Doubt from Ionic Equilibrium


Please help me in Q 7 , I think I am missing a small concept here.

I guess normal salt hydrolysis should work out well
pH= 14-(7+0.5(pk_a+logC))

Although its possible I've forgotten the formula :sweat_smile:
Do tell the exact issue, it'll be more helpful. @Gaurav_Singh11

PS is the answer 5.15?

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Edit it should be pk_b not pk_a .

@Devanshu_Shah , it may be a basic doubt but how to find log C in this question.

This one is indeed tricky even I made a mistake the first time :sweat_smile: (took moles instead of equivalents, read along to know why its wrong)
In the question H+ is 5meq so we need 5meq NH3 so 40ml NH3
This will lead to form 5meq of salt
So conc of salt will be 5meq/50ml

Note: I used equivalent in finding the conc of salt since effectively we need the [NH4+] not the salt

Cheers! :smiley:
@Gaurav_Singh11

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Can anyone help me in 2nd Question

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Is it 10.75?

It's 9.6

20200904_124448

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