Question

G] What do you observe when :- [5]
i) When chlorine is passed through the solution of KI.
ii) Iron nails are added to copper sulphate solution.
iii) Blue copper sulphate crystals are heated.
iv) Carbon dioxide is passed through lime water.
v) Reaction between HCl and NH3.

Answer 1

Explanation:

i) When chlorine (Cl2) gas is passed through an aqueous solution of potassium

iodide (KI), the products formed are solid iodine (I2) and potassium chloride (KCl). This is a displacement reaction in which the less reactive iodine in potassium iodide is displaced by the more reactive chlorine.

ii)

When an iron nail is dipped in copper sulphate solution, a brown coating of copper is formed on the surface of iron and the colour of copper sulphate solution changes from blue to light green.

iii)The blue coloured copper sulphate crystals turns white due to the loss of water molecules. The formula of copper sulphate is CuSO4. 5H2O. When copper sulphate is heated, it looses water molecules and hence it looses blue colour.

iv)CO2, that is, Carbon Dioxide reacts with Ca(OH)2 , that is, lime water, to form a white precipitate of CaCO3, Calcium Carbonate. Adding more carbon dioxide results in the precipitate dissolving to form a colourless solution of calcium hydrogencarbonate.

v) In water, the reaction between ammonia (NH3) and hydrogen chloride (HCl) is a textbook example of acid-base chemistry. By its chemical nature, the nitrogen in ammonia prefers to be attached to four hydrogens rather than the mere three it has, so it steals the hydrogen from hydrogen chloride.