7 min readConcept sheetSection A MCQ (1 mark) and fill in the blank (2 marks, two parts); Section B very short answer (2 marks) on a displacement reaction

The reactivity series and displacement

The reactivity series arranges metals from the most to the least reactive. A more reactive metal displaces a less reactive metal from its salt solution.

Reactivity (activity) seriesK > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Hg > Ag > Au; also called the electrochemical series

DisplacementA more reactive metal pushes a less reactive metal out of its salt solution: Fe + CuSO₄ → FeSO₄ + Cu

Above hydrogenMetals above H give hydrogen with dilute acids; Cu, Hg, Ag and Au do not

The reactivity series in your NIOS lesson

Order	Element	Symbol
1 (most reactive)	Potassium	K
2	Sodium	Na
3	Calcium	Ca
4	Magnesium	Mg
5	Aluminium	Al
6	Zinc	Zn
7	Iron	Fe
8	Lead	Pb
Marker	Hydrogen (not a metal)	H
9	Copper	Cu
10	Mercury	Hg
11	Silver	Ag
12 (least reactive)	Gold	Au

Building the series from displacement

1
Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s)
An iron nail in blue copper sulphate gets a brown coat of copper, and the solution turns pale green. So Fe is above Cu
2
Cu(s) + 2AgNO₃(aq) → Cu(NO₃)₂(aq) + 2Ag(s)
A copper wire in silver nitrate gets a shiny grey coat of silver, and the solution turns blue. So Cu is above Ag
3
Ag(s) + CuSO₄(aq) → no reaction
Silver is less reactive than copper, so it cannot displace it
4
Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s)
Zinc is above copper, so it displaces copper
5★
The rule
A metal displaces any metal below it from a solution of its salt

★ key step

Using the series

Metals above hydrogen give hydrogen with dilute acids. The higher the metal, the faster the reaction.
Metals below hydrogen (Cu, Hg, Ag, Au) give no hydrogen with dilute acids.
The top metals (K, Na, Ca, Mg, Al) are never found free in nature. The bottom ones (Ag, Au) are often found free.
Never store copper sulphate solution in an iron vessel: iron displaces the copper, and the vessel slowly gets a hole.
The series also decides how a metal is extracted from its ore (see the next topic).

Activity: test it yourself

1
Clean an iron nail and two copper wires with sandpaper.
2
Dip the nail in copper sulphate solution and one copper wire in dilute silver nitrate solution. Leave them for about 20 minutes.
3
Observe.
Brown copper forms on the nail and the blue solution turns pale green. Grey silver forms on the copper wire and that solution turns blue
4★
Now dip the second copper wire in iron sulphate solution.
No change: copper cannot displace iron

★ key step

In real life

Farmers mix copper sulphate sprays for crops in plastic or wooden containers, not iron buckets, because iron would displace the copper. Gold jewellery stays bright for generations because gold is at the bottom of the series.

Exam angle

2 marks: “What would you see if an iron nail is left in copper sulphate solution for some time? Write the equation.” A brown coat of copper forms on the nail, and the blue solution turns pale green. Fe + CuSO₄ → FeSO₄ + Cu, because iron is more reactive than copper.

2 marks: “Why is there no reaction when a silver wire is placed in copper sulphate solution?” Silver is below copper in the reactivity series. Being less reactive, it cannot displace copper from its salt.

1 marks: “Which is the most reactive metal: zinc, iron, copper or magnesium?” Magnesium.

Remember it

Please Send Cats, Monkeys And Zebras In Large Herds, Carefully Minding Silly Giraffes: K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Hg, Ag, Au.