Simple And Fractional Distillation

Question 1

what is the purpose of simple distillation?

Answer 1

simple distillation is used to separate a pure liquid from a mixture, but when we want to keep the liquid e.g. pure water from salt water or separating ethanol from water. It only works if the liquids have different boiling pints

Question 2

describe the process of simple distillation

Answer 2

• the solution is placed in a flask and heated, usually using a bunsen burner
• the liquid in the mixture evaporates into a gas
• the vapour passes into a condenser where it is cooled by a water jacket and condenses back into a liquid
• the liquid is then collected into a beaker

Question 3

why can you not use simple distillation for mixtures that contain multiple different liquids?

Answer 3

if the different liquids have similar boiling points, those liquids may evaporate at the same time

Question 4

when would you need to use fractional distillation rather than simple distillation?

Answer 4

fractional distillation is used when the mixture contains multiple liquids with similar boiling points

Question 5

what is the fractionating column used in laboratory fraction distillation filled with? Explain why

Answer 5

the fractionating column is filled with small glass rods. These provide a large surface area which will cause gases to condense back into liquid if the temperature is below their boiling point

Question 6

what apparatus is needed for simple distillation?

Answer 6

• flask that contains the solution or liquid mixture that we are trying to separate
• flask is sealed at the top with a bung so that no gas can escape
• thermometer out through the bung to measure the temperature inside the flask
• condenser which consists of a main pipe
• surrounded by a water jacket which contains a stream of continually flowing cold water
• beneath the end of the condenser is a beaker which is used to capture the pure liquid
• heating device e.g. Bunsen burner that is placed under the flask

Question 7

when is fraction distillation used to separate mixtures?

Answer 7

fractional distillation is used to separate all the elements/compounds in a mixture, using their different boiling points

Question 8

what are the steps for fractional distillation?

Answer 8

boiling flask > fractionating column > condenser > beaker

Question 9

how does fractional distillation work?

Answer 9

• the solution is placed in a flask and is heated and the liquid with the lowest boiling point evaporates into a vapour and and passed through the fractionating column
• as it passes into the condenser it condenses back into a liquid and is collected in a beaker
• if other liquids evaporate by chance, they condense in the fractionating column back into the flask
• the temperature is altered to repeat the process for the liquid with second lowest boiling point which is collected in a different beaker
• the last liquid remains in the flask
• we can raise the temperature for our last liquid and boil it to make sure it is pure

Question 10

how can ethanol be separated from water?

Answer 10

• distillation apparatus set up
• mixture is boiled
• ethanol evaporates first as it has a lower boiling point than water
• ethanol vapour is cooled and condensed inside the condenser to form a pure liquid
• collected

Question 11

what are the steps for simple distillation?

Answer 11

boiling flask (heating) > evaporating > cooling > condensing