Distillation

Question 1

what is distillation used for and what are the two different types?

Answer 1

• it is used to separate mixtures that contain liquids
• the two types are: simple and fractional

Question 2

what is simple distillation used for?

Answer 2

to separate out a liquid from a solution

Question 3

simple distillation method

Answer 3

1. the solution is heated - the part of the solution that has the lowest boiling point evaporates
2. the vapour is then cooled, condenses and is collected
3. the rest of the solution is left in the flask
4. simple distillation can be used to get pure water from sea water - the water evaporates and is condensed and collected, and eventually all that is left in the flask is the salt

Question 4

what is the problem with simple distillation?

Answer 4

it can only be used to separate things with very different boiling points - if you have a mixtures with similar boiling points, you need to use fractional distillation

Question 5

what is fractional distillation used for?

Answer 5

to separate a mixture of liquids

Question 6

fractional distillation method

Answer 6

1. put the mixture in a flask and stick a fractionating column on top, then heat it
2. the different liquids will all have different boiling points, and so they will evaporate at different temperatures
3. the liquid with the lowest boiling point evaporates first - when the temperature on the thermometer reaches the boiling point of this liquid, it will reach the top of the column
4. liquids with higher boiling points might also start to evaporate - but the column is cooler at the top so they will only get part of the way up before condensing and running back down towards the flask
5. when the first liquid has been collected, you raise the temperature until the next one reaches the top