Air is a mixture of different gases.
The abundance of gases in the air is as follows:
2:14 Practical: determine the approximate percentage by volume of oxygen in air using a metal or a non-metal
The following 3 experiments can be used to determine that oxygen (O2) makes up approximately 20% by volume of air.
The copper is in excess and uses up the oxygen to form copper oxide (CuO).
All the oxygen in the air is therefore used up, and so the volume of the air decreases by about 20% (the percentage of oxygen in air).
The iron reacts with the oxygen in the air (rusting).
As long as the iron, oxygen and water are all in excess, the total volume of air enclosed by the apparatus decreases by about a fifth (20%) over several days.
The phosphorus is lit with a hot wire.
It reacts with the oxygen in the air and causes the water level in the bell jar to rise by about 20%.
2:15 understand how metals can be arranged in a reactivity series based on their reactions with: water and dilute hydrochloric or sulfuric acid
Some metals are more reactive than others.
The order of reactivity can be determined by adding acid to different metals and observing the rate of reaction.
For example, when hydrochloric acid is added to iron (Fe) then bubbles of hydrogen are produced slowly. However, if the same acid is added to zinc (Zn) then bubbles will be produced more quickly. This tells us that zinc is more reactive than iron.
Instead of using acid, water can be used to test the relative reactivity of metals. However, many metals are too low in the reactivity series to react with water
2:16 understand how metals can be arranged in a reactivity series based on their displacement reactions between: metals and metal oxides, metals and aqueous solutions of metal salts
A metal will displace another metal from its oxide that is lower in the reactivity series. For example, a reaction with magnesium and copper (II) oxide will result in the magnesium displacing the copper from its oxide:
A metal will also displace another metal from its salt that is lower in the reactivity series. For example, the reaction between zinc and copper (II) sulfate solution will result in zinc displacing the copper from its salt:
The blue colour of the copper (II) sulfate solution fades as colourless zinc sulfate solution is formed.
2:17 know the order of reactivity of these metals: potassium, sodium, lithium, calcium, magnesium, aluminium, zinc, iron, copper, silver, gold
A more reactive metal will displace a less reactive metal.
In addition a more reactive metal will react more vigorously than a less reactive metal.
For example, potassium takes a shorter time to react than sodium:
Iron rusts when oxygen and water are present.