- #1
gpmattos
- 5
- 0
Hi, i just perfomed a differential distillation experiment, the initial solution cointaned ethanol-water solution with 4.9% in mass it weighted 399.63g
Water Mass:381.25
Ethanol Mass:19.96
We distilliled the solution for 20 minutes and obtained two solutions, the distilled had 35.87g and the residue 361.21.We used a refractometer to measure the ethanol mass fraction, we made a calibration curve. And after comparing the mass fraction predicted by that curve we observed a 18% positive error in ethanol concentration. Well no problem so far.
Distilled.
Ethanol Mass: 10.517
Water Mass: 25.353Residue.
Ethanol Mass: 6.133
Water Mass: 354.987The point of making this thread is: It was expected that we would lose mass during the experiment, 2.64g. The water loss was negative (-0.5) probably due to the calibration curve error. Now, I'm trying to explain two things mainly: Why and how did we lose mass, and why did ethanol lost more mass?
I don't know if i made any mistakes but i found out that the Schmidt Number for Ethanol is actually lower than Water because Ethanol's difusivity is half that of water.
I don't have a picture of the experimental apparatus, so i'll try to explain since i didn't find nothing similar. It was a standard differential distillation apparatus but the condenser was vertical and quite tall, that's my main concern, being so tall it seems hard to me that so much mass was lost due to evaporation. Well,
Water Mass:381.25
Ethanol Mass:19.96
We distilliled the solution for 20 minutes and obtained two solutions, the distilled had 35.87g and the residue 361.21.We used a refractometer to measure the ethanol mass fraction, we made a calibration curve. And after comparing the mass fraction predicted by that curve we observed a 18% positive error in ethanol concentration. Well no problem so far.
Distilled.
Ethanol Mass: 10.517
Water Mass: 25.353Residue.
Ethanol Mass: 6.133
Water Mass: 354.987The point of making this thread is: It was expected that we would lose mass during the experiment, 2.64g. The water loss was negative (-0.5) probably due to the calibration curve error. Now, I'm trying to explain two things mainly: Why and how did we lose mass, and why did ethanol lost more mass?
I don't know if i made any mistakes but i found out that the Schmidt Number for Ethanol is actually lower than Water because Ethanol's difusivity is half that of water.
I don't have a picture of the experimental apparatus, so i'll try to explain since i didn't find nothing similar. It was a standard differential distillation apparatus but the condenser was vertical and quite tall, that's my main concern, being so tall it seems hard to me that so much mass was lost due to evaporation. Well,