12.19

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Or Fisher 1I
Posts: 35
Joined: Fri Feb 02, 2018 3:00 am

12.19

Postby Or Fisher 1I » Sat Jun 09, 2018 11:05 am

Hello, I am struggling to understand question 12.19 from the textbook,
The concentration of HCl in hydrochloric acid is reduced to 12% of its initial value by dilution. What is the difference in the pH values of the two solutions?
The answer says that pH will increase by 0.92 but how do we calculate this if we do not know the initial pH?
Thanks.

NatalieSDis1A
Posts: 39
Joined: Fri Apr 06, 2018 11:05 am

Re: 12.19

Postby NatalieSDis1A » Sat Jun 09, 2018 12:13 pm

Hello, we are trying to find the difference so we should subtract pH final - pH initial.
initial pH = -log (HCl)
final pH = -log(.12HCl)
final - initial = -log(.12HCl) - -log(HCl)
-(log(.12HCl)- log(HCl))
** log law: logA - logB = log (A/B)
-log (.12HCL/HCl)
-log(.12) = .92


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