In: Chemistry
I'm trying to figure out the enthalpy of fusion, then compare it to the enthalpy fusion of ice, for an experiment that I did in a class the other day. It's really confusing me! The process involved placing ice into a calorimeter with room temperature water inside of it, then recording the change in temperature over a period of time. Thanks for the help.
Calorimeter mass = 7.96g
Calorimeter sp.heatcapacity = 3.3J/gK
Calorimeter temp change = (21.2C - 13.1C)
Ice mass - 9.58g
Water mass - 97.90g
Water temp change = (21.2C-13.1C)
Heat released by calorimeter : Mass of Calorimeter * Specific heat capacity of Calorimeter * Temperature change = 7.96 g * ( 3.3 J/ g K) * ( 21.2- 13.1) K = 212.8 J
Heat released by room temperature water : Mass of Calorimeter * Specific heat capacity of water * Temperature change = 97.90 g * ( 4.18 J/ g C) * ( 21.2- 13.1) C = 3314.7 J
Total heat released : 212.8 + 3314.7 J = 3527.5 J
Heat gained by ice = heat gained for melting of ice + heat gained by water for the increase in temperature
Heat gained by melting for ice : enthalpy of fusion ( H J/g) * mass = H * 9.58 J
heat gained by water for the increase in temperature = 9.58 g * 4.18 J/ g 0C * ( 13.1 - 0 ) 0C = 524.6 J
So, total heat gained : 9.58 H + 524.6
At thermal equilibrium, 9.58 H + 524.6 = 3527.5
Or, H = ( 3527.6 -524.5) / 9.58 = 313.5
The enthalpy of fusion of ice is: 313.5 J/ g = 313.5 * 18 J / mole = 5643 J/ mole = 5.643 kJ/ mole
(Molar mass of ice = 18 g/ mole)
The actual value of enthalpy of fusion of ice is 6.01 kJ/ mole