Required Praticle: Chromotography. Flashcards
1
Q
What is the first step for paper chromotography?
A
- The first step for paper chromotograpgy is:-
- Drawing a horizontal pencil line using a ruler on the chromotography paper, 2 cm from the bottom.
2
Q
What is the second step for paper chromotography?
A
- Mark 5 pencil spots at equal space across the line.
and - ## Using a capillary tube to put a small spot each known food colourings and the unknown on the pencil spot.
- Capilarry is a small thin glass tube.
- Keep the dots small to prevent them from spreading out to eachother.
3
Q
What is the third for paper chromotography?
A
- Pour 1cm of water into a beaker (Solvent)>
- Attach the paper onto a glass rod using tape and lower the paper into the beaker.
- Bottom of the paper should dip into the solvent.
- Pencil line must be above the surface of the water or the water will wash the ink off the line.
- Sides of the paper must not touch the sides of the walls of the beaker.
: Interfere with the way the water moves.
-
4
Q
What is the fourth for paper chromotography?
A
- Put an lid on the beaker to prevent evaporation.
- Solvent will move up the paper and the colours will be carried up.
- Make sure not to move the beaker.
5
Q
What is the fifth step for paper chromotography?
A
- Remove the paper when the water has travelled 3 quarters up.
- ## Use a pencil line to mark where the water has reached.
6
Q
How do we calculate the Rf values?
A
- Measure the distance from the pencil line to the centre of the spot.
- Measure the distance from the upfront and the pencil line.
- Rf= distance moved by the chemicalt/distance moved by the solvent,
7
Q
How can we use Rf values to determine a chemical?
A
- Look up the Rf value in a data base to tell us it’s identity.
- Several different chemicals may have the same Rf so repeat the experiment using a different solvent.
- If the chemical is not in the data base;
- There will be no Rfvalue.
- carry out further anylasis.
