Reactivity Series (Cambridge International IGCSE Chemistry)

Spec point — 9.2.1 · State the order of the reactivity series as: potassium, sodium, calcium, magnesium, aluminium, carbon, zinc, iron, hydrogen, copper, silver, gold Describe the reactions, if any, of: potassium, sodium and calcium with cold water magnesium with steam magnesium, zinc, iron, copper, silver and gold with dilute hydrochloric acid and explain these reactions in terms of the position of the metals in the reactivity series Deduce an order of reactivity from a given set of experimental results

Reactivity series

What is the reactivity series of metals?

• The chemistry of the metals is studied by analysing their reactions with water and acids
• Based on these reactions a reactivity series of metals can be produced
• The series can be used to place a group of metals in order of reactivity based on the observations of their reactions with water and acids
• The non-metals hydrogen and carbon are also included in the reactivity series as they are used to extract metals from their oxides

Reactivity series order

• The order of the reactivity series is:

  • Potassium
  • Sodium
  • Calcium
  • Magnesium
  • Aluminium
  • Carbon (non-metal)
  • Zinc
  • Iron
  • Hydrogen (non-metal)
  • Copper
  • Silver
  • Gold

How to remember the reactivity series

• The order of this reactivity series can be memorised using the following mnemonic

  • “Please send cats, monkeys and cute zebras into hot countries signed Gordon"

Reactivity Series Mnemonic

Reaction of metals with cold water

• Potassium, sodium and calcium react with cold water to form a metal hydroxide and hydrogen gas:

metal + water → metal hydroxide + hydrogen

• Potassium

  • Reacts violently with cold water

potassium + water → potassium hydroxide + hydrogen

2K (s) + 2H₂O (l) → 2KOH (aq) + H₂(g)

• Sodium

  • Reacts quickly with cold water

sodium + water → sodium hydroxide + hydrogen

2Na (s) + 2H₂O (l) → 2NaOH (aq) + H₂(g)

• Calcium

  • Reacts less strongly with cold water

calcium + water → calcium hydroxide + hydrogen

Ca (s) + 2H₂O (l) → Ca(OH)₂(aq) + H₂(g)

Reactions of metals with steam

• Magnesium does not react much with cold water but reacts with steam to form a metal oxide and hydrogen gas:

magnesium + steam → magnesium oxide + hydrogen

Mg (s) + H₂O (g) → MgO (s) + H₂(g)

Reaction with dilute hydrochloric acid

• Metals above hydrogen in the reactivity series react with dilute hydrochloric acid

  • The more reactive the metal then the more vigorous the reaction will be
  • Metals that are placed high on the reactivity series such as potassium and sodium are very dangerous and react explosively with acids

• Metals below hydrogen in the reactivity series do not react with dilute hydrochloric acid

• When hydrochloric acid reacts with a metal it forms a salt and hydrogen gas:

metal + acid ⟶ salt + hydrogen

Metals reacting with dilute hydrochloric acid

• Metals that do react with dilute hydrochloric acid include:

1. Magnesium

magnesium + hydrochloric acid → magnesium chloride + hydrogen

Mg (s) + 2HCl (aq) → MgCl₂ (aq) + H₂ (g)

1. Zinc

zinc + hydrochloric acid → zinc chloride + hydrogen

Zn (s) + 2HCl (aq) → ZnCl₂ (aq) + H₂ (g)

1. Iron

iron + hydrochloric acid → iron(II) chloride + hydrogen

Fe (s) + 2HCl (aq) → FeCl₂ (aq) + H₂ (g)

Metals that do not react with dilute hydrochloric acid

• Metals that do not react with dilute hydrochloric acid include:

1. Copper

copper + dilute hydrochloric acid → no reaction

1. Silver

silver + dilute hydrochloric acid → no reaction

1. Gold

gold + dilute hydrochloric acid → no reaction

• The more reactive the metal, the more vigorous the reaction with dilute hydrochloric acid is

Deducing the order of reactivity

• The order of reactivity of metals can be deduced by making experimental observations

  • The more vigorous the reaction, the more reactive the metal

• If two metals both react with water, the more vigorous reaction shows the more reactive metal

• If metals do not react with water, their order can be deduced from their reactions with dilute hydrochloric acid

• Temperature change can also be used

  • The greater the temperature change in a reaction involving a metal, the more reactive the metal is