How to calculate the molar heat of a solution and a heat of a solution
The calorimeter is prepared with 44.96 g of water, both at 22.6 Celsius. 2.42 g of salt are
dissolved in the water ( note the total solution mass) and the temperature falls to 19.9
Celsius . Calculate the heat of the solution for the salt. If the salt is potassium chloride,
calculate the molar heat of solution.
1. Finding the heat of solution for the salt:
water:
m = 44.96 g
T initial= 22.6 Celsius
T final= 19.9 Celsius
Salt:
m= 2.42 g
T initial= 22.6
T final= 19.9 Celsius
delta T = 2.7 Celsius
C = 4.184 J/ g Celsius
delta Q = mC delta T
= (44.96 g) ( 4.184 J/g celcius) ( 2.7 celcius)
= 507. 90 J
2. Finding the molar heat of the solution: ( really not sure about this)
m = 44.96 g
MW = 74.55 g/mol
mol = m/MW
= 44.96 g / 74.55 g/mol
= 0.603 mol
Molar heat: heat/mol
507. 90 J /0.603 mol
= 842.3 J/mol
=842.3 x 10 -3 KJ/mol