Question

Which one of the following is observed when dilute HCl is added to iron fillings in a conical flask?

• A. Chlorine gas is liberated and ferrous chloride is formed,
• B. Hydrogen gas is liberated and ferrous chloride is formed.
• C. Oxygen and hydrogen are liberated and ferric chloride is formed in the solution.
• D. No change is observed

Answer 1

The correct option is B

Hydrogen gas is liberated and ferrous chloride is formed.

Explanation for correct answer

B. The reactions that involve the displacement of the cations and anions present in the reactant compounds are called displacement reactions.

The reaction between Iron and dilute Hydrochloric acid is shown below.

$$\begin{gathered} \mathrm{Fe}\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{FeCl}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right) \\ \mathrm{Iron}\mathrm{Hydrochloric}\mathrm{Iron}\mathrm{chloride}\mathrm{Hydrogen} \\ \mathrm{acid} \end{gathered}$$
Iron (Fe) undergoes a reaction with dilute HCl to give Ferrous chloride $\left({\mathrm{FeCl}}_2\right)$, and Hydrogen gas is liberated as a byproduct. This is an example of a displacement reaction. Chlorine gas or Oxygen is not liberated in the reaction process.

Explanation for incorrect answers

The displacement reaction of Iron and dilute Hydrochloric acid shows that the only gas liberated after the reaction is Hydrogen gas. Hence options A and C are incorrect. Moreover, the reaction is feasible by forming ferrous chloride $\left({\mathrm{FeCl}}_2\right)$ and not ferric chloride $\left({\mathrm{FeCl}}_3\right)$. Hence, option C is also incorrect.

Therefore, the correct answer is option B. Hydrogen gas is liberated and Ferrous chloride is formed.