Question

Assume that the complete combustion of one mole of ethanol to carbon dioxide and water liberates 1370 kJ of energy (Δ????°′=−1370 kJ/mol ). If the energy generated by the combustion of ethanol is entirely converted to the synthesis of a hypothetical compound X, calculate the number of moles of the compound that could theoretically be generated. Use the value Δ????°′compound X=−45.9 kJ/mol . Round your answer to two significant figures.

Answer 1

28 moles of X.

Step-by-step explanation:

Let's consider the complete combustion of ethanol.

C₂H₆O(l) + 3 O₂(g) ⇒ 2 CO₂(g) + 3 H₂O(l)

When 1 mole of ethanol burns it releases 1370 kJ, that is, the enthalpy of combustion is -1370 kJ/mol. If the energy released by one mole of etanol were used to syntesize the compound X, it would take 45.9 kJ to form 1 mole of X, that is, the enthalpy of formation is -49.5 kJ/mol. Then,

`1mol(etanhol).(-1370kJ)/(mol(etanhol)) .(1mol(X))/(-49.5kJ) =28mol(X)`