Question

*Chemical Engineering Thermodynamics

Consider a reaction hydrogen addition of C2H6 to form CH4 at 1400 o C and 10 bar.

C2H6 (g) + H2 (g) --> 2CH4 (g)

Estimate:

(1) The gas phase composition if the system starts with 1 mole of C2H6 and 2 mole of H2.

(2) What if the system starts with 1 mole of C2H6, 2 mole of H2 and 1 mole of N2?

Answer 1

(1) The gas phase composition if the system starts with 1 mole of C2H6 and 2 mole of H2.

assume 100% conversion of limiting reactant so:

1:1 ratio

mol of C2H6 = 1 , limiting reactant

C2H6 = 1 -1 = 0

H2 = 2-1 = 1

CH4 formed = 2*1 = 2

composition:

x-C2H6 = 0/(1+2) = 0

x-H2 = 1/(1+2) = 1/3 = 0.333

x-CH4 = 2/(1+2) =2/3 = 0.66

Q2)

if system:

still pretty similar, C2H6 is limiting so:

mol of C2H6 reacting = 1

C2H6 left = 0

H2 left = 2-1 = 1

CH4 formed = 0 + 1*2 = 2

N2 inert = 2

total mol = 1+2+2 = 5

so..

x-C2H6 = 0/(5 = 0

x-H2 = 1/5 = 0.20

x-CH4 = 2/5 = 0.4

x-N2 = 1/5= 0.20