1.

2.5 mL of 2/5 M weak monoacidic base (K_(b)=1xx10^(-12)" at "25^(@)C) is titrated with 2/15 M HCl in water at 25^(@). The concentration of H^(+) at equivalence point is (K_(w)=1xx10^(-14)" at "25^(@)C)

Answer»

`3.7xx10^(-13)M`
`3.2xx10^(-7)M`
`3.2xx10^(-2)M`
`2.7xx10^(-2)M`

Solution :The base is very weak, the CATIONS of the SALT formed at the equivalence point shall undergo hydrolysis to a greater extent and so the degree of hydrolysis, h cannot be neglected in comparison to 1. Now apply
`Kh=(Ch^(2))/(1-h)=K_(w)/K_(b),C=0.1M,[H^(+)]=Ch`


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