Doubts from ionic equilibrium


Doubt from Capacitance
Arrange compound in image in decreasing order of sn2

First write reaction b/w both the given things, then the ones left form buffer.
Hence answer shall be A.


ans is D and can you write the equations as i am confused about product


I have tried that question . H+ from water is not negligible which make question lengthy.

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How do you judge if we can neglect it or not in a buffer


I am getting 10.4
Can u post the soln ankith_2020


Well pH =10.4 is never possible because this is an acidic solution. This happen because of neglecting H+ from water.


@Soumyadeep_2019 Considering this as a buffer soln and neglecting second dissociation provide answer as (A) 6.4 .


this approach to question is valid?
I assume it as a buffer of WA and SB and react them both.Here,WA is h2co3 and as co3 is a conjugate bases of WA (hco3) having really small ka so it's conjugate base would be strong one.From this concept,I tried to avoid equilibrium in reaction.


In this reaction (the reaction you wrote) the equilibrium constant is not Ka1,it is Ka1/Ka2.
And also you can not use that formula directly ,that formula is derived for a weak mono basic acid with its anion(Buffer).
Basically in your equation you haven’t mentioned H+ ion ,so we can not find it’s concentration.
I feel it’s not the right method, pls correct me if i am wrong and i am not getting answer matching the options!!!


Sir but CO3 2- is conjugate base of a weak acid(hco3 -)
We know conjugate base of a weak acid is strong base.So why can’t the solution be basic in nature?Pls someone give solution for this question.


I used ka1 based on derivation of formula of acidic buffer and h+ also comes from that.but I m not sure that react of h2co3 and co32- will complete or not


Ignore every post where I talk about considering H+ from water. As I hadn't go through condition of buffer soln generated from polybasic acid so there was a lot of confusion. @darshil_2020 your method is correct and I hope this helps you


As this is an acidic buffer solution and pH of acidic buffer solution is always less than or equal to 7. I hope you got my point why I said pH=10.4 is not possible.


Thank you !!


Yes I got it ...thanks


So what's the final answer then?



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