Question

Draw Lewis structures for the ${\mathbf{\text{AsCl}}}_{\mathbf{\text{4}}}^{\mathbf{\text{+}}}$and${\mathbf{\text{AsCl}}}_{\mathbf{\text{6}}}^{\mathbf{\text{-}}}$ions. What type of reaction (acid–base, oxidation–reduction, or the like) is the following?

${\mathbf{\text{2AsCl}}}_{\mathbf{\text{5}}}\mathbf{\text{(g)}}\mathbf{\to }{\mathbf{\text{AsCl}}}_{\mathbf{\text{4}}}{\mathbf{\text{AsCl}}}_{\mathbf{\text{6}}}\mathbf{\text{(s)}}$

Short answer

The Lewis structure for and are as follows –

${\text{AsCl}}_{\text{4}}^{\text{+}}$

${\text{AsCl}}_{\text{6}}^{\text{-}}$

Also, the reaction${\text{2AsCl}}_{\text{5}}\text{(g)}\to {\text{AsCl}}_{\text{4}}{\text{AsCl}}_{\text{6}}\text{(s)}$ represents an oxidation-reduction reaction.

Step-by-step solution

Concept Introduction:

The phrases oxidation and reduction refer to the addition or removal of oxygen from a chemical. The process of gaining oxygen is known as oxidation. The loss of oxygen is referred to as reduction.

Lewis structure for AsCl4 + 

Electronic configuration of $\text{As}$is ${\text{[Ar]3d}}^{\text{10}}{\text{4s}}^{\text{2}}{\text{4p}}^{\text{3}}$. Hence, the number of valence electrons of $\text{As}$is.

Electronic configuration of $Cl$is${\text{[Ne]3s}}^{\text{2}}{\text{3p}}^{\text{5}}$. Hence, the number of valence electrons of $\text{As}$is$7$.

Lewis structure for ${\text{AsCl}}_{\text{4}}^{\text{+}}$–

Total valence electrons of${\text{AsCl}}_{\text{4}}^{\text{+}}$is equal to$\text{5 + 4·7 - 1 = 32}$.

The Lewis structure is shown in the figure below.

Step 3:Lewis structure for AsCl6 - 

Lewis structure for${\text{AsCl}}_{\text{6}}^{\text{-}}$–

Total valence electrons of ${\text{AsCl}}_{\text{6}}^{\text{-}}$is equal to $\text{5 + 6·7 + 1 = 48}$.

The Lewis structure is shown in the figure below.

The given reaction is shown below.

${\text{2AsCl}}_{\text{5}}\text{(g)}\to {\text{AsCl}}_{\text{4}}{\text{AsCl}}_{\text{6}}\text{(s)}$

The oxidation state of arsenic is in${\text{AsCl}}_{\text{5}}$is$+5$$+5$. inlocalid="1663769025470" ${{\text{AsCl}}^{-}}_4$is$+4$and in${{\text{AsCl}}^{+}}_6$is$+6$.

Since the oxidation state of arsenic simultaneously increases and decreases from$+5$to$+6$, and from$+5$to$+4$.

Therefore, it can be concluded that the given reaction is an oxidation-reduction reaction.