Experiment 3: Fermentation & Distillation of Ethanol via Simple & Fractional Distillation Flashcards
When conducting a “safe” distillation in the lab, which of the following should always be done?
I. a boiling chip should be placed in the distillation flask
II. the glassware joints should be lightly greased
III. all openings should be sealed including the attachment of the receiving flask to the apparatus, to ensure an air-proof, water-proof system
only I & II
Which of the following statement(s) is/are TRUE?
I. At the beginning of a distillation (t=0 where t represents time), the vapor phase contains more of the high boiling component of the mixture.
II. Temperature is constant while a compound is distilling as long as the composition of the mixture isn’t changing.
III. The process of condensation, vaporization causes the vapor to become enriched in the less volatile component.
IV. Temperatures will change during a phase change as long as the mixture is being heated.
only II. Temperature is constant while a compound is distilling as long as the composition of the mixture isn’t changing.
In fractional distillation, a large surface area fro condensation is provided through?
a fractionating column
Distillate is a liquid that…
condenses after distillation
What is the point of using a boiling stone or stir stick when heating a liquid?
to provide a surface on which gas bubbles can form in the liquid to avoid superheating
When should you record the first boiling point range during a distillation?
when the vapor condenses to form a drop of liquid on the bulb of the thermometer and the temperature stabilizes
! Where should the bulb of the thermometer be placed to get an accurate reading?
It should be aligned slightly below the opening of the 3-way adapter leading to the condenser.
! How is the actual ethanol content (% ethanol) of the distillate determined?
the density of the distillate is found & the correlation between density and % ethanol by weight or volume is looked up in a “Table”which lists % alcohol values
Which of the following statements is/are NOT true about a distillation set-up?
I. the water hoses must be securely attached to the condenser & faucet
II. the water will enter from the top of the condenser and exit from the bottom of the condenser so that it flows “downward”
III. the water serves to cool the vapors causing them to condense
IV. the lowest boiling liquid will be collected first
only II
What is an azeotrope?
a mixture of 2 or more liquids with a constant boiling point
You have a mixture of 3 compounds. Which of the following compounds would distill first and which compound would distill last?
Compound B would distill first and compound C would distill last.
When should you record the boiling point range during a distillation?
when the vapor condenses to form a drop of liquid on the bulb of the thermometer & the temperature stabilizes
What is forerunner?
a low boiling liquid that sometimes distills over long before the boiling point of the liquid you want has started to boil
