The balanced combustion of methane is shown below.

Question

CH4(g) + O2(g)  CO2(g) + H2O(g) ΔH = –890 kJ mol–1
Determine how much energy is released when 60 L of methane at 25 MPa and 25°C undergoes complete combustion.

Answer 1

First, we need to calculate the number of moles of methane present in 60 L at 25 MPa and 25°C. We can use the ideal gas law:

PV = nRT

n = (PV)/(RT)

n = ((25 MPa) x (0.06 m3))/(8.314 J/mol∙K x 298 K)

n = 0.00968 mol

According to the balanced equation, 1 mole of methane releases 890 kJ of energy. Therefore, 0.00968 mol of methane will release:

0.00968 mol x (-890 kJ/mol) = -8.61 kJ

The negative sign indicates that energy is released (exothermic reaction).

Therefore, the combustion of 60 L of methane at 25 MPa and 25°C will release 8.61 kJ of energy.