NH4NO3(s) right arrow NH4+(aq) + NO3−(aq)

Question

In order to measure the enthalpy change for this reaction, 1.21 g of NH4NO3 is dissolved in enough water to make 25.0 mL of solution. The initial temperature is 25.8°C and the final temperature (after the solid dissolves) is 22.0°C. Calculate the change in enthalpy for the reaction in kJ. (Use 1.0 g/mL as the density of the solution and 4.18 J/g · °C as the specific heat capacity.)

Answer 1

q = mass H2O x specific heat H2O x (Tfinal-Tinitial)
Then delta H/g = q/1.21 and
delta H/mol = (q/1.21) x molar mass NH4NO3. Convert to kJ.

Answer 2

how do I find the mass of H2O?

Answer 3

The problem tells you that the density of h2O is 1.0 g/mL.
mass = volume x density
mass = 25.0 mL x 1.0 g/mL = ? grams.