Required Practical 12 - Chromatography Flashcards
1
Q
Equipment
A
food colouring (unknown) food colourings(known)
2
Q
Method
A
- Ruler drawn with pencil across chromatography paper around 2cm off bottom
- Equidistant lengths apart dot the ink using a capillary tube
- Pour water into beaker depth of 1cm
- Attach paper to glass rod and gently lower paper into water
- Water moves up paper and remove paper when water is ¾ up and draw line across that
- Hang paper up to dry
- Unknown colours spots shows which it contains and how much it’s a mixture of
- Look up Rf value of substance and find what chemicals it is
3
Q
Why should the ink dots be kept small?
A
To stop them spreading into each other
4
Q
The pencil line must stay …
A
Above water level
5
Q
What happens if the paper touches the sides
A
Interferes with the way water moves
6
Q
Place lid on beaker to …
A
Reduce evaporation of solvent
7
Q
Rf Value eqaution
A
Distance travelled by substance / distance travelled by solvent
