Chapter 15: The Reactivity Series

Metals in the reactivity series (**most** reactive → **least** reactive)

potassium, sodium, calcium, magnesium, zinc, iron, lead, copper, silver

Reaction of **potassium** with cold water (observation + chem eqn)

reacts very violently with cold water to form potassium hydroxide and hydrogen gas

2K + 2H2O → 2KOH + H2O

Reaction of **sodium** with cold water (observation + chem eqn)

reacts violently with cold water to form sodium hydroxide and hydrogen gas

2Na + 2H2O → 2NaOH + H2O

Reaction of **calcium** with cold water (observation + chem eqn)

reacts readily with cold water to form calcium hydroxide and hydrogen gas,

Ca + 2H2O → Ca(OH)2 + H2O

Reaction of magnesium with cold water (observation + chem eqn)

reacts very slowly with cold water to form magnesium hydroxide and hydrogen gas

Mg + 2H2O → Mg(OH)2 + H2

Metals that do not react with cold water

zinc, iron, lead, copper, silver

Reaction of potassium, sodium and calcium with steam

react explosively

should not be carried out in laboratory

Reaction of hot magnesium with steam (observation + chem eqn)

reacts violently with steam to form magnesium oxide and hydrogen gas

bright white glow produced during reaction

Mg + H2O → MgO + H2

Reaction of hot zinc with steam (observation + chem eqn)

reacts readily with steam to produce zinc oxide and hydrogen

zinc oxide is yellow when hot and white when cold

Zn + H2O → ZnO + H2

Rreaction of red-hot iron with steam (observation + chem eqn)

reacts slowly with steam

iron must be constantly heated for the reaction to progress

3Fe + 4H2O → Fe3O4 + 4H2

Metals that do not react with steam

lead, copper, silver

Reaction of potassium with dilute hydrochloric acid (observation + chem eqn)

reacts explosively to give hydrogen gas

2K + 1HCl → 2KCl + H2

Reaction of sodium with dilute hydrochloric acid (observation + chem eqn)

reacts explosively to give hydrogen gas

2Na + 2HCl → 2NaCl + H2

Reaction of calcium with dilute hydrochloric acid (observation + chem eqn)

reacts violently to give hydrogen gas

Ca + 2HCl → CaCl2 + H2

Reaction of magnesium with dilute hydrochloric acid (observation + chem eqn)

reacts rapidly to give hydrogen gas

Mg + 2HCl → MgCl2 + H2

Reaction of zinc with dilute hydrochloric acid (observation + chem eqn)

reacts moderately fast to give hydrogen gas

Zn + 2HCl → ZnCl2 + H2

Reaction of iron with dilute hydrochloric acid?

reacts slowly to give hydrogen gas

Fe + 2HCl → FeCl2 + H2

Reaction of lead, copper and silver with dilute hydrochloric acid

no reaction occurs

Two agents are used to reduce metals

carbon and hydrogen

Metals that can be reduced by carbon

zinc, iron, lead, copper, silver

Metals that can be reduced by hydrogen?

iron, lead, copper, silver

Relationship between reactivity of metal and its tendency to form positive ions

the more reactive a metal, the greater the tendency to form positive ions

Metal displacement reactions?

Redox reactions

Metal carbonates are unaffected by heat

potassium carbonate, sodium carbonate

Metal carbonates that decompose into a metal oxide and carbon dioxide on heating

calcium carbonate, magnesium carbonate, zinc carbonate, iron(II) carbonate, iron (III) carbonate, copper (II) carbonate

When silver carbonate is strongly heated, it ______

decomposes into silver and carbon dioxide on heating

Two methods of extracting metals from their ores?

reducing metal compound to the metal using carbon, electrolysis

Metals which can only be reduced with electrolysis?

potassium, sodium, calcium, magnesium

Metals which can be reduced by carbon

zinc, iron, lead, copper, silver

General equation for reducing metal oxides with carbon

metal oxide + carbon —heat—> metal + carbon dioxide

Trends of reducing metal oxides with carbon

the lower the metal in the reactivity series from carbon, the more readily the reduction of the metal oxide will occur

oxides of zinc require the highest temp for reduction

General equation for reducing metal oxides with hydrogen

metal oxide + hydrogen → metal + stream

Trends of reducing metal oxides with carbon

oxides of iron require the highest temp for reduction

Conditions needed for rusting

the presence of oxygen in air and water

Some ways used to prevent rusting

protective layer, sacrificial metal

5 types of protective layers

painting, oiling/greasing, plastic coating, tin-plating, chrome-plating

Use of painting and its drawbacks

used for large objects like cars, ships and bridges

if paint on object is scratched, rusting will take place under painted surface

Use of iling/greasing and its drawbacks

used for machinery like tools and machine parts

protective layer of oil/grease gathers dust and must be renewed

Use of coating with plastic and its drawbacks

used for smaller objects like kitchenware

iron starts to rust if plastic layer is torn

Use of tin-plating and its drawbacks?

food cans

iron starts to rust if tin layer is scratched

Uses of chrome-plating for and its advantages

taps, kettles, bicycle handle bars, gives a bright shiny finish and rust protection

Sacrificial protection is ___________

using a more reactive metal to protect iron and steel against rusting

Two methods of sacrificial protection

galvanising with zinc

attaching a more reactive metal like zinc and magnesium

Use of galvanising for and its advantage

water buckets, dustbins, “zinc” roofs, kitchen sinks

metal does not rust even if zinc layer is scratched

Use of attaching metal blocks of zinc/magnesium and its advantage

underground pipes, ships, columns of steel piers

zinc and magnesium corrode in place of iron