Sapling Learning Due Date: Points Possible: Grade Category The Ka for the H2PO4

Question

Sapling Learning Due Date: Points Possible: Grade Category The Ka for the H2PO4 /HPO buffer is given by the equation: Description: K. 10-7.20 Policies: You can check your You can view solutio give up on any ques You can keep trying until you get it right You lose 5% of the answer in your quest attempt at that answ What is the pH of a 1:2 mixture of H2PO4 to HPO (See the table for the activity coefficients.) at 0.10 M ionic strength? Ionic Strength ( M) 0.005 0.010 0.0500.10 0.933 0.914 0.86 0.83 0.740 0.660 0.445 0.355 0.928 0.902 082 0.775 Number O eTextbook HPO H.PO O Help With This Topi Web Help & Videos TechnicalSupota -O Previous & Give Up & View Solution O check Answer 0 Next el Exit-

Explanation / Answer

if IS = 0.1

then, use the last right side column values

then

if mix is 1:2 vs H2PO4- : HPO4-2

10^-7.20 = 0.83*[H+] * (0.355) * [HPO4-2] / ([H2PO4-] * 0.775)

10^-7.20 = 0.83*0.355/0.775 * [H+] [HPO4-2] / [H2PO4-]

(10^-7.20)/0.3801 = [H+] [HPO4-2] / [H2PO4-]

1.65991*10^-7 = [H+] * (2/1)

(1.65991*10^-7/2 = [H+]

[H+] = 8.299+10^-8

pH = -log(8.299+10^-8)

pH = 7.080

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