Question

4. A calorimeter contains 500 g of water at 25°C. You place a cold pack containing 100 g of crystalline ammonium nitrate inside the calorimeter. When the ammonium nitrate finishes dissolving, the temperature of the water inside the calorimeter is 9.3°C. The specific heat of water is 4.18 J/g–°C. What is the enthalpy of fusion (ΔHf) of the ammonium nitrate? (Show your work.) Where necessary, use q = mHf.

Answer 1

this one I definitely am confused on Dr B, i tried remembering but nothing

Answer 2

I'm curious. Do you mean delta H formation or delta H fusion or could you mean delta H solution

Answer 3

it would probably be fusion, right.... based on the rest of the question? since it's asking for specific heat

Answer 4

OK, so I'm guessing that you're guessing as to the meaning. If you want the delta H solution here is how to go about it.
q = mass H2O x specific heat H2O x (Tfinal-Tinitial)
q = 500 x 4.18 x (9.3-25) = -32,813 joules and that is the result 2ith 100 g NH4NO3. mols NH4NO3 = 100 g x (1 mol/80g) = 1.25
Then 32,813/1.25 = 26,250 or 26.2 kJ/mol.