Question

Sulfur dioxide is produced in enormous amounts for sulfuric acid production. It melts at −73°C and boils at −10°C. Its ΔH°fus is 8.619 kJ/mol and its ΔH°vap is 25.73 kJ/mol. The specific heat capacities of the liquid and gas are 0.995 J/g · K and 0.622 J/g · K, respectively. How much heat is required to convert 2.585 kg of solid SO2 at the melting point to a gas at 60°C?

Answer 1

Mass of SO2 solid = 2585 g.

In solid state energy used in converting solid to liquid at -73'C = no. of moles of SO2*8.619 KJ

molar mass of SO2 = 32+32=64

No. of moles of SO2 = 2585/65

= 40.39 moles

So amout of heat required = 40.39*8.619 KJ

= 348.12 KJ .......................(1)

Amount of heat required for liquid SO2 from -73'C to -10'C = (73-10)*0.995*2.585

= 162.04 KJ......................(2)

Heat required for converting S)2 into gas = 40.39*25.73

= 1120.0147 KJ (at -10'C)............................(3)

Amount of heat reqired to raise the temperature of SO2 gas from -10 to 60'C = (60+10)*0.622*2.585

= 112.55 KJ..........(4)

Total heat required = (1)+(2)+(3)+(4)

= 1742.72KJ