Question

Energy of reactions and Reaction kinetics

1.   The combustion of methane (natural gas) occurs by the reaction

           CH₄ (g) + O₂ (g) ---> CO₂ (g) + H₂O (l )      ΔH^o = -890 kJ

·     Write the balanced equation.

·     Is this an endothermic or an exothermic reaction? Justify your answer.

·     Calculate the energy produced (or absorbed) when 2.7 mol of methane burn with excess O₂.

·     Calculate the energy produced (or absorbed) when 15 g of methane burn with excess O₂.

Answer 1

Balanced

CH4(G) + 2O₂(G) → CO₂(G) + 2H₂O(G)

The energy given off is negative and thus the reaction is exothermic. ΔH^o = -890 kJ

Energy ( methane ) = 2.7 × -890 = 2403 kJ

Energy (15g) $= \frac {15}{16.04} ×( -890)=-832.3 kJ$