Explore BrainMass
Share

Calculations: Buffer Solution Preparation

This content was STOLEN from BrainMass.com - View the original, and get the already-completed solution here!

Acetic acid is a good choice to make buffers that are moderately acidic because it is easy to use, inexpensive, and the ions do not interact strongly with most biomolecules. The pKa of acetic acid is 4.75. We want to prepare 1.5 L of buffer at pH = 5.25 that is approximately 50 mM in concentration. You have the following solutions available to use (and only these):
0,050 M acetic acid
2.0 M NaOH
2.0 M HCl

What will you mix using the above stock solutions to make your buffer? Before you begin any calculations, explain your strategy and any assumptions you make. After you calculate the required volumes, calculate the actual final pH, volume, and concentration of each species in solution. (Hint: There should be five solutes present at equilibrium).

Please show work till final calculation as I am really stuck.

© BrainMass Inc. brainmass.com October 25, 2018, 9:08 am ad1c9bdddf
https://brainmass.com/chemistry/acid-base-neutralization/calculations-buffer-solution-preparation-565045

Solution Preview

Answer to 565045

Acetic acid is a good choice to make buffers that are moderately acidic because it is easy to use, inexpensive, and the ions do not interact strongly with most biomolecules. The pKa of acetic acid is 4.75. We want to prepare 1.5 L of buffer at pH = 5.25 that is approximately 50 mM in concentration. You have the following solutions available to use (and only these):
0,050 M acetic acid
2.0 M NaOH
2.0 M HCl
What will you mix using the above stock solutions to make your buffer? Before you begin any calculations, explain your strategy and any assumptions you make. After you calculate the required volumes, calculate the actual final pH, volume, and concentration of each species in solution. (Hint: There should be five solutes present at equilibrium).
Please show work till final calculation as I am really stuck.

*******************

General guideline
Many buffer problem involves a determination of the ratio of the [salt] to [acid] and the total of the [salt] and [acid]. Let,
[salt] / [acid] = a
[salt] + [acid] = b
It is essential in any buffer problem to identify from the given description the values of pKa, pH, a, and b, which can ...

Solution Summary

Starting with a general guideline and then coming to the specific problem, this solution contains step-wise calculations for preparing a buffer solution.

$2.19
See Also This Related BrainMass Solution

Calculate the pH for a buffer solution.

Calculate the pH for a buffer solution prepared by mixing 100. mL of 0.60 M NH3 and 200. mL of 0.45 M NH4Cl.

The Ka of NH4 + = 5.6 x 10^-10.

a) 8.65
b) 9.08
c) 9.87
d) 4.90
e) 6.62

View Full Posting Details