Each of the following statements concerns a 0.10 M solution of a weak organic ac

Question

Each of the following statements concerns a 0.10 M solution of a weak organic acid, HA. Determine whether each statement is true or false, and explain the basis for your answer.

a) [HA] is approximately equal to 0.10 M.
(I think this is true based on what I know about ICE tables,but Im not sure?)

b) [HA] is much greater than [A-]
(I think this true, because isnt A- a product of the decomposition of the acid, and therefore smaller than the whole?)

c) [OH-] is greater than [A-]
(I have no idea on this one)

d) The pH is 1
(This is false because the acid is weak and could never therefore be 1, right?]

e) [A-] is approximately equal to [H3O+]
(No idea again)

f) [H3O+] equals 0.10 M.
(I think this one might be true but I cant fully explain why?)

Thank you so much Chegg tutors! I just feel really lost on acid-base and ICE tables, so this will help me out a lot!

Explanation / Answer

(a)

[HA] is approximately equal to 0.10 M. true

As it is weak acid and [HA] is concentration of acid. And weak acid does not dissociate completely. [HA] is approximately equal to 0.10 M

(b)

[HA] is much greater than [A-]. True

As weak acid does not dissociate completely [HA] should remain in the solution and definitely [A-] will be less.

(c)

[OH-] is greater than [A-] False

This OH- comes from water.

Kw = H2O ßà H+ + OH- = 1*10^-14 M

But water hardly ionizes and stays as water only.

(d) The pH is 1 False

Weak acid of 0.1 M has 0.001 M H3O+( dissociation of only 1% of 0.1M) and pH of approximately 3.

Strong acid like HCl may have pH of 1 but not weak acids.

(e) [A-] is approximately equal to [H3O+] True

[H3O+] is concentration [H+].

As acid dissociates, even partially.

HA ßà H+ + A- = H3O+ + A-

Therefore, concentration of both species may remain approximately same.

(f) [H3O+] equals 0.10 M. False

Weak acids never dissociate completely. Therefore, [H3O+] having the concentration of 0.1 M is not possible. It may have concentration of 0.001M

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