Question

some chemical reactants are listed in the table below. complete the table by filling in the oxidation state of the highlighted atom.

species	oxidation state of highlighted atom
o₂(g)
cucl(s)
hpo₄²⁻(aq)

Explanation:

Step1: Determine oxidation state of O in OH⁻

Oxygen usually has an oxidation - state of - 2 in most of its compounds. In the hydroxide ion ($OH^-$), let the oxidation state of O be $x$ and of H be + 1. The overall charge of the ion is - 1. So, $x+( + 1)=-1$, solving for $x$ gives $x=-2$.

Step2: Determine oxidation state of O in $O_2$

In a free element, the oxidation state of each atom is 0. Since $O_2$ is an elemental form of oxygen, the oxidation state of O is 0.

Step3: Determine oxidation state of Cu in CuCl

Chlorine has an oxidation state of - 1 in binary metal - chloride compounds. Let the oxidation state of Cu be $y$. In CuCl, $y+( - 1)=0$ (because the compound is neutral), so $y = + 1$.

Step4: Determine oxidation state of P in $HPO_4^{2 - }$

Hydrogen has an oxidation state of + 1 and oxygen has an oxidation state of - 2. Let the oxidation state of P be $z$. The overall charge of the ion is - 2. So, $(+1)+z + 4\times(-2)=-2$. Simplifying gives $1 + z-8=-2$, then $z=+5$.

Answer:

species	oxidation state of highlighted atom
$O_2(g)$	0
$CuCl(s)$	+ 1
$HPO_4^{2 - }(aq)$	+ 5