Calculate the H of the following reaction, which describes the production of coal gas from carbon, given the steps below.

H2O (g) + C (s) CO (g) + H2 (g)


Given Steps

H2 (g) + 1/2 O2 (g) H2O (g) H = - 242.0 kJ
2CO (g) 2 C (s) + O2 (g) H = + 221.0 kJ

 

Asked by Topperlearning User | 15th Jun, 2016, 05:35: PM

Expert Answer:

1) The overall equation is written above.
Note that the H2O (g) is a reactant and in step #1 it is a product. Thus step one needs to be reversed and the sign of the heat changed.
Note that 1 mole of CO (g) is a product in the overall equation, but 2 moles of CO (g) is a reactant in step 2 . Thus step two needs to be reversed, and divided by two.

2) Manipulated equations

H2O (g)
H2 (g)
+
1/2 O2 (g)
H
=
 + 242.0 kJ
C (s)
+
1/2 O2 (g)
CO (g)
H
=
 - 110.5 kJ
 
3) Add equations and heats
H2O (g)
+
C (s)
+
1/2 O2 (g)
1/2 O2 (g)
+
H2 (g)
+
CO (g)
H = +131.5 kJ
 
Substances in bold above are common and therefore are canceled
 
Net Equation:
H2O (g)
+
C (s)
H2 (g)
+
CO (g)
H = +131.5 kJ

 

Answered by  | 15th Jun, 2016, 07:35: PM