Two chemists discovered a goldmine. They took a sample and discovered that besides gold, the sample contained four other impurities listed below. How can these scientists seperate their gold from the sample?
Au - nonmagnetic, H20-insoluble, melting point (500 Celsius)
Silica - solid. highly impure, nonmagnetic, melting point (900 celsius)
MgCl2 - H20-soluble, crystal, nonmagnetic
Fe - highly magnetic, H20-insoluble
FeSO4 - solid, nonmagnetic, highly electrostatic
They can separate their gold from the sample in a following way:
1. Separate Fe by a magnet; 2. Separate MgCl2 by water flushing; 3. Separate FeSO4 by electrostatic action; 4. Separate gold from silica by heating the sample to a temperature 500 Celsius until the gold melt.