12.19; find change in pH for weak acids?

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ZoeHahn1J
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12.19; find change in pH for weak acids?

Postby ZoeHahn1J » Thu Dec 07, 2017 2:11 pm

Question 12.19 asks one to find the difference in the pH values of two solutions, one of which the concentration of HCl has been diluted to 12% of its initial value. To do this, we can use change in pH = (.12 x [HCl]o/[HCl]o) =.92. Could we use this same rule for weak acids as well?

Nisarg Shah 1C
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Re: 12.19; find change in pH for weak acids?

Postby Nisarg Shah 1C » Thu Dec 07, 2017 2:38 pm

No because this rule is only valid because strong acids completely disassociate in water. You would have to do the equilibrium calculations for a weak acid because not all of it disassociates.

Oscar Beltran 3H
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Re: 12.19; find change in pH for weak acids?

Postby Oscar Beltran 3H » Thu Dec 07, 2017 6:21 pm

How exactly do we find the change in pH if we are not given the initial pH of HCl?


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