A container holds a mixture of glass shards and iron filings. What is the best way to separate the glass shards from the iron filings?

Apr 9, 2016

Suppose I were to offer you half a million pounds to separate the mixture. Would you be able to offer a solution?

Explanation:

Now, I think one way of separation by physical means is the obvious way, and I leave it you to come up with it.

A chemical means of separation could exploit the inertness (i.e. the lack of reactivity) of glass. Treat the mixture with concentrated acid (nitric or hydrochloric), and stand back:

$F e \left(s\right) + 2 H C l \left(a q\right) \rightarrow F e C {l}_{2} \left(a q\right) + {H}_{2} \left(g\right) \uparrow$

Filter off the ferrous chloride solution, and the glass is retained. You would have to reduce the filtrate to get back to elemental iron. Would separation by physical means be easier?