chemical analysis

Question 1

What is a formation?

Answer 1

A substance with a specific use and therefore a specific recipe

Question 2

State the method and positive result of the test for oxygen:

Answer 2

Method: Glowing splint
Positive result: Re-lit splint

Question 3

State the method and positive result of the test for Hydrogen:

Answer 3

Method: Lit splint
Positive result: Squeaky pop

Question 4

State the method and positive result of the test for Carbon dioxide:

Answer 4

Method: Bubble gas through lime water
Positive result: colourless -> cloudy

Question 5

State the method and positive result of the test for Chlorine:

Answer 5

Method: Damp blue litmus paper
Positive result: Bleaches litmus paper

Question 6

Within chromatography, what is the stationary phase?

Answer 6

The chromatography paper

Question 7

Soluble substances are ____ ______ to the stationary phase.

Answer 7

not carried

Question 8

Soluble substances are not __________\____________ for long in the mobile phase.

Answer 8

carried/ attracted

Question 9

Definition of pure sample:

Answer 9

Only 1 ink spot

Question 10

Impure sample means?

Answer 10

More than 1 one ink spot

Question 11

What is the Rf calculation?

Answer 11

distance of the ink spot
_________________________

distance of solvent

Question 12

Which part of the ink spot should you measure to?

Answer 12

Half way/ the middle

Question 13

In chromatography, all measurements should start at the _______ ______.

Answer 13

Base line

Question 14

State the 6 steps of the chromatography required practical:

Answer 14

1. Draw base line ( pencil and ruler ) above the bottom of the Chromatography paper
2. Add sample of ink onto baseline
3. Lower paper into solvent so the solvent is touching the paper but lower than the base line
4. Put a lid on to prevent solvent evaporation
5. Let the solvent run up the paper
6. Rf calculation ( measure baseline to centre of spot + measure baseline to the solvent front )

Question 15

Why should ink never be used to draw the base line?

Answer 15

It will run up the chromatography paper and distort the results of the investigation.

Question 16

Give 3 examples of a formulation:

Answer 16

fuels, paints and fertilisers

Question 17

Rf values travel from __ to __

Answer 17

0 and 1

Question 18

Measurements in ______________ will give more precise Rf values

Answer 18

millimetres

Question 19

Give a hazard of chromatography:

Answer 19

Hazard: Harmful solvent
Possible harm: Skin irritation
Possible precaution: Avoid skin contact e.g wear gloves