Chemical Analysis

Question 1

What are some separation techniques?

Answer 1

Filtration
Evaporation
Crystallisation
Simple distillation
Fractional distillation
Chromatography

Question 2

What apparatus does a filtration use?

Answer 2

Check notes for diagram.

Filter paper
Filter funnel
Clamp
Beaker
Tile

Question 3

What does a filtration separate?

Answer 3

Insoluble substance from liquid.

Question 4

What apparatus does evaporation use?

Answer 4

Check notes for diagram

Evaporating basin
Gauze
Bunsen burner
Tripod
Heatproof mat

Question 5

What is evaporation used to separate?

Answer 5

Separates a solute from a solvent e.g. salt from salt water.

Question 6

What apparatus does simple distillation use?

Answer 6

Check notes for diagram

Borrorned flask
Lietig condenser
Tripod stand
Wire gauze
Bunsen burner
Beaker

Question 7

What is simple distillation used to separate?

Answer 7

Solvent from a solution

Question 8

What is the substance collected from a distillation called?

Answer 8

distillate

Question 9

What apparatus does fractional distillation use? (lab method)

Answer 9

Bunsen burner
Flask
Fractioning column
Thermometer
Condenser
Beaker

Question 10

What is fractional distillation used to separate?

Answer 10

2 or more miscible liquids.

Question 11

What apparatus does chromatography use?

Answer 11

Filter paper
Pencil
Beaker
Solvent

Question 12

What is chromatography used to separate?

Answer 12

2 or more substances in a solution

Question 13

What is the mobile phase in chromatography?

Answer 13

Phase that moves.

Question 14

How do you calculate Rf?

Answer 14

Distance moved by sample
—————————————
Distance moved by solvent

Question 15

What is potable water?

Answer 15

Water safe to drink

Question 16

What is desalination?

Answer 16

The process of removing dissolved substances from sea water.

Question 17

What is the test for water?

Answer 17

Add to anhydrous copper(II) sulfate crystals

Changes white to blue

Question 18

What is a precipitate?

Answer 18

A solid which may be formed in mixing two solutions.

Question 19

What is the test for chlorine?

Answer 19

Turns universal indicator paper red then white

Question 20

How do you test for cations?

Answer 20

Add approximately 5 cm3 of the solution to be tested to a test-tube.
Add sodium hydroxide solution slowly drop wise.
Note your observations in the table.
Continue adding sodium hydroxide drop wise to any precipitates until a large excess is present (about 2/3 full).
Stopper and shake the test tube thoroughly.
Note your observations

Question 21

How do the melting and boiling points of pure substances and mixtures differ?

Answer 21

Pure substances give a sharp boiling and melting point.

Impure substances give boiling and melting points over a range, as the different substances they contain have different points.

The greater the amount of an impurity the greater the difference from the true melting/boiling point and the higher the range.

Question 22

How does the presence of an impurity affect the melting/ boiling point of a solid vs Liquid?

Answer 22

Lowers point of solid.
Raises point of liquid.