c8: chemical analysis

what are pure substances?

a single element or compound, not mixed with any other substances

how to distinguish pure substances from mixtures?

pure elements and compounds melt and boil at specific temperatures, so melting and boiling point data can be used.

what is a formulation?

a mixture that has been designed as a useful product

how are formulations made?

by mixing the components in carefully measured quantities in carefully measure quantities to ensure that the product has required properties.

state some formulations.

1. fuels

2. cleaning agents

3. paints

4. medicines

5. alloys

6. fertilisers

7. foods

how is chromatography used?

to separate mixtures and can give information to help identify substances

what does seperation depend on?

the distribution of substance between the phases

what is the test for hydrogen?

uses a burning splint held at the open end of a test tube of the gas. hydrogen burns rapidly with a pop sound

what is the test for oxygen?

uses a glowing splint into a test tube of the gas. the splint relights in oxygen

what is the test for carbon dioxide?

uses lime water. when carbon dioxide is shaken into or bubbled through limewater it turns milky

what is the test for chlorine?

uses litmus paper. when damp litmus paper is put into chlorine gas the litmus paper is bleached and turns white

what are the flame test results?

1. lithium→crimson flame

2. sodium → yellow flame

3. potassium → lilac flame

4. calcium → orange red flame

5. copper → green flame

what are the sodium hydroxide test results?

1. aluminium → white

2. calcium → white

3. magnesium → white

4. copper → blue

5. iron (II) → green

6. iron (II) → brown

only aluminium hydroxide precipitate dissolves in excess sodium hydroxide

what are the results of the silver nitrate solution?

1. silver chloride is white

2. silver bromide is cream

3. silver iodide is yellow

what are the properties of instrumental methods?

accurate, sensitive and rapid