Question

a) A zinc strip is dropped into copper sulphate solution (blue coloured) in a beaker. After two hours, the
colour of the solution changes to colourless and a reddish deposit is seen on the zinc strip. (3)
i) Explain why the colour of the solution changes.
ii) Will the reddish deposit be formed if the zinc strip is replaced by a silver strip? Give suitable answer.
b) Which of the following reactions will not occur? Why?
(i) Zinc sulphate + Copper ➝ Copper Sulphate + zinc
(ii) Copper Sulphate + Iron ➝ Iron Sulphate + copper

Answer 1

Answer:

This happens due to displacement reaction where a more reactive metal displaces a less reactive metal

I) as zinc is more reactive than copper that's why in order to displace copper from copper sulphate solution the reaction between the zinc strip and copper sulphate solution I will make the solution as colourless

ii) no reddish deposit will not be formed because silver is less reactive than copper

b) the first reaction will not occur because copper is less reactive than zinc that's why copper cannot displace zinc so the equation should be

zinc sulphate + copper ....gives.... zinc sulphate + copper

the second equation will occur because iron will displace copper