Question

what is the oxidation state of: a. nitrogen in no₃⁻? b. sulfur in h₂so₃? c. mercury in hg²⁺?

Explanation:

Step1: Recall oxidation - state rules for $NO_3^-$

Oxygen has an oxidation state of - 2 in most compounds. Let the oxidation state of nitrogen be $x$. The overall charge of the $NO_3^-$ ion is - 1. So, $x+3\times(-2)=-1$.

Step2: Solve for $x$ in the equation for $NO_3^-$

$x - 6=-1$, then $x=-1 + 6=+5$.

Step3: Recall oxidation - state rules for $H_2SO_3$

Hydrogen has an oxidation state of + 1 and oxygen has an oxidation state of - 2. Let the oxidation state of sulfur be $y$. The overall charge of the $H_2SO_3$ molecule is 0. So, $2\times(+1)+y + 3\times(-2)=0$.

Step4: Solve for $y$ in the equation for $H_2SO_3$

$2 + y-6 = 0$, then $y=6 - 2=+4$.

Step5: Recall oxidation - state rules for $Hg^{2+}$

For a monatomic ion, the oxidation state is equal to the charge of the ion. So the oxidation state of mercury in $Hg^{2+}$ is + 2.

Answer:

A. +5
B. +4
C. +2