Chemistry
Thin strips of magnesium, copper and iron are taken.
(a) Write down what happens when these metals are treated as follows
(i) Heated in presence of air
(ii) Heated with dil. HCl
(iii) Added to an aqueous solution of zinc sulphate
(b) Arrange these metals in descending order of reactivity.
Answer
(a) (i) When we heat magnesium, copper and iron in presence of air they form respective oxides.
(ii) Magnesium and iron react with HCl liberating hydrogen and forming their respective salts.
Mg + 2HCl ⟶ MgCl2 + H2 ↑
Fe + 2HCl ⟶ FeCl2 + H2 ↑
As Cu is below hydrogen in metal reactivity series, hence, it cannot displace hydrogen from acid and so no reaction takes place.
Cu + HCl (dil) ⟶ no reaction
(iii) Magnesium will displace zinc from zinc sulphate solution as magnesium is more reactive than zinc and is placed above zinc in the reactivity series of metals.
Mg + ZnSO4 ⟶ MgSO4 + Zn
Copper and iron are less reactive and are placed below zinc in the reactivity series, hence will not displace it and no reaction will take place.
(b) Mg > Fe > Cu
Related Questions
Give equations to express the reaction between:
(a) steam and red hot iron
(b) calcium and water
Which metal produces hydrogen gas on reaction with cold water?
- Al
- Fe
- Pd
- Na
A small piece of calcium metal is put into a small trough containing water. There is effervescence and white turbidity is formed.
(a) Name the gas formed in the reaction. How would you test the gas?
(b) Write an equation for the reaction.
(c) What do you observe when a few drops of red litmus solution are added to the turbid solution?
Hydrogen is evolved by the action of cold dil. HNO3 on
- Fe
- Cu
- Mg
- Zn