1.

It has been found that the pH of a 0.01 M solution of an organic acid is 4.15. Calculate the concentration of the anion, the ionization constant of the acid and its pK_a

Answer»

SOLUTION :`HAleftrightarrowH^+`
`thereforepH=log[H^+]ORLOG[H^+]=-4.15=5.85`
`[A^-]=[H^+]=7.08 times10^-5M`
`K_a=([H^+][A^-])/([HA])=((7.08 times10^-5)(7.08 TIMES 10^-5))/10^-2=5.0 times 10^-7`
`pK_a=-logK_a=-log(5.0 times10^-7)=7-0.699=6.301`


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