[appelsinbla]

i have two questions:
1. for industrial preparation of HCl, why hydrolysis of PCl3 is used: PCl3+H2O------>H3PO3+HCl. Why can't hydrolysis of PCl5 be done for this purpose: PCl5+H2O-------->POCl3+HCl
2. Low grade copper ore is treated with dilute sulfuric acid to convert ore into copper sulfate solution. From this solution, copper metal is recovered by dipping iron rods in it. How copper forms copper sulphate solution? in a reactivity series, hydrogen is above the copper, so the former is more reactive. Therefore, copper can't produce copper sulfate solution and hence there should be no reaction.

[discodermolide]

First part: a) try balancing your reaction equations.
Perhaps PCl₃ is cheaper? The POCl₃ will also hydrolyse.

[Arkcon]

For number 2, you are correct, hydrogen can't displace copper, given their positions in the electronegativity series.  Copper can't be attacked by HCl, as an example.  Yet it can slowly be attacked by sulfuric acid, if you bubble air or oxygen through.  And copper is rapidly attacked by nitric acid.  You can even dissolve copper in hydrochloric acid if you add hydrogen peroxide.  So something else is happening.  Can you guess what it is, from the examples I've given?