AQA 8: Chemical analysis

A substance is ​ (a)   if it is made up of a single element or compound, not ​ (b)   with any other substance. The word 'pure' is also used in an unscientific way to mean ​ (c)   .

The way to test for purity is by measuring ​ (d)   or boiling points, as mixtures ​ (e)   at different temperatures to pure substances.

• chemically pure
• mixed
• unadulterated
• melting
• change state
• safe
• evaporation
• react
• physically perfect

In chromatography, the stationary phase is normally:

• The solvent

• The paper

• The ink

• The beaker

A formulation is a designed mixture with a specific 'recipe' of components and ratios.

Which of these are examples of formulations?

• Fuel, such as E10 petrol

• Medicine such as aspirin

• Alloy such as brass

• Fertiliser such as rose food

• Cleaning agent such as Dettol

In chromatography, the mobile phase is normally:

• The solvent

• The paper

• The ink

• The beaker

In chromatography, the component that will move furthest is the one that is ​ (a)   in the mobile phase. An ​ (b)   substance will not move.

• most soluble
• insoluble
• most reactive
• heaviest
• lightest
• inert
• unreactive

The definition of R_f value in chromatography is;

• Distance moved by solvent / distance moved by substance

• Distance moved by substance / distance moved by solvent

In a flame test, the colours of five metal ions is:

• Li - red

  Na - yellow

  K - lilac

  Ca - orange-red

  Cu - blue-green

• Li - orange

  Na - yellow

  K - lilac

  Ca - orange-red

  Cu - bright green

• Li - red

  Na - blue

  K - lilac

  Ca - dark red

  Cu - blue-green

To test for Hydrogen gas, we use:

• a lighted splint, it will cause a squeak or pop

• damp red litmus paper, it will turn blue

• lime water, it will turn cloudy

• a glowing splint, it will relight

• damp litmus paper, it will be bleached (turn white)

To test for Oxygen gas, we use:

• a lighted splint, it will cause a squeak or pop

• damp red litmus paper, it will turn blue

• lime water, it will turn cloudy

• a glowing splint, it will relight

• damp litmus paper, it will be bleached (turn white)

To test for Carbon dioxide gas, we use:

• a lighted splint, it will cause a squeak or pop

• damp red litmus paper, it will turn blue

• lime water, it will turn cloudy

• a glowing splint, it will relight

• damp litmus paper, it will be bleached (turn white)