Worksheet: Rotary Evaporation

In this worksheet, we will practice describing the removal of solvent in vacuo by rotary evaporation, assessing hazards and common errors.

Q1:

Which component of a rotary evaporator is typically secured with a Keck clip?

  • AEvaporating flask
  • BCollecting flask
  • CSplash guard
  • DWater bath
  • ECondenser

Q2:

Which component of a rotary evaporator is typically secured with a pinch clamp?

  • ASplash guard
  • BEvaporating flask
  • CCondenser
  • DWater bath
  • ECollecting flask

Q3:

Which piece of apparatus is not used in the normal operation of a rotary evaporator?

  • ATwo-necked flask
  • BVacuum pump
  • CCondenser
  • DWater bath
  • EKeck clip

Q4:

When removing a solvent in a rotary evaporator, which of the following steps is not required?

  • AThe pressure in the flask is accurately measured.
  • BThe solution is placed in a round-bottom flask.
  • CThe condenser is filled with dry ice and acetone or a water flow.
  • DThe collected solvent is disposed of safely.
  • EA Keck clip is used to secure the flask in place.

Q5:

When performing a rotary evaporation, which of the following is not a reason for lowering the pressure gradually?

  • AVigorous boiling may force solution out of the flask.
  • BThe rate of evaporation is more easily controlled.
  • CThe solvent may freeze.
  • DThe condenser may be less effective at very low pressures.
  • EThe contents of the flask may foam.

Q6:

When performing a rotary evaporation, which of the following is not a reason for setting a low water bath temperature?

  • AVigorous boiling may force solution out of the flask if the temperature is too high.
  • BHeating may cause solutes to precipitate.
  • CHeating may cause undesirable reactions of the flask contents.
  • DThe solvent vapor may not condense if the flask temperature is too high.
  • EThe rate of evaporation is more easily controlled.

Q7:

When performing a rotary evaporation, which of the following is the best immediate course of action if the solvent starts to bump?

  • ATurning off the pump
  • BRaising the flask from the water bath
  • COpening the tap to introduce air into the system
  • DStopping the rotation
  • EIncreasing the set pressure

Q8:

When a rotary evaporation is complete, in which order should the following actions be performed?

  1. Introducing air into the system
  2. Turning off the pump
  3. Stopping the flask rotation
  • A3, 1, 2
  • B3, 2, 1
  • C1, 3, 2
  • D1, 2, 3
  • E2, 3, 1

Q9:

When setting up a rotary evaporation, in which order should the following actions be performed?

  1. Lowering the flask into the water bath
  2. Gently applying the vacuum
  3. Starting the flask rotation
  • A3, 1, 2
  • B1, 2, 3
  • C2, 1, 3
  • D3, 2, 1
  • E2, 3, 1

Q10:

The water bath of a rotary evaporator is set to 50C. Which of the following solvents could be removed safely and efficiently at this temperature?

  • ADichloromethane
  • BWater
  • CAcetone
  • DChloroform
  • EDiethyl ether

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