Question

A coffee-cup calorimeter initially contains 125 g water at 24.2 degrees celsius. Ammonium Nitrate (10.5 g), also at 24.2 degree celsius, is added to the water, and after the ammonium nitrate dissolves, the final temperature is 18.3 degrees celsius.What is the heat of solution of ammonium nitrate in kj/mol? Assume that the specific heat capacity of the solution is 4.18 J/Cg and that no heat is transferred to the surrounds or to the calorimeter.

Answer 1

total gm of soution = 125 + 10.5 = 135.5 gm

T = 24.2 - 18.3 = 5.9⁰C

q = mass of solution specific heat of T

= 135.5 4.18 5.9

q = 3341.701 J = 3.3417 KJ

molar mass of ammonium nitrate = 80.043 gm/mol

then 10 .5 gm of ammonium nitrate = 10.5/80.043 = 0.1311 mole

0.1311 mole of ammonium nitrate have heat of solution 3.3417 KJ then 1 mole of ammonium nitrate have heat of solution = 1 3.3417 / 0.1311 = 25.4897 KJ

Heat of solution of ammonium nitrate is = 25.4897 KJ/mol