Determine the hydrogen ion concentration in `1.0 ` M solution of HCN , if its dissociation constant is `4.0 xx 10^(-10)`.

Explanation

`HA = H^(+) + A^(-)`
Applying Ostward.s dilution law for weak acid,
`alpha = sqrt(k_(a) V)`
`k_(a) = 4.0 xx 10^(-10)`
`v = ( 1)/( 0.01 ) = 100` litre
`alpha = sqrt(4 xx 10^(-10) xx 10^(2)) = 2 xx 10^(-6) `mol `L^(-1)`
or concentration of hydrogen ions
`= ( prop)/( v) = ( 2 xx 10^(-4))/( 100) = 2 xx 10^(-6) mol L^(-1)`
or concentrated hydrogen ions
`=sqrt( kc) = sqrt( 4 xx 10^(-10) xx 0.01) = 2 xx 10^(-6) mol L^(-1)`