III. Buffer Solutions A. Buffer 1 i. Measure out 10.0 mL of 1.0 M CH 3 COOH and
ID: 905572 • Letter: I
Question
III. Buffer Solutions
A. Buffer 1
i. Measure out 10.0 mL of 1.0 M CH3COOH and 25.0 mL of 1.0 M sodium acetate (NaCH3COO) into a beaker
2. What is the concentration of acetic acid in this solution after mixing. (include units) [CH3COOH] ?
3. What is the concentration of acetate ion in this solution after mixing.(include units) [CH3COO-] ?
4. Calculate the expected pH of this buffer solution.
5. Measured pH of this buffer solution pH: 5.31
I have no idea how to do number 2,3,4 and I have to repeat these processes/ questions for different solutions. If you could show me how to do these, I would greatly appreciate it! Thank you so much in advance.
Explanation / Answer
2) . What is the concentration of acetic acid in this solution after mixing.
[CH3COOH] = millimoles of CH3COOH / total volume
= 10 x 1 / (10 +25)
= 0.286 M
[CH3COOH] = 0.286 M
3. What is the concentration of acetate ion in this solution after mixing
[CH3COO-] = millimoles of CH3COONa / total volume
= 25 x 1 / (10 +25)
= 0.714 M
[CH3COO-] = 0.714 M
4. Calculate the expected pH of this buffer solution.
millimoles of NaCH3COO = 25 x 1.0 = 25
millimoles of CH3COOH = 10 x 1.0 =10
this mixture is buffer
so
pH = pKa + log [CH3COONa ]/ [CH3COOH]
pH = 4.74 + log (25/10)
pH = 5.14