inorganic chemistry - reactivity series

Question 1

how can order of reactivity be determined based on reactivity with water and dilute hydrochloric acid

Answer 1

hydrochloric acid can be added to metal to test its reactivity. the faster the bubbles are produced, the more reactive it is.

water can also be used for this experiment, but most metals are too low in the reactivity series to react with water

Question 2

displacement reactions between metals, metal oxides, aqueous solutions and salts.

Answer 2

a more reactive metal will displace a less reactive metal from its oxide.
e.g. magnesium + copper oxide –> magnesium oxide + copper

a more reactive metal will displace a less reactive metal from its salt
e.g. zinc + copper sulphate –> zinc sulphate + copper

Question 3

order of reactivity series

Answer 3

Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Hydrogen
Copper
Silver
Gold

Question 4

conditions for iron to rust

Answer 4

oxygen and water must be present

Question 5

reaction for rust

Answer 5

iron + oxygen + water –> hydrated iron (III) oxide

4Fe +3O2 + nH2O –> 2F2e2H2O

Question 6

3 methods to prevent rust

Answer 6

1. galvanising
2. barrier method
3. sacrificial protection

Question 6

how does galvanising work

Answer 6

• coating in zinc. it prevents water and oxygen getting to the iron.
• even if the barrier is broken the more reactive zinc corrodes before the less reactive iron.
• during the process, the zinc loses electrons to form zinc ions.

Question 6

how does barrier method work

Answer 6

rusting may be prevented by stopping the water and oxygen getting to the iron with a barrier of grease, oil, paint or plastic.

Question 7

how does sacrificial protection work

Answer 7

• zinc blocks are attached to iron boat hulls to act as sacrificial anodes.
• zinc is more reactive than iron, so oxygen in the air reacts with the zinc to form a layer of zinc oxide instead of the iron.

Question 8

what is oxidation

Answer 8

• the loss of electrons
• the gain of oxygen

Question 9

what is reduction

Answer 9

• gain of electrons
• loss of oxygen

Question 10

what is redox

Answer 10

a reaction involving oxidation and reduction

Question 11

what is an oxidising agent

Answer 11

a substance that gives oxygen or removes electrons (it is itself reduced).

Question 12

what is a reducing agent

Answer 12

a substance that takes oxygen or gives electrons (it is itself oxidised).

Question 13

experiment for reaction between dilute hydrochloric and sulfuric acids and metals

Answer 13

metal + acid –> salt + hydrogen
e.g. magnesium + hydrochloric acid –> magnesium chloride + hydrogen

this is a displacement reaction

Question 14

3 things that happen in a displacement reaction

Answer 14

• rapid fizzing
• mixture becomes warm as heat is produced (exothermic).
• magnesium disappears to leave a colourless solution of magnesium chloride