Chromatography RPA

Question 1

Method

Answer 1

1) Take chromatography paper and turn it portrait- with pencil and ruler draw horizontal line (baseline) across paper near the bottom
2) use pencil to mark (5) dots equally spaced apart across the baseline
3) use capillary tube to add small sample of (ink) onto each dot
4) using measuring cylinder pour shallow amount of water into beaker
5) attach top of paper to glass rod using tape then lower into beaker ensuring the baseline is above the water but bottom of paper is in water
6) place a lid on the beaker and wait for solvent to move three quarters of the way up the page
7) use a pencil t mark the point where the water reached then remove the paper from the water and hang it up to dry
8) use ruler to measure distance solvent moved (using pencil mark) and distance each sample moved then calculate Rf value by doing distance moved by substance/ distance moved by solvent

Question 2

Rf value meaning

Answer 2

Ratio between distance travelled by solute (dissolved substance) and distance travelled by solvent

Question 3

Name for bits of ink etc that move up the paper

Answer 3

Solute (dissolved substance)

Question 4

How close to bottom of paper should pencil line be

Answer 4

2cm

Question 5

How much water should be in the beaker

Answer 5

1 cm cubed

Question 6

Stationary phase meaning

Answer 6

Chromatography paper

Question 7

Mobile phase meaning

Answer 7

Solvent

Question 8

What can affect the Rf value

Answer 8

Solvent used

Question 9

2 things that affect how long molecules stay in stationary phase (paper) vs mobile phase (solvent)

Answer 9

How soluble they are
How much they’re attracted to the paper