Chemistry, asked by Rakeshmiddha, 1 year ago

(a) Distinguish between ‘roasting’ and ‘calcination’. Which of these two is used for sulphide ores and why? (b) Write a chemical equation to illustrate the use of aluminium for joining cracked railway lines. (c) Name the anode, the cathode and the electrolyte used in the electrolytic refining of impure copper.

Answers

Answered by writersparadise
157

(a)    Roasting is a process in which the ores are heated to a temperature that is below its melting point. This happens in the presence of air in order to oxidize the impurities. They are usually removed as gaseous oxides.

 

Calcination is a process in which the ores are heated below its melting point in the absence of air. Volatile impurities like arsenic are removed by this process.

 

Roasting is the method used for sulphide ores. Roasting is used because it is easier to purify the oxides of a substance than the other ores. Therefore, sulphide ores are also heated strongly in the presence of excess oxygen to form its oxides.

 

(b)   The example of equation illustrating the use of aluminum for joining cracked railway lines is depicted in the image.


(c)    In the electrolytic refining of impure copper,

The anode used is – impure copper

The cathode used is – pure copper sheet

The electrolyte used is – a bath of copper sulphate (CuSO4) and sulphuric acid (H2SO4).

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Answered by myrakincsem
104
Thanks for the question.
Calcination is done in the absence of air to heat the ores below their melting point.
While roasting also the process of heating the ores but it is done in the presence of air.

Roasting is used to Sulphide ores because through it the purification of oxides of the substance is easy than the ores.

b) 2Al + Fe203 → Al2o3 + Fe

Also for the electro lytic refining of impure copper , the anode is used as the impure copper sheet while pure copper sheet act as cathode.

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