The gasification of coal is a method of producing methane by the following reaction. C (s) + 2H2 (g) → CH4 (g) ∆H=?

Find ∆H by using the enthalpy changes in the following combustion reactions:

C (s) + O2 (g) → CO2 (g) ∆H=-394 kj

H2 (s) + ½ O2 (g) → H2O (l) ∆H=-286kj

CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (l) ∆H=-891kj

(A) 75 kJ

(B) - 75 kJ

(C) 1856 kJ

(D) - 1856 kJ

Hello there.

The gasification of coal is a method of producing methane by the following reaction. C (s) + 2H2 (g) → CH4 (g) ∆H=?

Find ∆H by using the enthalpy changes in the following combustion reactions:

C (s) + O2 (g) → CO2 (g) ∆H=-394 kj

H2 (s) + ½ O2 (g) → H2O (l) ∆H=-286kj

CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (l) ∆H=-891kj

(B) - 75 kJ

Using Hess' Law, we can calculate the heat of reaction of the gasification of coal. Multiplying the second reaction by 2 and reversing the third reaction:

C (s) + O2 (g) → CO2 (g) ∆H=-394 kj

2H2 (s) + O2 (g) → H2O (l) ∆H=-572kj

CO2 (g) + 2H2O (l) → CH4 (g) + 2O2 (g) ∆H=891kj

Adding the three reaction would result to

C (s) + 2H2 (g) → CH4 (g) ∆H = - 394 + - 572 + 891 = - 75 kJ

The answer is

(B) - 75 kJ