1(b) Elements, Compounds, Mixtures

Question 1

Element

Answer 1

Contains 1 type of atom

Question 2

Compound

Answer 2

2 or elements chemically bonded together
Elements combined in fixed ratios

Question 3

Mixture

Answer 3

Various substances mixed together
Made up of elements and/or compounds

Question 4

Separation Techniques

Answer 4

• Filtration
• Crystallisation
• Simple Distillation
• Fractional Distillation
• Paper Chromatography

Question 5

Filtration

Answer 5

To separate a solid from a liquid

Question 6

Crystallisation

Answer 6

To separate solute from a solution

Question 7

Crystallisation Method

Answer 7

1. Heat solution until reduced by half or saturated (test with glass rod - dip into solution and if crystals form quickly)
2. Remove heat and allow crystals to form
3. Remove crystals through filtration

Question 8

Simple Distillation

Answer 8

To separate components on a solution

Question 9

Fractional Distillation

Answer 9

To separate a mixture of liquids (miscible)
Separation using boiling points

Question 10

Paper Chromatography

Answer 10

To separate coloured inks/food colourings

Question 11

Paper Chromatography Method

Answer 11

1. Draw a pencil line from the bottom of the chromatography paper
2. Put samples of dye on pencil line
3. Put into beaker containing solvent and the solvent shouldn’t touch the pencil line (so that samples don’t dissolve)
4. Put lid on top to stop evaporation of solvent from paper.
5. Mark solvent front when solvent reaches 1cm from the top

Question 12

Rf value

Answer 12

Retardation factor

Question 13

Rf value formula

Answer 13

Distance moved by spot/distance moved by solvent front