Pre Lab Experiment 1: Distillation Flashcards
What is distillation used for? What is the overview of this method?
To purify and separate liquids
1) Evaporation of a liquid from a mixture
2) Condensation
3) Condensate collected in a separate container
What are 3 requirements for distillation?
1) At least one component in the mixture must be volatile
2) 50 degree boiling point difference is required to separate two volatile liquid by distillation
3) No Azeotropes: mixture of fixed composition that acts as a pure compound with fixed boiling point
What is the difference between simple and fractional distillation?
1) Simple distillation -Heat –> Cool –> Collect (not as good)
2) Fractional distillation -Heat –> Cool –> “Collect” Many times (better)
What 2 compounds are we using in this lab?
Acetone and Toluene
What must we do to the thermometer before this lab?
Calibrate unused thermometer
What safety precaution must we consider in this lab?
Don’t let residue dry out, it will cause explosion
What is refraction index dependent on?
Temperature. You must take the temperature reading when you measure the refractive index
What is the refractive index equation?
R.I. = velocity of light in air/velocity of light in liquid
How many decimals do we need for refractive index?
4 decimals
Where do we dispose the distillate in this particular lab?
Recycle all the distillate collected in the special container in fumehood.
What are the results of this lab (effectiveness between simple and fractional distillation)?
1) Fractional distillation is better at separating and purifying liquids (at 30mL, only 1.2% acetone –> 99% toluene. At 10mL, 92% acetone)
2) Simple Distillation (at 30mL, still 11.2% acetone. At 10mL, 40.6% acetone).
Based on the results, Fractional Distillation is much better at separating and purifying liquids.
Why is fractional distillation better than simple distillation? How does fractional distillation work?
The final distillate will be nearly pure. It is very good at separating a mixture.The fractional column permits this repeated exchange of molecules between the liquid and vapour phases. Packed with round glass beads that provide a large cooling surface for multiple condensations and vaporizations to take place.
