rp exam qs paper 2

Question 1

Propanone can be made by reacting propan-2-ol with an excess of
acidified potassium dichromate(VI).
The propanone is removed from the reaction mixture by distillation.
0 3 . 1 Figure 2 shows the apparatus set up by a student to make propanone by this method.
Suitable clamps are used to hold all the apparatus firmly in place.
There are three problems with the apparatus set up in Figure 2.
For each problem:
* identify the problem
* describe the issue it would cause
* suggest how the problem can be solved

Answer 1

Anti-bumping granules
1a no anti-bumping granules / add anti-bumping
granules
1b to create smaller bubbles / to prevent large
bubbles / to prevent mixture jumping into
condenser
Stage 2
Open system with no thermometer
2a system should be closed (above flask) to
prevent gases escaping
2b should be closed with (bung +) thermometer
2c to allow collection of propanone (only) / to
prevent distillation of other components / to
stay in suitable temperature range
Stage 3
The water direction in the condenser
3a water flows in wrong direction through
condenser / change water direction
3b condenser not cool enough / not full of water
3c product may not condense / comes through as
gas