Question

Use average bond energies to estimate the energy released when 50.0 g CH4 undergoes complete combustion:

CH4​(g)+2O2​(g)CO2​(g)+2H2​O(g)

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Answer 1

Explanation:

11900kJ is the answer

The problem provides you with the thermochemical equation that describes the combustion of methane, CH4

CH4(g)+2O2(g)→CO2(g)+2H2O(g) ΔH=−802.3 kJ mol−1

The enthalpy change of combustion, given here as ΔH, tells you how much heat is either absorbed or released by the combustion of one mole of a substance.

In your case, the enthalpy change of combustion

ΔH=−802.3 kJ mol−1

suggests that the combustion of one mole of methane gives off, hence the minus sign, 802.3 kJ of heat.

Your strategy here will be to use the molar mass of methane to convert your sample from grams to moles

Since you know that 1 mole produces 802.3 kJ of heat upon combustion, you can say that 14.776 moles will produceThis is equivalent to saying that the enthalpy change of reaction, ΔHrxn, when 237 g of methane undergo combustion is

=11900kj