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#1
May 12 2013 09:54pm
What is the pH of a solution prepared by mixing 100 mL of 0.0500M HCl with 300 mL of 0.500M HF?
[Ka(HF) = 0.00071]

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#2
May 12 2013 09:55pm
moles of HCl = 0.05 * .1L = 0.005 mol/L HCl
moles of HF = 0.5 * .3L = .15 mol/L HF

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#3
May 12 2013 10:09pm
I'm stuck here, can somebody help :)
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#4
May 12 2013 10:43pm
[H] = .005/.4L = 0.125
[H] = .15/.4L = .375

pKa = 3.15

pH = 3.15 + log (.0125 / .375) = 1.67

Answer is pH = 1.63

Some Ting WOng
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#5
May 12 2013 11:00pm
.15/.005 = 30

pH = pKa - log (weak acid / strong acid)
pH = 3.15 - log (30)
pH = 3.15 - 1.477
pH = 1.673


still not it..
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#6
May 13 2013 06:34pm
http://answers.yahoo.com/question/index?qid=20090206225018AAVzppv

this might help

HCl completely dissociates by 'definition of a strong acid' so the amount of H+ will be the amount of moles of HCl which is 0.005 according to your math, sorry dont have a calc
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