Part A: Acetylene, C2H2, can be converted to ethane, C2H6, by a process known as
ID: 507033 • Letter: P
Question
Part A:
Acetylene, C2H2, can be converted to ethane, C2H6, by a process known as hydrogenation. The reaction is
C2H2(g)+2H2(g)?C2H6(g)
Given the following data at standard conditions (all pressures equal to 1 atm and the common reference temperature 298 K), what is the value of Kp for this reaction?
In Part A, we saw that ?G?=?242.1 kJ for the hydrogenation of acetylene under standard conditions (all pressures equal to 1 atm and the common reference temperature 298 K). In Part B, you will determine the ?G for the reaction under a given set of nonstandard conditions.
Part B
At 25 ?C the reaction from Part A has a composition as shown in the table below.
What is the free energy change, ?G, in kilojoules for the reaction under these conditions?
Express your answer numerically in kilojoules.
Substance ?G?f(kJ/mol) C2H2(g) 209.2 H2(g) 0 C2H6(g) ?32.89
Explanation / Answer
C2H2(g)+2H2(g)C2H6(g)
Kp = PC2H6 / PC2H2 * PH22
Kp = (5.25*10-2) / (4.85 * 5.152)
Kp = 0.000408
We know that,
G = G0 + R T lnKp
G = - 242.1 + (0.008314 * 298 * ln0.000408)
G = - 261.4 kJ