Question

What happens when dilute hydrochloric acid is added to iron filling?

Answer 1

Hint: According to the reactivity series, the elements present above the hydrogen will displace it from its acid solution whereas the element present below hydrogen will not displace hydrogen from its acid solution.

Complete step by step solution:
In the reactivity series, the elements are arranged in their decreasing order of reactivity. The reactivity series is also known as the activity series. The most reactive elements are placed above in the series and the least reactive elements are placed below in the reactivity series.
Iron is present above hydrogen in the reactivity series which means Iron is more reactive than hydrogen. So, the iron will displace the hydrogen atom from its acid solution.
The reaction taking place between iron and hydrochloric acid is a single displacement reaction.

A single displacement reaction shows the displacement of the less reactive element from its compound by a more reactive element which results in the formation of a new compound. It is also termed a replacement reaction.

When acid reacts with metal, salt is formed with the liberation of hydrogen gas.
The general reaction is shown below:
$Acid + Metal \to Salt + Hydrogen$
The reaction between the iron filling and hydrochloric acid is shown below:
$2HCl(dil) + Fe(s) \to FeC{l_2}(aq) + {H_2}(g)$
In the given reaction, hydrochloric acid reacts with iron to form iron chloride as the main product by liberating hydrogen gas.
Therefore, when dilute hydrochloric acid is added to iron filling iron(II) chloride is formed.

Note: Iron reacting with hydrochloric acid forms iron chloride where iron is in +2 oxidation state whereas when iron reacts with chlorine it also forms iron chloride but here iron is in +3 oxidation state. The reaction between iron and chlorine is a type of redox reaction.
The reaction between iron and chlorine is shown below:
$2Fe(s) + 3C{l_2}(g) \to 2FeC{l_3}(s)$