(Solved): (c) Methane gas (natural gas) is bumed to produce energy for generating electricity, heating and co ...

(c) Methane gas (natural gas) is bumed to produce energy for generating electricity, heating and cooking, as represented in the following reaction: \[ \mathrm{CH}_{4}(\mathrm{~g})+2 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \] (i) Use the mean bond enthalpies \( \left(\mathrm{kJ} \mathrm{mol}^{-1}\right) \), shown in the table below, to calculate the enthalpy change for the above equation. Give the correct SIGN and UNITS. (4 marks) (ii) The experimental value for the enthaipy of combustion of methane is \( -890 \mathrm{~kJ} \mathrm{~J} \mathrm{~mol}^{-1} \). Explain why this value differs from your answer to (i). (1 mark)