Chemical Changes

Question 1

Titrations

Answer 1

Allow you to find out exactly how much acid is needed to neutralise a quantity of alkali or vice versa

1) use a pipette and pipette filler , add a set volume of alligator to a conical flask. Add a few more drops of indicator too.

2) Use a funnel to fill a buttered with some acid of known concentration. Do this below eye level to avoid spill.

3) use a burette to add the alkali a bit at a time giving the conical flask a regular swirl.

4) The indicator changes colour when all alkali has been neutralised

5) record final volume of acid is in burette use it along with initial reading to calculate the volume of acid used to neutralise the alkali

Question 2

Strong and weak acids

Answer 2

Strong acids ionise completely in water
Weak acids do not fully ionise in a solution

Strong acids are more reactive than weak acids of the same conc because more of the acid particle release H+ ions.

Question 3

Reactions of Acids

Answer 3

Metal oxides and hydroxides form a salt and water

Acid + metal oxide / hydroxide - salt + water

Acids and metal carbonated produce carbon dioxide

Acid + metal carbonate - salt + water + carbon dioxide

Question 4

Reactivity series
Most to least reactive

Answer 4

Potassium
Sodium
Lithium
Calcium
Magnesium
Carbon
Zinc
Iron
Hydrogen
Copper

Question 5

Metals and acids

Answer 5

Acid + metal - salt + hydrogen

Speed of reaction is the rate at which the bubbles of hydrogen are given off. The more reactive the more explosive and violent reaction

Metal + water - metal hydroxide + hydrogen
Potassium , sodium , lithium and calcium react with water

Zinc , iron and copper won’t

Question 6

Redox reactions

Answer 6

When electrons are transferred
- displacement reactions where a more reactive metal will displace a less reactive metal from its compound