Chromotography Paper 2-RP 5

Question 1

What is the aim?

Answer 1

Investigate how paper chromatography can be used to separate coloured substances

Question 2

What is the method for the pratical?

Answer 2

-Use ruler and draw horizontal line 2 cm above paper bottom.
-Mark 5 pencil spots across line 1 cm apart at each side.
-Use capillary tube to put small spot of know food colours and unknown
-Pour water into a beaker of 1 cm
-Attach paper to glass rod on beaker ensuring bottom off paper dips
-Water will move up and colours carried up ensure beaker isn’t moved and remove paper once water has travelled 3/4 up.
-Use pencil line to mark points where water has reached and hang paper to dry.

Question 3

What should the samples be?

Answer 3

Four know food colourings and and unknown sample of food colouring

Question 4

What are the control variables?

Answer 4

-Pencil above surface of water or ink will dissolve
-Sides of paper not touching beaker may interfere with water movement.
-Lid on beaker to reduce evaporation.

Question 5

What should the unknown colour do?

Answer 5

Separate into other colours

Question 6

How do you find Rf values?

Answer 6

Distance travelled by substance/Distance travelled by solvent