Question

The titration of Na2CO3 with HCl has the following qualitative profile: a. Identify the major species in solution at points A-F. b. Calculate the pH at the halfway points to equivalence, B and D. [Key

Answer 1

Answer:

Answer is explained in the explanation section below.

Explanation:

Solution:

Note: This question is incomplete and lacks very important data to solve this question. But I have found the similar question which shows the profiles about which question discusses. Using the data from that question, I have solved the question.

a) We need to find the major species from A to F.

Major Species at A:

1. $Na_{2} CO_{3}$

Major Species at B:

1. $Na_{2} CO_{3}$

2. $NaHCO_{3}$

Major Species at C:

1. $NaHCO_{3}$

Major Species at D:

1. $NaHCO_{3}$

2. $H_{2}CO_{3}$

Major Species at E:

1. $H_{2}CO_{3}$

Major Species at F:

1. $H_{2}CO_{3}$

b) pH calculation:

At Halfway point B:

pH = pK$a_{1}$ + log[$CO_{3}$$.^{-2}$]/[H$CO_{3}$$.^{-1}$]

pH = pK$a_{1}$ = 6.35

Similarly, at halfway point D.  

At point D,

pH = pK$a_{2}$ + log [H$CO_{3}$$.^{-1}$]/[H2$CO_{3}$]

pH = pK$a_{2}$ = 10.33