Bomb Calorimetry: Solving for Heat of Dissolution in NH4NO3

[viper2308]

Need help! I tried using the equation: Heat evolved= (specific heat)(Mass of Solution)(Change in Temp) but I cannot get the right answer.

In a coffee-cup calorimeter, 1.30 g of NH4NO3 is mixed with 75.0 g of water at an initial temperature of 25.00°C. After dissolution of the salt, the final temperature of the calorimeter contents is 23.19°C. Assuming the solution has a heat capacity of 4.18 J/°C·g and assuming no heat loss to the calorimeter, calculate the enthalpy change for the dissolution of NH4NO3 in units of kJ/mol.

 

[Bystander]

((1.3+75)x4.18x1.81x0.001)kJ / (1.30/80)mol = 35.5 kJ/mol