If your air conditioner is more than several years old, it may use the chloroflu
ID: 1067524 • Letter: I
Question
If your air conditioner is more than several years old, it may use the chlorofluorocarbon CCl2F2 as the heat transfer fluid. The normal boiling point of CCl2F2 is -29.8 degrees Celsius and the enthalpy of vaporization is 20.11 kJ/mol. The gas and the liquid have molar heat capacities of 117.2 J/mol *K and 72.3 J/mol*K, respectively. How much energy is evolved as heat when 23.3g of CCl2F2 is cooled from +37.0 degrees celsius to -48.0 degrees celsius? make sure answer is given in the unit (J) and please make sure answer is the proper number of significant figures.
Explanation / Answer
heat released(q) =
enthalpy of vaporization (DHvap) = 20.11 kJ/mol.
normal boiling point of CCl2F2 = -29.8 degrees Celsius
gas and the liquid have molar heat capacities of 117.2 J/mol *K and 72.3 J/mol*K, respectively
no of mole of CCl2F2 cooled = w/mwt = 23.3/120.91 = 0.193 mole
q = ngas*Cm*DT1 + n*DHvap + nliquid*Cliquid*DT2
DT1 = 37 - (-29.8) = 66.8
DT2 = (-29.8 - (-48)) = 18.2
q = 0.193*72.3*66.8+ 0.193*20.11*10^3+0.193*117.2*18.2
= 5225.03 joule