Finding the pH of a buffer solution when a strong acid is added

  • Thread starter Thread starter TheSwede
  • Start date Start date
  • Tags Tags
    Acid Buffer Ph
Click For Summary
SUMMARY

The discussion focuses on calculating the pH of a buffer solution containing 0.40 moles of propanoic acid and 0.50 moles of sodium propanate before and after the addition of a strong acid, HCl. The initial pH is calculated using the Henderson-Hasselbalch equation, yielding a pH of 4.75. When 3 milliliters of 2.0 M HCl is added, the concentrations of the weak acid and its conjugate base change, necessitating a reevaluation of the pH based on the new concentrations.

PREREQUISITES
  • Understanding of the Henderson-Hasselbalch equation
  • Knowledge of weak acids and their conjugate bases
  • Familiarity with pKa and Ka values
  • Basic concepts of buffer solutions and their behavior with strong acids
NEXT STEPS
  • Calculate the new concentrations of propanoic acid and sodium propanate after adding HCl
  • Reapply the Henderson-Hasselbalch equation to find the new pH
  • Explore the concept of buffer capacity and its limits
  • Study the effects of strong acids on various buffer systems
USEFUL FOR

Chemistry students, educators, and laboratory technicians involved in acid-base chemistry and buffer solution analysis.

TheSwede
Messages
1
Reaction score
0

Homework Statement



Three milliliters of a 2.0 M solution of HCL are added to 1 liter of buffer solution containing 0.40 moles of the weak acid, propanoic acid (Ka = 1.4 x 10-5) and .50 moles of its conjugate base, sodium propanate.

1) find the ph of the buffer solution

2) find the ph when the strong acid is added to the buffer solution

Homework Equations



Henderson Hasselbach equation: pH = Pka + log( A- / HA)

The Attempt at a Solution



1) to find the pKa -log(1.4 x 10-5) = 4.85
pH = 4.85 + log(.4/.5) = 4.75
is this correct?

2) clueless
 
Physics news on Phys.org
What happens when you add a strong acid? Is there any reaction taking place? How does it change concentrations of propanate and its conjugate acid?
 

Similar threads

Chemistry Moles of NaOH to Create Buffer Solution pH=6 in 0.42M Ethanoic Acid
  • · Replies 3 ·
Replies
3
Views
3K
Chemistry Solving pH Changes: Adding Acid to a Buffer or Water
  • · Replies 16 ·
Replies
16
Views
3K
Chemistry Understanding how to calculate pH of a buffer solution
  • · Replies 2 ·
Replies
2
Views
2K
Calculating the pH of a Buffer Solution
  • · Replies 7 ·
Replies
7
Views
4K
Chemistry Moles of a conjugate base in a buffer solution
  • · Replies 7 ·
Replies
7
Views
4K
Chemistry How to calculate pH at equivalence point using this alternative?
  • · Replies 7 ·
Replies
7
Views
2K
Chemistry Comparing methods of computing pH at equivalence point in titration
  • · Replies 4 ·
Replies
4
Views
2K
How Does Pre-existing CH3COONa Affect Buffer pH Calculation?
  • · Replies 4 ·
Replies
4
Views
2K
Max Buffering Capacity w/ 0.6 mol HAc & NaOH
  • · Replies 23 ·
Replies
23
Views
3K
Which formula to use to find the pH of a solution?
  • · Replies 20 ·
Replies
20
Views
3K