Example 2.25:  Acetylene can be made by the reaction of carbon and hydrogen.  Calculate the equilibrium constant at 2300 °C.  Use the following data: 

 

 

Specific heat is given by Cp = a + bT + cT2 and their values are tabulated.

 

 

i

 

 

 

ai

 

bi

 

ci

 

υi

 

1

 

C(s)

 

1.1

 

4.8 ´ 10-3

 

-1.2 ´ 10-6

 

-2

 

2

 

H2

 

6.88

 

5.6 ´ 10-5

 

-2.79 ´ 10-7

 

-1

 

3

 

C2H2

 

8.28

 

1.05 ´ 10-2

 

-2.644 ´ 10-6

 

1

 

Solution

$                    a = Sυiai = -0.8

$                    b = Sυi bi = 8.44 ´10-4

$                    c = Sυici = 3.5 ´ 10-8

$                    Integration constant, ΔHo (Equation 2.69)

$                    Integration constant, ΔSo (Equation 2.70)

 

$                    Energy of formation, ΔG (Equation 2.71):

$                    Equilibrium constant,