Question

The following reaction evolves 1389 kj of heat energy to the surrounding when 25.0h of CH4 is combusted with excess O2 as follows: CH4 + 2O2 = CO2 + 2H20

what is the enthalpy of reaction (deltaH) in kilojoules per mole of methane?

Answer 1

Answer on Question #82256, Chemistry/ General Chemistry

The following reaction evolves 1389 kJ of heat energy to the surrounding when 25.0 h of CH4 is combusted with excess O2 as follows: CH4 + 2O2 = CO2 + 2H2O

what is the enthalpy of reaction (deltaH) in kilojoules per mole of methane?

Solution

$$\mathrm{CH_4} + 2\mathrm{O_2} = \mathrm{CO_2} + 2\mathrm{H_2O}$$ $$n = \mathrm{m/M}$$ $$n(\mathrm{CH_4}) = 25.0\ \mathrm{g} / 16\ \mathrm{g/mol} = 1.56\ \mathrm{mol}$$

when 1.56 mol of methane is combusted 1389 kJ of heat is evolved

when 1 mole of methane is combusted x kJ of heat is evolved

Solve the proportion:

$$\frac{1.56}{1} = \frac{1389}{x}$$ $$x = 890$$ $$\Delta H = 890\ \mathrm{kJ/mol}$$

Answer: 890 kJ/mol

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