Ethene (C2H4) can be halogenated by the reaction: C2H4( g )+X2( g )?C2H4X2( g )

ID: 702857 • Letter: E

Question

Ethene (C2H4) can be halogenated by the reaction:
C2H4(g)+X2(g)?C2H4X2(g)
where X2 can be Cl2, Br2, or I2.

Use the thermodynamic data given to calculate ?H? for the halogenation reaction by Cl2.

Use the thermodynamic data given to calculate ?S? for the halogenation reaction by Cl2.

Use the thermodynamic data given to calculate ?G for the halogenation reaction by Cl2 at 18 ?C.

Use the thermodynamic data given to calculate Kp for the halogenation reaction by Cl2.

Compound ?H?f(kJ/mol) ?S?f(J/mol?K) C2H4Cl2(g) -129.7 308.0 C2H4Br2(g) -38.3 330.6 C2H4I2(g) 66.5 347.8

For Cl2

C2H4(g)+Cl2(g)?C2H4Cl2(g)

?H° = ?Hf (C2H4Cl2) - ?Hf (Cl2) - ?Hf (C2H4)

= - 129.7 - 0 - 52.47

= ?182.17 kJ/mol

?S? = ?Sf (C2H4Cl2) - ?Sf (Cl2) - ?Sf (C2H4)

= 308 - 222.8 - 219.4

= ?134.2 J/mol·K

?G? = ?H° - T?S?

= ?182.17*1000 - 298*( ?134.2)

= ?142178.4 J/mol

= - 142.178 kJ/mol

?G? = - RT ln K

142178.4 = 8.314*298 ln K

K = 8.314 x 10^24

?G =?G? + RT ln K

= 142178.4 + 8.314*(18+273)*ln (8.314 x 10^24)

= 281002.08 J/mol

= 281 kJ/mol

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