Please answer each question on a seperate post so I can rate youproperly. (Answe

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Please answer each question on a seperate post so I can rate youproperly.

(Answers in bold, need explanation or at least work, not homework,just need to understand them)

15) Ka/Kb

a) What is the equilibrium constant for the neutralization reactionof HClO with a KOH
solution at 25°C? (Ka for HClO is 3.0 × 10–8)
HClO(aq) + KOH(aq) KClO(aq) + H2O(l)

Ans: 3.0 × 106

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b) Given that for carbonic acid, H2CO3, Ka1 = 4.3 ×10–7 and Ka2 = 5.6 × 10–11, calculate the
pH of a solution formed by mixing 50 ml of 0.20 M NaHCO3 and 50 mlof 0.20 M
Na2CO3.
Ans: 10.25
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c) Citric acid, which we denote as H3A, is a triprotic acid withKa1 = 7.4 × 10–4, Ka2 = 1.7 ×
10–5 and Ka3 = 4.0 × 10–7. What is the pH of asolution prepared by dissolving 0.100
moles of Na3A (the sodium salt of A3–) in 1 liter ofwater?

Ans: 9.70
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Explanation / Answer

We Know that :      b.             The second Question is based on the buffer problem :          According toHenderson's - Hasselbalch equation :          pH = pKa + log [ salt ] / [ Acid]                  = 10.25 + log [ Na2CO3 ] / [ NaHCO3 ] We have to take Ka2 as the second hydrogen from Bicarbonate                                                                                          is replaced.                   = 10.25 + log [ 0.050 x 0.20 ] / [ 0.050 x 0.20 ]                    = 10.25         

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