2.15 - 2.20 Loss and gain
Rust forms on iron and steel as a result of a redox reaction between iron and oxygen.
Oxidation and reduction reactions are very commonplace. When a element combines with oxygen that element is said to have been oxidised. When the oxygen is removed from an oxide of an element to leave the element on its own, the oxide is said to have been reduced.
Here we will use broader definition of oxidation and reduction which considers the loss and gain of electrons.
2.15 Activity 1. Displacement
2.15 understand how metals can be arranged in a reactivity series based on their reactions
with: water, dilute hydrochloric or sulfuric acid.
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.
2.17 know the order of reactivity of these metals: potassium, sodium, lithium, calcium,
magnesium, aluminium, zinc, iron, copper, silver, gold
This video explains the reaction when copper metal is displaced from solution by the more reactive metal iron. An iron nail is placed in a solution of copper sulphate.
- which is the more reactive metal
- what metal is displaced from solution?
- which ions are reduced
- explain what is being oxidised in this reaction?
- iron is more reactive than copper
- copper is displaced from the solution by the iron
- copper ions are reduced ( gain electrons) to become copper atoms
- iron atoms are oxidised to iron ions
Iron atoms are more reactive than copper. Iron displaces copper ions from the solution.
A question of reactivity
You can use the reactivity series to predict what will happen when a solid sample of one metal is placed in a solution of another metal
Give and take...
Half equations can be used to show what happens to each type of particle involved:
Video Exercise: Metal displacement reactions close up..
This video shows a number of metal displacement reactions magnified and speeded up. For each reaction in turn:
- decide which metal is oxidised
- decide which metal is reduced
- write two half equations to represent these changes
- use these equations to decide the order of reactivity of lead, silver, copper and zinc