Question

What happens when dilute hydrochloric acid is added to iron fillings?
a.) Hydrogen gas and iron chloride are produced
b.) Chlorine gas and iron hydroxide are produced
c.) No reaction takes place
d.) Iron salt and water are produced

Answer 1

Hint: You should be aware that when a metal is reacted with dilute hydrochloric acid, it produces salt of respective metal and gas. Now try to write the balanced equation to reach the final answer.

Complete step by step answer:

Let us consider the reaction between acid and metal is
Acid + Metal → Salt + Hydrogen gas ($H_{ 2 }$)
in this case, acid is dilute hydrochloric acid and metal is Iron (Fe)
Therefore, we can write it as,
$HCl\quad +\quad Fe\quad \rightarrow \quad FeCl_{ 2 }\quad +\quad H_{ 2 }$
Let us balance the equation,
$2HCl\quad +\quad Fe\quad \rightarrow \quad FeCl_{ 2 }\quad +\quad H_{ 2 }$
So we can say that the iron displaces hydrogen from hydrochloric acid to form iron (II) chloride & hydrogen gas. This is a single displacement reaction. When dilute HCl is added to Fe then ferrous chloride ( $FeCl_{ 2 }$) and hydrogen gas ($H_{ 2 }$) will be formed.
In terms of physical observations, there will be a period of rapid bubbling as the hydrogen gas escapes and a thin layer of iron(III) chloride may form.

Thus, the correct answer to this question is option A, hydrogen gas and iron chloride are produced.

Note: We should also know about the single displacement reaction.
A single replacement reaction, sometimes called a single displacement reaction, is a reaction in which one element is substituted for another element in a compound. When a replacement reaction occurs, a new aqueous compound and a different pure element will be generated as products.