Reactivity Series

Question 1

What is the order of reactivity in the metals we need to know?

Answer 1

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

Carbon + hydrogen are included, although non-metals

Question 2

What products form when a metal reacts with water?

Answer 2

A metal hydroxide is formed and hydrogen is released

Question 3

How reactive do metals need to be to react with water?

Answer 3

• Only metals above hydrogen in the reactivity series will react with water, as metals below it cannot displace the hydrogen in water
• This means that any metal iron or above will react
• That being said, noticeable reactions only happen at calcium and higher, and get more and more violent the higher up in the reactivitity series

Question 4

How reactive do metals need to be to react with a dilute acid?

The dilute acids are hydrochloric acid and sulfuric acid

Answer 4

Again, they must be higher than hydrogen as they must be able to displace the hydrogen in the acid

The reactions get more and more violent as you move up the reactivity series - potassium will be explosive, while iron will be slow

Question 5

What products form when a metal reacts with dilute sulfuric acid?

Answer 5

A metal sulphate is formed and hydrogen is released

Question 6

What products form when a metal reacts with dilute hydrochloric acid?

Answer 6

A metal chloride is formed and hydrogen is released

Question 7

What happens when an acid reacts with a metal oxide?

Answer 7

• A salt and water is formed
• For example: hydrochloric acid + magnesium oxide –> magnesium chloride + water

When reacting with a metal carbonate, they form a salt, water and carbon dioxide

Question 8

What happens in a displacement reaction involving a metal and a metal oxide?

Answer 8

• If the metal is more reactive than the metal in the metal oxide, it will displace the metal, forming an oxide of its own and leaving the other metal on its own
• For example, Iron Oxide + Aluminium –> Aluminium Oxide + Iron

If it is not more reactive, nothing will happen

Question 9

What happens in a displacement reaction involving a metal and an aqueous solution of metal salts?

Meaning a sulfate, chloride, nitrate solution ect.

Answer 9

• Similiarily, if the metal is more reactive than the metal in the aqueous solution, it will form the compound of its own metal and leave the other metal on its own
• For example, Iron Sulfate + Magnesium = Magnesium Sulfate + Iron
• These reactions can be easily seen by colour changes of the solution and the metal sitting at the bottom

Question 10

What conditions are necessary for iron to rust?

Answer 10

• There must be water and oxygen present
• Sodium chloride speeds up the reaction, but is not necessary

Question 11

What is the word equation for iron rusting?

Answer 11

Iron + Water + Oxygen –> Hydrated Iron Oxide

Question 12

What are barrier methods and what is the disadvantage?

Answer 12

• Barrier methods are when you coat iron with materials like paint, plastic or oil to stop the iron from coming into contact with water/oxygen
• The disadvantage is that if it gets scratched/washed away the iron will then be exposed

Question 13

What is galvanising/sacrificial protection and how does it work?

Answer 13

• Sacrificial protection is when you coat iron with a metal higher in reactivity to prevent rusting, galvanising is specifically coating it with zinc
• The zinc/metals with higher reactivity protect the iron even if it is partly scratched or washed away as the metal with higher reactivity corrodes easier due to its higher reactivity and more ready loss of electrons

Question 14

What is oxidation?

Answer 14

When a substance loses electrons, usually from gaining oxygen

Question 15

What is a reduction?

Answer 15

When a substance gains electrons, usually from losing oxygen

Question 16

What is a redox reaction?

Answer 16

A reaction where one substance gains electrons, and another loses electrons usually involving oxygen

Important: Oxidation cannot occur without reduction and vice versa, so all reactions involving either are redox reactions

Question 17

What is the oxidising agent?

Answer 17

• The substance that loses oxygen in order to supply it to another substance
• In the redox reaction: Zinc + Copper Oxide –> Zinc Oxide + Copper, copper is the oxidising agent

Question 18

What is the reducing agent?

Answer 18

• The substance that gains oxygen and takes it away from another substance through displacement
• In the redox reaction: Zinc + Copper Oxide –> Zinc Oxide + Copper, zinc is the reducing agent

Question 19

Explain oxidising and reducing in terms of the gain or loss of electrons

Answer 19

• The substance that gets oxidised loses electrons
• The substance that is reduced gains electrons

• You can understand this by thinking about ionic bonding and how the substance that gets oxidised will donate its electrons to oxygen to achieve a full outer shell, and vice versa
• Don’t get confused, the oxidising agent gets reduced, so it gains electrons and the reducing agent gets oxidised, so it loses electrons

Question 20

What kinds of observations might you make when mixing reactive metals with dilute acids?

Answer 20

• Bubbling, gentle or very violent depending on reactivity
• The metal dissolving, the pace at which this happens depending on reactivity
• A squeaky pop when tested for hydrogen, the intensity of which will also depend on reactivity

Question 21

What kinds of observations might you make in a metal displacement reaction?

Answer 21

• Solution colour change
• The more reactive metal dissolving into the solution
• The less reactive metal forming

Not bubbling!