Question

The pH of 0.1 M solution of cyanic acid (HCNO) is 2.34. Calculate the ionization constant of the acid and its degree of ionization in the solution .

Answer 1

`HCNO hArr H^(+)+CNO^(-)`
`pH = 2.34 "means" - log [H^(+)]= 2.34 or log [H^(+)]=2.34 or log [H^(+)]=-2.34 = bar(3).66`
or `[H^(+)] = "Antilog" bar(3).66 = 4.57 xx 10^(-3) M`
`[CNO^(-)]=[H^(+)]=4.57 xx 10^(-3) M`
`K_(a)=((4.57xx10^(-3))(4.57xx10^(-3)))/(0.1)=2.09xx10^(-4)`
`alpha = sqrt(K_(a)//C)=sqrt(2.09xx10^(-4)//0.1)=0.0457`.