Calculating pH with and without ionic strength

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To calculate the pH of a 0.00196M HCl solution, the initial pH without considering ionic strength is found to be 2.71, as HCl fully dissociates. The discussion raises questions about how to incorporate ionic strength into pH calculations, particularly when using the activity coefficient. Additionally, there is uncertainty regarding the dissociation of HCl in the presence of Na2SO4 and how this affects the pH. Participants seek equations that relate ionic strength to activity coefficients to aid in these calculations. Understanding these concepts is essential for accurate pH determination in varying ionic environments.
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Homework Statement


There are four things to be calculated:

-pH of 0.00196M solution of HCl in water, without taking ionic strength into account,

-The same thing but taking ionic strength into account

-pH of 0.00196M solution of HCl in Na2SO4, without taking ionic strength into account,

-And the same thing but taking ionic strength into account.

Homework Equations


pH = -log([H+])

3. The Attempt at a Solution
So far I've done the first one only. HCl dissociates fully, so pH is - log10(0.00196) = 2.71.

But:
1. How to include "ionic strength" into pH calculation? I have no idea how to do it.
2. How to calculate pH of HCl in Na2SO4? How will it dissociate?
 
Physics news on Phys.org
1. Do you know an equation relating activity coefficient to ionic strength?
2. Completely. But the ionic strength is different.
 

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