Acid/Base Equilibrium - Buffers 1. A buffer solution of a weak acid and its salt

Question

Acid/Base Equilibrium - Buffers

1. A buffer solution of a weak acid and its salt had a pH of 4.04 when the acid was 0.183 M and the anion was 1.36 M. Calculate the equilibrium dissociation constant (Ka).

2. A solution of hydroxylamine/hydroxylammonium buffer contains 0.549 M HONH3Cl and has a pH of 5.51. Calculate the molarity of NH2OH in the solution. ( Kw=10-14 , Kb=1.10×10-8 )

NH2OH(aq) + H2O(l) = HONH3+(aq) + OH-(aq)

___________________M

3. A buffer solution with a pH of 6.03 has a molar ratio of anion to acid of 19.2. Calculate the equilibrium dissociation constant (Ka).

Explanation / Answer

There are multiple questions here . i am allowed to answer only 1 at a time. I will answer 2 for you since they are similar . Please ask other as different question.

1.
usE:
pH = pKa + log {[anion]/[acid]}
4.04 = pKa + log (1.36/0.183)
4.04 = pKa + 0.87
pKa = 3.17

Now use:
pKa = - log Ka
3.17 = -log Ka
Ka= 6.76*10^-4 M
Answer: 6.76*10^-4

3.
usE:
pH = pKa + log {[anion]/[acid]}
6.03 = pKa + log (19.2)
6.03 = pKa + 1.28
pKa = 4.75

Now use:
pKa = - log Ka
4.75 = -log Ka
Ka= 1.78*10^-5 M
Answer: 1.78*10^-5

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