Question

How much heat is produced by the complete combustion of 265g of CH4?
CH4(g)+2O2(g)→CO2(g)+2H2O(g)ΔH∘rxn=−802.3kJ

Answer 1

Answer on Question #40878 - Chemistry - Other

Question

How much heat is produced by the complete combustion of 265g of CH₄?

$$\mathrm{CH_4}(g) + 2\mathrm{O_2}(g) \rightarrow \mathrm{CO_2}(g) + 2\mathrm{H_2O}(g) \quad \Delta H?r \times n = -802.3\ \mathrm{kJ}$$

Answer:

$\Delta H?r \times n = -802.3\ \mathrm{kJ}$ means that 802.3 kJ of heat are produced by the complete combustion of 1 mol of methane. So we should calculate the number of moles of methane to find out the amount of heat produced by this reaction.

Number of moles equals:

$$n = \frac{m}{M}$$

m – Mass of the methane, m = 265 g.

M – Molar mass of methane, g/mol:

$$M(CH_4) = M(C) + 4M(H) = 12 + 4 \cdot 1 = 16\ g/mol$$

Then number of moles of methane is:

$$n(CH_4) = \frac{m(CH_4)}{M(CH_4)} = \frac{265}{16} = 16.6\ mol$$

Then we make a proportion:

Combustion of 1 mol of CH₄ produces 802.3 kJ of heat

Combustion of 16.6 mol of CH₄ – x kJ of heat

$$x = \frac{16.6 \cdot 802.3}{1} = 13318.2\ \mathrm{kJ}$$

Answer: 13318.2 kJ of heat are produced by the complete combustion of 265 g of CH₄.