Question 9 What is the molar concentration of acetic acid [HA] and acetate [A-]

Question

Question 9 What is the molar concentration of acetic acid [HA] and acetate [A-] in a 02 M solution of acetate at pH 5.0? pKa -4.76 O 0.072 M acetic acid, 0.128 M acetate O 0.1 M acetic acid, 0.1 M acetate O 0.026 M acetio acid. 0.174 M acetate O 0.2 M acetic acid, 0.2 M acetate Question 10 Which one of the following statements is NOT true? Phosphoric acid has three dissociable protons Phosphoric acid is a good physiolggical buffer because the pKa of one of its di The pti of blood-is primarily buffered by phosphorke ad Buffeis are'uritica for maintainis the pl lnsds ra

Explanation / Answer

1.) ANSWER:

Given,

[solution] = 0.2 M

pH = 5.0

pKa = 4.76

According to Handerson-Hasselbalch equation:

pH = pKa + log{[A-] / [HA]}

5.0 = 4.76 + log{[A-] / [HA]}

log{[A-] / [HA]} = 0.24

{[A-] / [HA]} = 1.74

Here, only first option gives this value i.e. {[0.128] / [0.072]} = 1.74

Hence, option first is correct.

2.) ANSWER:

Since, phosphoric acid is very week acid so all protons are not easily dissociable. So, option first is not correct. Except this all option are correct about phosphoric acid.

Hence, option first is answer.

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