# Working with enthalpy change for dissolution

In a coffee-cup calorimeter, 1.10 g of NH4NO3 is mixed with 76.0 g of water at an initial temperature of 25.00Â°C. After dissolution of the salt, the final temperature of the calorimeter contents is 23.93Â°C. Assuming the solution has a heat capacity of 4.18 J/Â°C Â· g and assuming no heat loss to the calorimeter, calculate the enthalpy change for the dissolution of NH4NO3 in units of kJ/mol.

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#### Solution Preview

We have heat evolved in the reaction as,

q = m x c x dT

here, m = 1.10 + 76 = 77.1 g

c = 4.08 J/C g

dT = T final - Tinitial = 23.93 - 25 = - 1.07 C

Therefore, q = -77.1 * 4.08 * 1.07 = -336.59 J

That is after dissolution heat is ...

#### Solution Summary

The solution gives not only the answers but also the steps required to arrive at the answer. No mathematical step was avoided in the derivation.