Question

Estimate the amount of heat released (in kj/mol) when 10g of CH4 gas reacts with an excess of O2 gas to form gaseous CO2 and liquid water. The molar mass of CH4 is 16.042

Answer 1

CH₄(g) + 2O₂(g) = CO₂(g) + 2H₂O
(liq)∆H = 2∆H(H₂O) + ∆H(CO₂) - ∆H(CH₄)
∆H = 2 * (-285,8) +(-393,5) + 74,6 = -890,5 kj/mol
Q = n * ∆H;
n = 10/16.042 = 0.623 mol;
Q = 0.623 mol * (-890,5 kJ/mol);
Q = -555.11 kJ