If first dissociation of $X(OH)_{3}$ is 100% where as second dissociation is 50% and third dissociation is negligible then the $pH$ of $4 imes 10^{- 3}$ M $X(OH)_{3}$ is

Question

If first dissociation of $X(OH)_{3}$ is 100% where as second dissociation is 50% and third dissociation is negligible then the $pH$ of $4 	imes 10^{- 3}$ M $X(OH)_{3}$ is

Dr. Abubacker · Accepted Answer

(c)
First dissociation
$X(OH)_{3} ightarrow X(OH)_{2}^{+} + OH^{-}$
Second dissociation
$X(OH)_{2}^{+} ightarrow X(OH)^{2 +} + OH^{-}$
Total $\left\lbrack OH^{-} ightbrack = 4 	imes 10^{- 3} + 2 	imes 10^{- 3}$
$= 6 	imes 10^{- 3}$
$pOH = 3 - \log 6$
$= 3 - 0.78 = 2.22$
$pH = 14 - 2.22 = 11.78$

Q. If first dissociation of $X(OH)_{3}$ is 100% where as second dissociation is 50% and third dissociation is negligible then the $pH$ of $4 \times 10^{- 3}$ M $X(OH)_{3}$ is

Explanation

Reviewed by Dr. Abubacker

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