5 pts Question 6 Given: HOCI has a Ka = 2.9 x 10-8 and a pka = 7.54 You are titrating 20.0 mL of a 0.200 M HOCI with a 0.200 M NaOH. The equivalence point volume is therefore 20.0 mL of NaOH. You stop the titration early when you have added 15.0 mL of NaOH to check the pH and see if it matches the theoretical value. Theoretical pH Analysis (in buffer range) . Before titration, you have [Select] millimoles of HOCI The 15.0 mL of NaOH adds [Select] millimoles of OH. . Since the OH reacts almost completely, you should make [ Select) millimoles of OCI. This would leave [Select ] V millimoles of unreacted HOCI. . Since this is now a buffer solution, the pH would equal [ Select]
Using the question above, you overshoot the endpoint by adding an extra 10.0 mL of NaOH (you added 30.0 mL instead of 20.0 mL). The total volume is now 50.0 mL. What is the pH at this point? (Hint: pH past equivalence point is governed by the excess OH in the total volume) (Hint: [OH-] = mmol of excess OH divided by 50.0 mL)
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