Question

Q1. A student precipitates her ions out of solution, then places it in a hot water bath. After removing it from the water bath, the white precipitate disappeared. At this point, what can you conclude about the ions in her unknown?

1)	mercury may not be present
2)	ammonia, silver and mercury may not be present
3)	silver and mercury may not be present
4)	silver may not be present

Q2.A student with an unknown code of Q7B conducts a qualitative analysis of her unknown and her results indicated the formation of a white precipitate when 6M HCl was added, a yellow precipitate and a grey precipitate. From her results, what ions can you confirm were in her unknown sample?

1)	lead, silver and mercury
2)	lead and mercury
3)	lead and silver
4)	not enough info is given

Answer 1

Q1) In presence of hot water bath,because of the more solubity in water,lead chloride dissolve in water and silver and mercury chloride don't..so white precipitate of lead chloride disappears..so from this conclusion we can say that 3)Silver and Mercury may not be present..

Q2) Here option 4) is right, I.e; not enough info is given..In presence of 6(M) HCl mercury chloride,lead chloride and silver chloride obtained.and all of these compound are white in colour..Then upon treatment with aqueous potassium chromate,yellow precipitate of lead chromate observed.and in presence of aqueous Ammonia,grey precipate of occurs in case of mercury..and lead chloride dissolves..