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story Bookmarks Window Help saplinglearning.ca GenChem -Winter18-DEPT: Assi.. www. sapl inglearning calibisicss/Accessibility.php?text=You%20need%20to%e Jump to. O 3/14/2018 09:01 AM O 56.9/1003/11/2018 01:19 PM Gradebook Caiculator Periodic Table Question 13 of 28 Sapling Learning Map You need to prepare an acetate buffer of pH 5.92 from a 0.730 M acetic acid solution and a 2.63 M KOH solution. If you have 575 mL of the acetic acid solution, how many millsiters of the KOH solution do you need to add to make a butfer of pH 5.927 The pK, of acetic acid is 4.76 Number mL Previous 4 Check Answer Next Ext eers privacy polcy terms of usecontact usheip 15

Explanation / Answer

let be the number of moles of KOH= n moles

CH3COOH= 575 ml of 0.730M

number of moles of CH3COOH= 0.730M x0.575L= 0.41975 moles

CH3COOH    + KOH --------------------- CH3COOK    + H2O

0.41975                  n                             0

-n                           -n                           +n

0.41975-n                  0                          +n

Pka= 4.76

PH=5.927

PH= PKa + log[salt]/[acid]

5.927 = 4.76 + log(n/0.41975-n)

1.167 = log(n/0.41975-n)

(n/0.41975-n)= 10^1.167= 14.689

n= 6.139 - 14.689 n

n= 0.39 moles

number of moles of KOH= 0.39 moles

Concentration of KOH= 2.63

Concentration = number of moles/volume in L

volume in L= 0.39/2,63=0.148 L

volume of KOH= 148 mL

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