Question

What is the Oxidation number of the metal in Lead Hydroxide?

Answer 1

Hint: Lead Hydroxide has the chemical formula of $Pb{(OH)_2}$. Lead belongs to the d-block, transition metals group and has variable oxidation states. The overall charge on this compound is nil or zero, and it is neutrally charged.

Complete answer:
To find the oxidation number of the metal Pb we’ll disintegrate the compound $Pb{(OH)_2}$ . The reaction goes as:
$Pb{(OH)_2} \to P{b^{ + 2}} + 2(O{H^ - })$
$O{H^ - } \to {H^ + } + {O^{2 - }}$
The overall reaction hence will be:
$Pb{(OH)_2} \to P{b^{ + 2}} + 2{O^{2 - }} + 2{H^ + }$
Here, Pb will have a positive charge because the electronegativity of Pb is less than that of Oxygen. The more electronegative atom will have a negative charge, and the less electronegative atom will have positive charge on it. Oxygen will always have a -2 oxidation state, except when it is with a more electronegative element like Fluorine ( where oxygen shows -1 oxidation state). Hence both Pb and H will have positive charge. Since the whole -OH ion has -1 overall charge on it, to compensate for the negative charge $2 \times ( - 1) = - 2$, Pb will have a $ + 2$ oxidation state.
Therefore, the oxidation state of Metal Pb in Lead Hydroxide is $ + 2$

Additional information:
Lead (II) Hydroxide acts like a weak base forming $P{b^{ + 2}}$ , which is dissolved in a weakly acidic solution. When the alkalinity is progressively increased it forms $Pb{(OH)^ + },Pb{(OH)_2}$ and other species.

Note:
The alternate and easy way to find the oxidation states is by remembering the general oxidation states of common elements like Oxygen, Hydrogen, Carbon etc. We know that the overall charge on the molecule is 0. Consider the O.S of Pb to be “X”. It can be given as:
$x + 2( + 1) + 2( - 2) = 0$
$x - 2 = 0$
$x = + 2$