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What amount of solution propanoate shoul...

What amount of solution propanoate should be added to one litre of an aqueous solution containing `0.02` mole of propanoic acid (`K_(a)=1.0xx10^(-5)` at `25^(@)C`) to obtain a buffer solution of `pH 6`

A

0.1M

B

0.2M

C

0.3M

D

1.3M

Text Solution

Verified by Experts

The correct Answer is:
B
Using the expression
`pH =pK_(a)+log"" (["Salt"])/(["Acid"])`
we get , `6=-log (1.0 xx 10^(-5))+log""(["Salt"])/(["Acid"])`
Which gives `6=5+log"" (["Salt"])/([0.002M])`
`or (["Salt"])/([0.002M])=10 or ["Salt"]`
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