question_answer

The dissociation constants for acetic acid and HCN at \[{{25}^{o}}C\] are \[1.5\times {{10}^{-5}}\] and \[4.5\times {{10}^{-10}},\] respectively. The equilibrium constant for the equilibrium,  \[HCN+C{{H}_{3}}CO{{O}^{-}}\] would be                                                    [AIPMT (S) 2009]

A)  \[3.0\times {{10}^{5}}\]         

B)       \[3.0\times {{10}^{-5}}\]

C)  \[3.0\times {{10}^{-4}}\]        

D)       \[3.0\times {{10}^{4}}\]

Correct Answer: D

Solution :

Given,

(i)

(ii)

On substracting Eq. (ii) from Eq. (i), we get

White adding two equations, dissociation constants are multiplied and when subtracting the equations, dissociation constants are divided.

Alternative

(i)

(ii)

(iii)

From Eqs. (i), (ii) and (iii),