Question

I am doing triprotic acid titrations.

I have an imaginary acid (H3A) 10mL with the concentration 0.760M and we are titrating a NaOH with the concentration of 0.320M.

I have to find the amount of NaOH in mol and mL for

1. first half-equivalence point

2.first equivalence point

3. second-half equivalence point

4.second equivalence point

5. third half-equivalence point and

6. third equivalence point.


and then I have to find the pH for each of these points.

Answer 1

n(NaOH)=(0.76/100)/(2/№point)

V(NaOH)=n/0.00320

1. n = 0.0038; V = 11.88;
2. n = 0.0076; V = 23.75;
3. n = 0.1140; V = 35.63;
4. n = 0.1520; V = 47.50;
5. n = 0.1900; V = 59.37;
6. n = 0.2280; V = 71.25;

pH for every point: pH=-lg(C_H3AK₁+C_H2A+K₂+C_HAK₃)^1/2