Question

Methane is the major component of natural gas. The standard molar enthalpy of formation of methane CH4 is -74.9 kJ/mol. For the balanced reaction equation of methane use:
CH4 + 2O2 --> CO2 + 2H2O.

All the chemicals in this reaction are gases. What is the enthalpy change of this reaction in kJ/mol?

Answer 1

Answer:

$\Delta _rH=-802.2kJ/mol$

Explanation:

Hello!

In this case, according to the given chemical reaction, it is possible to calculate the enthalpy change of the reaction via:

$\Delta _rH=\Delta _fH_{CO_2}+2\Delta _fH_{H_2O}-\Delta _fH_{CH_4}$

Since the enthalpy of formation of oxygen is 0. Thus, given the enthalpies of formation of gaseous carbon dioxide and water, we obtain:

$\Delta _rH=(-393.5kJ/mol)+2(-241.8kJ/mol)-(-74.9kJ/mol)\\\\\Delta _rH=-802.2kJ/mol$

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