Question

The enthalpy of combustion of ethyl alcohol (C2H5OH) is 1380.7 KJ mol-1.If the enthalpy
of formation of CO2 and H2O are 394.5 and 286.6 KJ mol-1 respectively, calculate the
enthalpy of formation of ethyl alcohol.

Answer 1

1. you have to write the equation of combustion of the ethyl alcohol and figure out how many moles of CO2 and H2O are produced by the combustion of one mole of ethyl alcohol.

2.multiply the enthalpy of formation of CO2 and H2O by the respectively number of moles calculated before and add these two values.

3.Subtract the value calculated in 2 from the enthalpy of combustion of the ethyl alcohol data given in the problem. This is going to be the entalphy of formation of the ethyl alcohol since the entalphy of formation of the O2 will be =0 because is an element in his standard state.

Answer 2

thank you