Distillation.pdf - Microsoft Edge online.ksu.edu/COMS/player/content/_16794/cont
ID: 932969 • Letter: D
Question
Distillation.pdf - Microsoft Edge online.ksu.edu/COMS/player/content/_16794/content/Modules/Distillation.pdf 0O DISTILLATION The PreLab Exercise A mixture of 40 mL of methyl butyrate (MW= 102.1 g/mol, d=0.89 g/mL) and 10 mL butyric acid (MW-881 g/mol, d=0.96 g/mL) is distilled Calculate the mole percent of each component, and using these mole percents and the figure below, answer the following questions: 1. What is the initial boiling point of this mixture? 2. What is the composition of the vapor in equilibrium with this liquid? What is the composition of the intial condensate from simple distillation? 3. Instead of a simple distillation, you set up a fractional distillation. Assuming three theoretical plates, what is the composition of the first fraction collected? 170 160 150 140 130 120 110 100 90 170 160 150 140 130 Gas Temp (C) 120 110 100 90 methyl butyrate butyric acid 100 60 20 20 60 100 t O Ask me anything 2:12 PM 12/20/2015Explanation / Answer
40 mL x 0.89 g/mL / 102.1 g/mol = 0.35 mol MB
10 mL x 0.96 g/mL / 88.1 g/mol = 0.11 mol BA
Total moles ……………………..0.46 mol
MB mol % = 100 x 0.35/0.46 = 76%
BA mol % = 100 x 0.11/0.46 = 0.24%
(in the image try to draw the first vertical line closer to MB80%.
1.The boiling point is the temperature of the first horizontal line, my estimation is about 103..104ºC.
2. look at the left end of the first horizonthal line, draw a vertical line and read the composition on the abscissa : 95% MB and 5% BA. These values are the vapour composition and the composition of the distillate for a simple distilation (same values).
3. Each horizontal line is a vaporizaton. Each vertical line is a condensation. Each pair vaporization-condensation is a theoretical plate. For three theoretical plates, the distilate (first fraction) is very close to pure MB (>99%).
Note. Observe that after the collection of the first fraction, you have to rise the temperature to 160 ºC to start a vaporization of the remainng pure BA.