A) \[1.0\times {{10}^{-5}}\]
B) \[1.0\times {{10}^{-9}}\]
C) \[1.0\times {{10}^{9}}\]
D) \[1.0\times {{10}^{14}}\]
Correct Answer: C
Solution :
HA ⇌\[{{H}^{+}}+{{A}^{-}}\]; \[{{K}_{a}}=\frac{[{{H}^{+}}]\,\,[{{A}^{-}}]}{[HA]}\] ??(i) neutralization of the weak acid with strong base is \[HA+O{{H}^{-}}\]⇌ \[{{A}^{-}}+{{H}_{2}}O\] \[K=\frac{[{{A}^{-}}]}{[HA]\,\,[O{{H}^{-}}]}\] ??(ii) dividing (i) by (ii) \[\frac{{{K}_{a}}}{K}=[{{H}^{+}}]\,\,[O{{H}^{-}}]\]\[={{K}_{w}}={{10}^{-14}}\] \[K=\frac{{{K}_{a}}}{{{K}_{w}}}=\frac{{{10}^{-5}}}{{{10}^{-14}}}={{10}^{9}}\].You need to login to perform this action.
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