Chapter 4, Problem 1DQ

Interpretation Introduction

Interpretation: The magnified view of $\text{HCl}$ solution is to be stated. The balanced equation with symbols when magnesium metal in dropped into $\text{HCl}$ solution is to be stated.

Concept introduction: The compounds particularly strong acids function as extremely strong electrolytes and thereby undergoes entire dissociation in given aqueous solution. When some other metal is introduced into its respective solution, there can be occurrence of displacement reaction depending on metal’s reactivity. This reactivity can be easily explained via reactivity series.

Answer to Problem 1DQ

The magnified view of $\text{HCl}$ solution is shown below.

  

The balanced reaction when $\text{Mg}$ metal is dropped into $\text{HCl}$ solution is $\text{Mg}\left(s\right)+2\text{HCl}\left(aq\right)\to {\text{MgCl}}_2\left(aq\right)+{\text{H}}_2\left(g\right)\uparrow$

Explanation of Solution

The $\text{HCl}$ solution comprises of ${\text{H}}^{+}$ ions and ${\text{Cl}}^{-}$ ions as it completely dissociates in its respective solution. This can be illustrated by the reaction which is as follows.

  $\text{HCl}\left(aq\right)\to {\text{H}}^{+}\left(aq\right)+{\text{Cl}}^{-}\left(aq\right)$

The magnified view of this $\text{HCl}$ solution can be depicted as follows.

  

Figure 1

If a magnesium piece is dropped in this $\text{HCl}$ solution, then ${\text{H}}_2$ gas bubblesform. This is because the position of $\text{Mg}$ metal in reactivity series is high in comparison to hydrogen indicating higher reactivity of $\text{Mg}$ than hydrogen.

This results in displacement of hydrogen from $\text{HCl}$ , thereby forming ${\text{MgCl}}_2$ followed by ${\text{H}}_2$ gas evolution as bubbles. The balanced reaction with respective symbols is as follows.

  $\text{Mg}\left(s\right)+2\text{HCl}\left(aq\right)\to {\text{MgCl}}_2\left(aq\right)+{\text{H}}_2\left(g\right)\uparrow$

Therefore, the magnified view of $\text{HCl}$ solution contains ${\text{H}}^{+}$ and ${\text{Cl}}^{-}$ ions and hydrogen undergoes displacement from $\text{HCl}$ forming ${\text{MgCl}}_2$ and ${\text{H}}_2$ .

Conclusion

The magnified view of $\text{HCl}$ solution is represented in Figure 1. Magnesium metal when dropped in $\text{HCl}$ solution forms ${\text{MgCl}}_2$ and ${\text{H}}_2$ , the balanced equation of which is $\text{Mg}\left(s\right)+2\text{HCl}\left(aq\right)\to {\text{MgCl}}_2\left(aq\right)+{\text{H}}_2\left(g\right)\uparrow$ .