Question

physical chem

Industrially, acetic acid (CH3CO2H(l)) is made by oxidizing ethanol (CH3CH2OH(l)) with oxygen over a catalyst in a continuous flow reactor. In industry one must be concerned with either adding or removing heat from processes. If acetic acid is being oxidized at a rate of 35Kg/hr. At what rate must heat be added or removed to maintain the process at 25˚C?

Answer 1

Ans. Balanced reaction:

C₂H₅OH(l) + O₂(g) -----> CH₃COOH(l) + H₂O(l)   ; dH⁰ = -492 kJ/ mol

The –ve sign indicates that the reaction is exothermic.

# During the process, ethanol (but NOT acetic acid) is being oxidized .

So, it’s assumed that “if ethanol is being oxidized at rate of 35 kg/hr”.

# Moles of ethanol being oxidized = Mass of ethanol in gram / Molar mass

                                                = 35000 g / (46.06904 g/ mol)

                                                = 759.729 mol

Hence, rate of ethanol oxidation = 35 kg/ hr = 75.729 mol/ hr

Now,

Amount of heat released = Rate of ethanol oxidation x Molar enthalpy of reaction

                                                = (75.9729 mol/ hr) x (- 492 kJ/ mol)

                                                = -373786.82 kJ/ hr

Therefore, rate of removing heat = -373786.82 kJ/ hr