#### Answer

24.075 kJ/mol

#### Work Step by Step

There are 60g of water in the calorimeter and the temperature drops from 22 to 16.9C. First we find the $\Delta T$ in degrees C, which is the same as K. To do so we have: $\Delta T = 22 - 16.9 = 5.1 K $. To ind the heat released we use the specific heat of water, which is 4.18 J/g*K.
Then we have:
4.18 J/g*K * 60g * 5.1K = 1279.08 J
We then convert this to kJ as follows:
1.279 kJ
To find the value of $\Delta H$ in kJ/mol we need to convert the 4.25g to moles of NH4NO3. We need to find the molar mass of NH4NO3 as follows:
N is 14g/mol
H is 1g/mol so 4*1 = 4
N is 14g/mol
O is 16 g/mol, 3*16 = 48
14 + 4 + 14 + 48 = 80g/mol
Therefore, 4.25g would be 4.25g * (1mol/80g) = 0.053 mol.
Then we take the 1.279kJ and divide by the 0.053mol and we get 1.279kJ/ 0.053mol = 24.075 kJ/mol