Question

3.0 m hydrochloric acid is poured over an iron nail and a reaction happens. which of the following does not occur during the reaction? hydrogen gas forms. chloride ion becomes chlorine gas. iron(ii) chloride or iron(iii) chloride form. the iron nail dissolves.

Explanation:

1. First, recall the reaction between iron (Fe) and hydrochloric acid (HCl): The reaction is a single - displacement reaction. The general reaction is \(Fe + 2HCl=FeCl_{2}+H_{2}\uparrow\) (or if iron is oxidized further, \(2Fe + 6HCl = 2FeCl_{3}+3H_{2}\uparrow\)).

• For the option "Hydrogen gas forms": In the reaction between iron and hydrochloric acid, the hydrogen ions (\(H^+\)) in HCl are reduced to \(H_2\) gas. So this occurs.
• For the option "Chloride ion becomes chlorine gas": In the reaction of iron with hydrochloric acid, the chloride ions (\(Cl^-\)) in HCl do not get oxidized to \(Cl_2\) gas. The iron is oxidized (from 0 to +2 or +3 oxidation state) and the hydrogen is reduced (from +1 to 0 in \(H_2\)). There is no redox process that oxidizes \(Cl^-\) to \(Cl_2\) in this reaction.
• For the option "Iron(II) chloride or Iron(III) chloride form": As seen from the reaction equations \(Fe + 2HCl = FeCl_2+H_2\uparrow\) (formation of iron(II) chloride) and \(2Fe + 6HCl=2FeCl_3 + 3H_2\uparrow\) (formation of iron(III) chloride), iron chlorides are formed. So this occurs.
• For the option "The iron nail dissolves": Since iron reacts with HCl, the solid iron nail (Fe) is consumed in the reaction, so it dissolves.

Answer:

B. Chloride ion becomes chlorine gas.