Please answer both parts, a previous chegger gave me the wrong answer! Thanks:)

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Please answer both parts, a previous chegger gave me the wrong answer!

Thanks:) i always upvote correct answers!

4/2/2018 11:59 PM A Gradebook 7.8/10 C Calculator 4/2/2018 08:22 PM Periodic Table Print Question 5 of 5 ncorrect Map Sapling Learning macmillan learning Calculate the pH of the following solutions a) A solution containing 0.0185 M maleic acid and 0.0257 M disodium maleate. The Ka values for maleic acid are 1.20 x 102 (Ka1) and 5.37 x10-7 (Ka2) Number pH-4.166 b) A solution containing 0.0377 M succinic acid and 0.024 M potassium hydrogen succinate. The Ka values for succinic acid are 6.21 x 10 (Ka ad 2.31 x10 (Ka2) Number pH-4.824 There is additional feedback available! View this feedback by clicking on the bottom divider bar. Click on the divider Incorrect bar again to hide the additional feedback Close Previous Give Up & View Solution # Try Again Next Exit Explanation

Explanation / Answer

Answer:

Ka = Ka1*Ka2 = 1.20 × 10-2 * 5.37 × 10-7 = 6.44 × 10-9.

pKa = -log(6.44 × 10-9) = 8.19.

Then pH is given by Henderson's equation as,

pH = pKa + log([Disodium maleate] / [Maleaic Acid])

pH = 8.19 + log(0.0257 /0.0185 )

pH = 8.19 + 0.14

pH = 8.05

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b) Here Pka1 = -logKa1 = -log(6.21*10-5) = 4.21

Then pH is,

pH = 4.21 + log(0.024 / 0.0377)

pH = 4.21 + (-0.20)

pH = 4.01

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