Question

How are the following separated ?
Lead sulphate from a mixture of lead sulphate and lead chloride ?
a.) distillation
b.) filtration
c.) chromatography
d.) evaporation

Answer 1

Hint: The lead sulphate is insoluble in water while the lead chloride is soluble in water. Thus, dissolving the mixture in water and by use of correct separation technique which could differentiate between a solid and a liquid could be used. The technique that requires both the components to be soluble to separate can not be used.

Complete step by step answer:
We have studied that lead sulphate is insoluble in water. This means if we try to dissolve it in water, it will not form a clear mixture. But the lead chloride is soluble in water and when we put lead chloride in water, it gets completely dissolved and thereby gives a clear solution.

So, if we dissolve the mixture in water. The lead chloride will get dissolved while the lead sulphate will remain as solid in the solution. After this, by using a certain technique we can separate these.
Now, let us see the techniques given to us and then we can easily guess the right answer.
The first technique given is using distillation. It is the process of boiling the liquid and immediately condensing it to get a specific component which got boiled at that point. This technique can not be used because both the salts do not get dissolved.

The second technique given is filtration. It is possible. As we have dissolved the mixture in water, the lead sulphate is present as solid. This can be filtered and we get solid lead sulphate on filter paper as precipitate while the solution will be down. So, the option b.) is the possible answer.

Now, comes the third option chromatography. Chromatography requires the separation of mixtures which are dissolved completely. So, it can not be used.
The last and fourth option is evaporation. This could also be used. If we dissolve the mixture and then evaporate it. The lead chloride will form vapours and go while the solid lead sulphate will remain in the beaker. So, even this option is correct.
So, the correct answer is “Option B and D”.

Note: It must be noted that during filtration, it could be normal. But it is always better to use Whatman filter paper. Further, if one uses vacuum filtration, then the solid will be better filtered. Further, during evaporation, one should take care not to give excessive heat. The excess heat after the solution has vaporised could burn the lead sulphate.