Respuesta :
Answer:
You have to add 285.642 mL of KH2PO4
Explanation:
Step 1: What is a buffer
A buffer is a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. Buffers work by reacting with any added acid or base to control the pH.
pH of a buffer = pKa + log [conj base] / [weak acid]
Step 2: The ph of the buffer
6.97 = 7.21 =log [K2HPO4] / [KH2PO4]
-0.24 = log [K2HPO4] / [KH2PO4]
10 ^ -0.24 = [K2HPO4] / [KH2PO4] = 0.5754
0.5754 = (0.450 - x) / x
0.5754x = 0.450 - x
1.5754x = 0.450 L
x = 0.28564 = volume of KH2PO4
0.450 - 0.28564 = 0.16436 L K2HPO4
You have to add 285.642 mL of KH2PO4
The study of chemicals and bonds is called chemistry.
The correct answer is 285.642 mL of KH2PO4
What is a buffer solution?
- A buffer is a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid.
- Buffers work by reacting with any added acid or base to control the pH.
What is the formula to solve this question?
- pH of a buffer = [tex]pKa + log \frac{[conj \ base]}{ [weak\ acid]}[/tex]
All the data is given in the question. placed them in the equation and solve the question.
[tex]6.97 = 7.21 =log \frac{[K2HPO4] }{[KH2PO4]}\\-0.24 = log \frac{[K2HPO4]}{ [KH2PO4]}10 ^ {-0.24} = \frac{[K2HPO4]}{ [KH2PO4]} = 0.5754\\0.5754 = \frac{(0.450 - x)}{x}[/tex]
[tex]0.5754x = 0.450 - x1.5754x = 0.450 Lx = 0.28564 = volume \ of\ KH2PO40.450 - 0.28564 = 0.16436 L \ K2HPO4[/tex]
You have to add 285.642 mL of KH2PO4 to make the solution.
Hence, the correct answer is 285.642.
For more information, refer to the link:-
https://brainly.com/question/10038290
