
delta H/mol = (q/1.50)* 65.0 = ? J/mol

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