Question

The reaction, C₂H₆(g) + Cl₂(g) àC₂H₅Cl (g) + HCl (g), occurs in a continuous flow reactor. 100 mol/hr of ethane and 125 mol/hr chlorine gas @ 25°C are fed to the reactor. Assume complete reaction of ethane. The reactor exit stream temperature is 200°C. Calculate the moles of each component of the feed and exit streams and the extent of reaction z. Calculate the heat released or absorbed (specify which) from the reactor using the heat of reaction method. The chloroethane heat capacity can be found in Perry's. For the C_pvalues from Table B.2 in your text, you may use just the “a” and “b” terms for simplicity.

Answer 1

Solution

as given in the question feed has only two components ethane and chlorine

feed stream

100 moles/hr C₂H₆ and 125 moles/hr Cl₂

in terms of mole fraction

C₂H₆ mole fraction 0.444

Cl₂ mole fracton 0.556

for exit stream in terms of moles and mole fraction

C₂H₆ 00 moles/hr and 00

Cl₂ 25 moles/hr and 0.111

C₂H₅Cl 100 moles/hr and 0.444

HCl 100 moles/hr and 0.444

extent of reaction for ecch of the species is same

z = 100

C_p(C₂H₆) = 52.98 KJ/(Kmol.K)

C_p(Cl₂) = 29.2125 KJ/(Kmol.K)

C_p(C₂H₅Cl) = 62.78 KJ/(Kmol.K)

C_p(HCl) = 30.8 KJ/(Kmol.K)

heat of formation of Chloro ethane -105 KJ/mol

heat relesed when 100 mol of chloroethane formed 10500 KJ

heat consumed by 25 moles of chlorine to raise the temp from 25 to 200 = 25*29.2125*175 = 129.318 KJ

heat consumed by 100 moles of hydro-chloric acid to raise the temp from 25 to 200 = 100*30.8*175 = 539 KJ

heat consumed by 100 moles of chloroethane to raise the temp from 25 to 200 = 100*62.78*175 = 1098.65 KJ

total heat consumed = 1766.968 KJ

heat release during reaction = 10500 KJ

heat removed from the reactor = 10500 - 1766.968 = 8733.032 KJ

8733.032 KJ of heat is removed and release to the enviroment