# Doubts from ionic equilibrium

#1
Doubt from Capacitance
Arrange compound in image in decreasing order of sn2
#2

First write reaction b/w both the given things, then the ones left form buffer.

#3

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

#4

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

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#5

How do you judge if we can neglect it or not in a buffer
@Ankith_2020

#6

I am getting 10.4
Can u post the soln ankith_2020

#7

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

#8

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

#9

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.

#10

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!!!

#11

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.

#12

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

#14

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

#15

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.

#16

Thank you !!

#17

Yes I got it ...thanks

#18

So what's the final answer then?

#19

6.7

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