A) Draw an Energy cycle diagram linking the enthalpy of formation of ethanol with the enthalpy of combustion of its constituent elements.

Here's how to solve the problem using Hess's Law:

a) Draw an Energy cycle diagram linking the enthalpy of formation of ethanol with the enthalpy of combustion of its constituent elements.

The energy cycle diagram (Hess's Law cycle) for the formation of ethanol links the direct formation of ethanol from its elements to an alternative path involving the combustion of the elements and the combustion of ethanol.

The target reaction for the enthalpy of formation of ethanol ($\Delta H_f(\text{C}_2\text{H}_5\text{OH})$) is:
$2C(s) + 3H_2(g) + \frac{1}{2}O_2(g)