chem[15分]

1.
(a)
Pure sulphuric acid consists of only molecules of sulphuric acid. It cannot conduct electricity because thereare neither mobile ions nor delocalized electrons to conduct electricity.

In dilute sulphuric acid, the sulphuric acid molecules are ionized to give hydrogenions and sulphate ions. It can conductelectricity by mobile hydrogen ions and mobile sulphate ions.
H2SO4(aq) → 2H^+(aq) + SO4^2-(aq)


(b)
Concentrated sulphuric acid has the property of absorbing moisture, and thus itcan be used as a drying gas to absorb the moisture mixed with gas.

Concentrated sulphuric acid can be used to dry sulphur dioxide because concentratedsulphuric acid can absorb moisture in the sulphur dioxide gas but does notreact with sulphur dioxide.

Concentrated sulphuric acid cannot be used to dry ammonia because they canundergo neutralization to give ammonium sulphate as sulphuric acid is acidicwhile ammonia is basic.
H2SO4 + NH3 → (NH4)2SO4


(c)
Hot concentrated sulphuric acid is an oxidizing agent, while copper is areducing agent. They can undergo redoxreaction to give sulphur dioxide gas.
Cu + 2H2SO4 →CuSO4 + 2H2O + SO2

Dilute sulphuric acid does not have oxidizing powder, and thus it cannot undergoredox reaction with copper. Besides,copper is a very unreactive metal which cannot reaction with dilute acid.


(d)
Hot concentrated sulphuric acid is a dehydrating agent, which can remove waterfrom blue crystals of copper(II) sulphate-5-water to give white powder ofanhydrous copper(II) sulphate.
CuSO4•5H2O →CuSO4 + 5H2O