Investigating Chromatography

Question 1

What is the required equipment for investigating chromatography?

Answer 1

-Chromatography paper
-100cm cubed beaker with lid
-Pencil and ruler

Question 2

What chemicals are required for investigating Chromatography?

Answer 2

-Distilled Water
-4 known food colouring.
-Unknown food colouring mixture

Question 3

What method is used for investigating chromatography?

Answer 3

-Draw a pencil line 2 cm from the bottom of the chromatography paper.
-Make 5 pencil spots along this horizontal line, ensuring that the marks are spread across the line.
-Add each food colouring onto each o the pencil spots.
-Place chromatography paper in a beaker containing 1cm of water. Place a lid on the beaker to prevent evaporation of the solvent, and wait for the water to travel most of the way up.
-Once the paper has travelled 2/3 of the way up to paper, remove from the beaker and draw a line of the maximum point it reached up to.
-Once paper has dried, calculate the Rf values and compare values of the known food colourings with the unknown mixure.

Question 4

Safety precautions for investigating Chromatography

Answer 4

-Take care when handling glassware.
-Clear up broken glassware immediately.
-Avoid touching food colourings, they will stain skin.

Question 5

What can be analysed from this experiment?

Answer 5

-The Rf value of each spot on the chromatogram should be calculated.
-If the Rf value of a known food colouring maths the spot in unknown mixture, it is likely the food colouring is one of the components in the mixture.
-If 2 substances are the same, they will travel up to the same distance on the chromatography paper.

-Rf=distance travelled by substance + distance travelled by solvent front.