Login or Sign Up
Menu
Ask a New Question

(ii) between 0 and 100.0 mL NaOH added

H2A
H2O
HA -
Na+
A2-
OH -

(iii) 100.0 mL NaOH added
H2A
H2O
HA -
Na+
A2-
OH -

(iv) between 100.0 mL and 200.0 mL NaOH added
H2A
H2O
HA -
Na+
A2-
OH -

(v) 200.0 mL NaOH added
H2A
H2O
HA -
Na+
A2-
OH -

(vi) after 200.0 mL NaOH added
H2A
H2O
HA -
Na+
A2-
OH-

Sorry, I forgot the question. For the following volumes of NaOH added, list the major species present after the OH - reacts completely.

I feel like I'm always missing something. For example, I thought (ii) was H2A HA- OH - and H2O,but it was wrong

This can't be answered without a concn of NaOH.

The [NaOH] was never given in the question. Only the total mL.

I think ii is H2A, HA^-, H2O, Na^+.

Dr. Bob, you are amazing.I was completely stuck. Thank you so much!

To determine the species present at each stage when NaOH is added to a solution, we need to consider the acid-base reactions that occur. Let's break down each stage and identify the species at each point:

(ii) between 0 and 100.0 mL NaOH added:
At the beginning, before any NaOH is added, we have the following species:
H2A, H2O, HA-, Na+, A2-, OH-

When NaOH is added, it reacts with the acidic species present in the solution, which is the H2A. The reaction is as follows:
H2A + NaOH -> HA- + H2O

So at this stage, the species present are:
H2O, HA-, Na+, A2-, OH-

(iii) 100.0 mL NaOH added:
When 100.0 mL of NaOH is added, the reaction continues as follows:
HA- + NaOH -> Na+ + A2- + H2O

Now the species present are:
H2O, Na+, A2-, OH-

(iv) between 100.0 mL and 200.0 mL NaOH added:
As more NaOH is added, it continues to react with the remaining HA- species:
HA- + NaOH -> Na+ + A2- + H2O

The species present now are:
H2O, Na+, A2-, OH-

(v) 200.0 mL NaOH added:
When 200.0 mL of NaOH is added, the reaction completes with the conversion of HA- to A2-:
HA- + NaOH -> Na+ + A2- + H2O

So at this stage, the species present are:
H2O, Na+, A2-, OH-

(vi) after 200.0 mL NaOH added:
After 200.0 mL of NaOH is added, all the HA- has been converted into A2-, and there are no more acidic species to react with NaOH. Therefore, the species present remain the same as in stage (v):
H2O, Na+, A2-, OH-