Question

Calculate the standard heat of formation of acetaldehyde, ΔH°_f (CH₃CHO), given the following information:

CH₃CHO(g) + 5/2 O₂(g) → 2 CO₂(g) + 2 H₂O(l)     ΔH° = -1194 kJ

ΔH°_f of CO_2(g) = -394 kJ/mol

ΔH°_f of H₂O_(l) = -286 kJ/mol

Hint: use the Hess's Law equation to calculate heat of formation of CH₃CHO

-332 kJ

-166 kJ

+332 kJ

+166 kJ

Answer 1

$$\Delta H (CH_3CHO) = 2*(-394)+2*(-286)+1194 = -166$$

Answer: -166