1.

A certain buffer solutions contains equal concentration of X^(-) and HX. The K_(b) for HX is 10^(-10). The pH of the buffer is

Answer»

4
7
10
14

Solution :`X^(-) + H_(2)O hArr OH^(-) + HX`
`K_(b) = ([OH^(-)][HX])/([X^(-)])`
`HX hArr H^(+) + X^(-)`
`K_(a) = ([H^(+)][X^(-)])/([HX]), :. K_(a) xx K_(b) = [H^(+)][OH^(-)] = K_(w) = 10^(-14)`
HENCE `K_(a) = 10^(-4)`
Now as `[X^(-)] = [HX], pH = pK_(a) = 4`.


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