Commercial ethanol is obtained by fermenting glucose and then distilling the ethanol…
CHEMISTRY · Single correct · A Level · Chemistry · Energetics · Energetics
Problem
Commercial ethanol is obtained by fermenting glucose and then distilling the ethanol from the reaction mixture.
Fermentation: C₆H₁₂O₆(aq) → 2 C₂H₅OH(aq) + 2 CO₂(g) ΔH = −67 kJ mol⁻¹ (per mol glucose)
Distillation: Separating 1 mol of C₂H₅OH from the mixture requires 42 kJ of heat.
Approximately how much net energy, in kJ, must be supplied (positive value) or removed (negative value) to produce 1.0 kg of purified ethanol? (Molar mass of ethanol = 46.1 g mol⁻¹)
(a) +9.1 \times 10^{2}
(b) -5.4 \times 10^{2}
(c) +1.8 \times 10^{2}
(d) -1.8 \times 10^{2}