C2 - Experimental techniques

Question 1

What is a solvent

Answer 1

A liquid in which a solid dissolves

Question 2

What is a solute

Answer 2

dissolved solid

Question 3

What is the use of filtration

Answer 3

Separate mixtures of insoluble solids and liquids and to purify impure solids

Question 4

Steps and apparatus for filtration

Answer 4

Apparatus: Funnel, filter paper, glass rod, beaker, stand and mixture.
Steps: Pour the beaker of mixture into the funnel
The liquid will filter from the solid and be collected in a beaker.
The insoluble solid trapped at the top is called residue

Question 5

What is crystallization used for

Answer 5

to separate mixtures of solid dissolved in liquid

Question 6

Steps and apparatus for crystallization

Answer 6

Apparatus: Tripod, bunsen burner, heat proof mat, mixture, evaporating basin.
Steps: The heat mixture so the solvent evaporates
crystals of dissolved solute will form

Question 7

What is distillation used for

Answer 7

to separate a mixture of liquids by using their different boiling points

Question 8

apparatus and steps for simple distillation

Answer 8

ApparatusTemperature stick, bong, flask, solution, tripod, bunsen burner, heatproof mat, liebig condenser and beaker.

Steps: Mixture is heated until the liquid with lowest boiling point boils. The vapor is collected then condensed on the cold surface of the condenser and then the gas turns back to liquid to be collected in the beaker.

Question 9

What is fractional distillation

Answer 9

when liquids being distilled have similar boiling points and a fractionating column is used to produce a large surface area for condensation meaning more purer fractions.

Question 10

What are the methods of purification

Answer 10

distillation and filtration

Question 11

Difference between fractional and simple distillation

Answer 11

simple distillation is separating mixture of liquids with a relatively big gap of temperatures. Fractional distillation is used when liquids have similar boiling points which simple distillation cannot separate them completely.

Question 12

Different apparatus used for different measurements

Answer 12

Time: Stopwatch
Temperature: thermometer
Mass: Balance or scale
Volume of liquids: burettes, pipettes and measuring cylinders

Question 13

Why is paper chromatography used

Answer 13

separate solutions or liquids that are mixed together

Question 14

How to carry out a paper chromatography experiment

Answer 14

Apparatus: Water, ink, a piece of paper, beaker, pencil and splint

Steps: Mark the black ink with a X.
As the water rises up the paper the different dyes travel different distances

Question 15

What is retention factors in chromatography

Answer 15

it compares the distance a substance has travelled up a filter paper with the distance travelled by the solvent

Question 16

formula for retention factor (Rf)

Answer 16

distance moved by a substance from the baseline / Distance moved by the solvent from the baseline

Question 17

What is the solvent front

Answer 17

height reached by solvent

Question 18

How to check purity of solids and liquids

Answer 18

using heat to find the temperature at which they melt or boil at.
An impure solid will have a lower melting point than a pure solid
A liquid containing a dissolved solid will have a higher boiling point than pure

Question 19

Which technique is used for the following

1. Mixture of insoluble solid and liquid
2. Mixture of soluble solid and liquid (solution)
3. Mixture of liquids
4. Mixture of dissolved solids

Answer 19

1. filtration
2. crystallization
3. simple and fractional distillation
4. chromotography