Question

Can the rusting of iron nails occur in distill water? Justify your answer.

Answer 1

Hint: Distill water is water which is free of minerals and not oxygen. Rusting of iron is a process which in iron undergoes oxidation to form iron oxide.

Complete step by step answer:
Rusting of iron is also termed as corrosion. Corrosion is a natural process by which metals are coated with oxides of metals. The formation of oxides occurs through an oxidation step. The metal loses electrons to the oxygen in the atmosphere and forms metal oxide.
The rusting of iron is thus a redox reaction. The two half reactions and the overall reaction are written as:
Reaction at Anode (oxidation):
$Fe(s) \to F{e^{2 + }} + 2{e^ - }$ ---(a)
Reaction at cathode (reduction):
$2F{e^{2 + }} + 2{O_2}(g) + 4{e^ - } + 2{H^ + } \to F{e_2}{O_3}(s) + {H_2}O(l)$---(b)
Multiplying equation (a) by \[2\] and adding to equation (b),
$2Fe(s) + 2{O_2}(g) \to F{e_2}{O_3}(s) + {H_2}O(l)$
The rusting of iron is a spontaneous process and the isolated rust contains a chemical compound which is hydrated ferric oxide (\[F{e_2}{O_3}.x{H_2}O\]).
Distill water is water which contains no minerals but has dissolved oxygen in it. Rather distilled water contains more dissolved oxygen than ordinary water. The distill water absorbs oxygen from the atmosphere. As a result the distill water on contact with iron oxidizes the iron into iron oxide. Due to this the rusting of iron takes place.
The rusting of iron in distill water is written as
$4Fe(s) + 3{O_2}(g) + 2x{H_2}O(l) \to 2F{e_2}{O_3}.x{H_2}O(s)$
Hence the rusting of iron nails occur in distilled water due to presence of dissolved oxygen in distilled water.

Note:
The rusting of iron in distilled water occurs slowly than the ordinary water as no minerals or dissolved salt are present. The salt solution acts as an electrolyte in the redox process and the reaction proceeds faster.