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pH of 0.56M HF (pKa = 3.14)
Posted: Sun Oct 05, 2014 7:34 am
by jokulsa
How do I find the pH of 0.56M of hydrofluoric acid HF?
(pKa = 3.14)
Posted: Thu Oct 09, 2014 12:12 am
by GrahamKemp
Look to the left. At the top of the menu is "Chemistry tool". Click this. Then follow the link on the next page to "pH calculator".
In the text box labelled "Enter components of a solution to calculate pH" enter:
Then click "Compute pH" and scroll down to the answer.
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Components of the solution (mixture):
Name: HF
Initial concentration after solutions are mixed = 0.56
Ka
1 = 0.00072443596007499 ( pKa
1 = 3.14 )
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Answer:
[H+] = 0.019782630261034
[OH-] = 5.0549395444635E-13
pH = 1.7037159659284
pOH = 12.296284034072
Ka
1 = 0.00072443596007499 ( pKa
1 = 3.14 )
Posted: Thu Oct 09, 2014 12:40 am
by GrahamKemp
Or by hand:
The equilibrium equation, where
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Ka = [H][F]/[HF]
If there is no other source of hydronium ions than the acid (assuming a negligible contribution from water) then
If the
initial concentration of HF is
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Ka = [H]{2} / (C-[H])
Which rearranges to:
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[H]= (-Ka + sqrt(Ka{2} + 4 C Ka ))/2
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[H]= (-10^{-3.14} + sqrt( 10^{-6.28 x 2} + 4 x 0.56 x 10^{-3.14} ))/2
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[H] = 0.01978264090522295443508279585463
Code: Select all
-log10 [H] = 1.7037157322531579844483334967812
Re: pH of 0.56M HF (pKa = 3.14)
Posted: Sun Nov 03, 2024 9:42 pm
by Reatele
Probably no need to write out the solution for this question, right?
The pH of the 0.56 M HF solution is approximately 1.70.