Answer:

Explanation:
Assume Ksp of
=
( it is general value ,i took it because not given in question)
molar solubilty means how much maximum mole of lead thiocynate is dissolved in one litre of solvent.
Ksp=solubility product;

Lets molar solubilty of
is S then
![[Pb^{+2}]=S;](https://tex.z-dn.net/?f=%5BPb%5E%7B%2B2%7D%5D%3DS%3B)
![[SCN^{-1} ]=2S;](https://tex.z-dn.net/?f=%5BSCN%5E%7B-1%7D%20%5D%3D2S%3B)



Answer:
pH of soltion will be 5.69
Explanation:
The pH of the solution will be due to excessive acid left and the salt formed. Thus, it will form a buffer solution.
The pH of buffer solution is calculated from Henderson Hassalbalch's equation, which is:
![pH=pKa+log(\frac{[salt]}{[acid]} )](https://tex.z-dn.net/?f=pH%3DpKa%2Blog%28%5Cfrac%7B%5Bsalt%5D%7D%7B%5Bacid%5D%7D%20%29)


The moles of acid taken :

The moles of base taken:

The moles of acid left after reaction :

The moles of salt formed = 4.5mmol
Putting values in equation
![pH=pKa+log(\frac{[salt]}{[acid]} )=4.74+log(\frac{4.5}{0.5})=5.69](https://tex.z-dn.net/?f=pH%3DpKa%2Blog%28%5Cfrac%7B%5Bsalt%5D%7D%7B%5Bacid%5D%7D%20%29%3D4.74%2Blog%28%5Cfrac%7B4.5%7D%7B0.5%7D%29%3D5.69)