Question

Alcohol is used as a source of fuel for some automobiles. The standard molar enthalpy of formation of ethanol C2H5OH(l) is -277.6 kJ/mol. For the balanced reaction equation of ethanol use:

C2H5OH(l) + 3O2 --> 2CO2 + 3H2O.

Ethanol is a liquid, but all the other chemicals in this reaction are gases. What is the enthalpy change of this reaction in kJ/mol?

Answer 1

`\Delta _rH=-1,234.8kJ/mol`

Step-by-step 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=2\Delta _fH_(CO_2)+3\Delta _fH_(H_2O)-\Delta _fH_(C_2H_5OH)`

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=2(-393.5kJ/mol)+3(-241.8kJ/mol)-(-277.6kJ/mol)\\\\\Delta _rH=-1,234.8kJ/mol`

Best regards!