Question

State one relevant observation for the following:
Lead Nitrate solution is treated with sodium hydroxide solution drop by till it is in excess

Answer 1

Double displacement reaction takes place when lead nitrate solution is treated with sodium hydroxide solution. Sodium hydroxide $(NaOH)$ is a very strong base. Sodium are lead are cations and they quickly dissociate in the solution as they are not held properly in the structure.

Complete step by step answer:
When we mix lead nitrate $Pb{(N{O_3})_2}$ with sodium hydroxide $(NaOH)$ we get lead hydroxide and sodium nitrate. Here is the chemical reaction;
$Pb{(N{O_3})_2}{_{\text{aq}}} + 2NaO{H_{aq}} \to Pb{(OH)_2} + 2NaN{O_{3(aq}}_)$
The chemical reaction taking place here is double displacement reaction and the product formed is lead hydroxide.
When sodium hydroxide solution is applied dropwise to lead nitrate solution, it first provides a white precipitate due to the presence of lead hydroxide $Pb{(OH)_2}$ and then a translucent solution is obtained by applying excess sodium hydroxide solution leading to the formation of colourless and soluble sodium plumbite $N{a_2}Pb{O_2}$ . Here is the chemical reaction for this process;
$Pb{(OH)_2} + 2NaOH$ $($ Excess $)$ $\to N{a_2}Pb{O_2}$

Additional Information:
Sodium plumbite formed in the above reaction is known as a doctor solution. The following are some properties of sodium plumbite;
1.In nature, it is poisonous and corrosive.
2.Sodium plumbite is utilised to sweeten fuel.
3.This gasoline sweetening process is known as the process of physician sweetening.
4.It is a sodium hydroxide solution of lead oxide.

Note:
In a solution, lead can rapidly dissociate since it is a cation that is not tightly held together with nitrate. Sodium is also a cation which, when in the solution, is not strongly linked to hydroxyl group. The negatively charged molecules of hydroxide and nitrate ions would basically attract sodium and lead ions.