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Q: Calculation of Acid Constant ( Answered ,   0 Comments ) Question
 Subject: Calculation of Acid Constant Category: Science > Chemistry Asked by: medicine_man-ga List Price: \$9.00 Posted: 19 Nov 2006 22:30 PST Expires: 19 Dec 2006 22:30 PST Question ID: 784170
 ```The pH of a 0.55 mol L-1 solution of a weak acid, HZ, is 3.76. Calculate Ka for HZ? Please show workings. Cheers.``` Subject: Re: Calculation of Acid Constant Answered By: livioflores-ga on 27 Nov 2006 22:07 PST Rated: ```Hi!! Assuming that the dissociation equation is: HZ(aq) <---> H+ + Z- (aq) Then: Ka = [H+]^2/[HZ] ([H+] = [Z-]) [H+] = 10^(-pH) = 10^(-3.76) = 1.7378*10^-4 Therefore: Ka = (1.7378*10^-4)^2/0.55 = 5.491*10^-8 At the following Powerpoint file you will find an excellent source for a further reading and explanations on this topic: "Acids and Bases" by Tsun-Mei Chang at University of Wisconsin-Parkside site: http://uwp.edu/~chang/C102/ch16/chang-16.ppt I hope this helps you. Feel free to request for a clarification if you need it. Best regards, livioflores-ga```
 medicine_man-ga rated this answer: `Excellent answer thanks for your help :)`  