Chlorofluocarbon was once used in air conditiones as the heat transfer liquid its normal boiling point is -30 degrees C and its enthalpy of vaporization is 16J/g. The gas and the liquid have specific heat capacities of 0.61 J/g8C and 0.97 J/g*C, respectively. How much thermal energy is evolved when 10.0 g CCL2F2 is cooled from 40 degrees celsius to -40 degrees celsius

I will save myself a lot of work and let you do most of it but here is how to go about it. First, identify any phase changes (solid to liquid or liquid to gas).

q at any phase change = mass x heat vaporization (if vapor to liquid or liquid to vapor) or heat fusion (if liquid to solid or solid to liquid).
Between phase changes it is
q = mass x specific heat in that phase x (Tfinal-Tinitial).
Then add all of the qs together for the total.

To calculate the amount of thermal energy evolved when chilling 10.0 g of CCl2F2 from 40°C to -40°C, we need to consider several factors: the energy required to lower the temperature of the liquid from 40°C to its boiling point, the energy required for the phase change from liquid to gas, and the energy required to lower the temperature of the gas from its boiling point to -40°C.

Step 1: Energy required to lower the temperature of the liquid
To determine this, we will use the equation:
q = m * C * ΔT
where:
q is the thermal energy (in Joules)
m is the mass of CCl2F2 (10.0 g)
C is the specific heat capacity of the liquid (0.97 J/g°C)
ΔT is the temperature change (from 40°C to the boiling point of CCl2F2, which is -30°C)

q1 = 10.0 g * 0.97 J/g°C * (-30°C - 40°C)
q1 = 10.0 g * 0.97 J/g°C * (-70°C)
q1 = -679 J

Note: The negative sign indicates that energy is being removed from the system (exothermic process).

Step 2: Energy required for phase change (from liquid to gas)
To calculate this, we will use the equation:
q = m * ΔHvap
where:
q is the thermal energy (in Joules)
m is the mass of CCl2F2 (10.0 g)
ΔHvap is the enthalpy of vaporization (16 J/g)

q2 = 10.0 g * 16 J/g
q2 = 160 J

Step 3: Energy required to lower the temperature of the gas
To determine this, we will use the equation:
q = m * C * ΔT
where:
q is the thermal energy (in Joules)
m is the mass of CCl2F2 (10.0 g)
C is the specific heat capacity of the gas (0.61 J/g°C)
ΔT is the temperature change (from the boiling point of CCl2F2, which is -30°C, to -40°C)

q3 = 10.0 g * 0.61 J/g°C * (-40°C - (-30°C))
q3 = 10.0 g * 0.61 J/g°C * (-10°C)
q3 = -61 J

Step 4: Total thermal energy evolved
To calculate the total thermal energy evolved, add together the energies obtained in steps 1, 2, and 3:

Total energy = q1 + q2 + q3
Total energy = -679 J + 160 J - 61 J
Total energy = -580 J

Therefore, 10.0 g of CCl2F2 would evolve 580 Joules of thermal energy when cooled from 40°C to -40°C.