Q4.68P - Chemistry: Molecular Nature Of Matter And Change

Question

Give the oxidation number of arsenic in the following:

$$\begin{gathered} \left(a\right)As{H}_3 \\ \left(b\right)H_{2}As{O}_4^{-} \\ \left(c\right)AsC{l}_3 \end{gathered}$$

Step-by-Step Solution

Answer

You need to provide the oxidation number of arsenic for the given compounds.

Step 1: Oxidation state of arsenic in AsH 3

Oxidation state of Hydrogen is +1.

Let, oxidation state of arsenic in AsH₃ is x.

No you can write,

  $$\begin{gathered} x+3\left(+1\right)=0 \\ x=-3 \end{gathered}$$

Hence, oxidation state of arsenic in AsH₃ is -3.

Step 2: Oxidation state of arsenic in H 2 AsO 4 -

Oxidation state of Hydrogen is +1.

Oxidation state of Oxygen is -2.

Let, oxidation state of arsenic in H₂AsO₄^- is y.

No you can write,

  $$\begin{gathered} 2\left(+1\right)+y+4\left(-2\right)=-1 \\ y=+5 \end{gathered}$$

Hence, oxidation state of arsenic in H₂AsO₄^- is +5.

Step 3: Oxidation state of arsenic in AsCl 3

The oxidation state of Chlorine is -1.

Let, oxidation state of arsenic in AsCl₃ is z.

No you can write,

  $$\begin{gathered} z+3\left(-1\right)=0 \\ z=+3 \end{gathered}$$

Hence, oxidation state of sulfur in H₂SO₃ is +4.