Question

How could you seperate a solid mixture of silicon dioxide, sodium chloride, iron and calcium carbonate in lab?

Answer 1

Solution:-

First extract with water; it will dissolve the sodium chloride. Then react the remaining two components with dillute hydrochloric acid, it will react only with the calcium carbonate to form soluble calcium chloride (with loss of CO2 gas). Extract with water again to dissolve the calcium chloride, the silicon dioxide will not dissolve under these conditions.

One way of separating CaCO3 from SiO2 is to dissolve the CaCO3 in acid (just not HF acid) then you would be able to filter away the SiO2 and you would then have them separated. The issue with this is that by dissolving in acid you would then have an acidic solution of Ca^+2 ion and not the CaCO3, but it would be very separated for the SiO2.