Separating mixtures

Question 1

What are the 4 ways to separate mixtures by physical methods

Answer 1

1) Filtration
2) Evaporation
3) Chromatography
2) Distillation

Question 2

Give the 4 steps of the method for the separation for rock salt

Answer 2

1) Grinding
2) Dissolving
3) Filtering
4) evaporating

Question 3

Give the method for the separation of rock salt using filtration and evaporation

Answer 3

1) Grind the rock salt with pestle and mortar
2) Add water and stir to dissolve the salt
3) Filter through filter paper in a funnel
4) evaporate in a evaporating dish

Question 4

What is chromatography

Answer 4

different dyes will wash through paper at different times
it can be used for blood samples or investigating chlorophyll

Question 5

What’s method 1

Answer 5

1) Dots of ink are put onto chromatography paper
2) A wick is cut from part of paper
3) The solvent washes the dye through the paper

Question 6

What is method 2

Answer 6

1) put spots of ink in pencil on baseline on chromatography
2) Roll the sheet up and put in a beaker
3) solvent seeps up paper, carrying the ink dyes with it
4) Each different dye will form a spot in a different place
5) you can compare forged ink to a known ink to see which it is

Question 7

Give the method for separating pure water from ink using simple distillation

Answer 7

1) Simple distillation can be used for separating out a mixture of a liquid and a solid
2) The liquid is heated and boils off. It’s then cooled, condensed and collected leaving the solid behind
3) Simple distillation is great for getting pure water from sea water or suspect tap water

Question 8

Give the steps for Fractional distillation to separate mixed liquids like crude oil

Answer 8

1) Different liquids boil off at different temperatures
- the fractionating coloumn ensures that the ‘wrong liquids’ condense back down, and only the liquid properly boiling at the temperature on the thermometer will make it to the top
-When each liquid has boiled off, the temperature reading rises until the next fraction starts to boil off
EXAMPLES:
Distilling whisky
separating crude oil into petrol , diesel and other fuels

Question 9

How do you check purity with melting and boiling points

Answer 9

A pure substance has fixed melting and boiling points
this helps us identify unknown substances
Impurities change melting and boiling points
This means you can test the purity of a substance you’ve separated from a mixture