Calculating pH of a Buffer Solution with Added Strong Base

In summary, the conversation is about calculating the pH after adding 0.030 mol NaOH to a solution containing 1.00 L 0.100 M HC3H5O2 and 0.100 M NaC3H5O2. The equation used is the Henderson-Hasselbalch equation and the initial concentration of C3H5O2- is needed to calculate the correct pH.
  • #1
needphyshelp
21
0

Homework Statement


Calculate the pH after 0.030 mol NaOH is added to 1.00 L 0.100 M HC3H5O2 and 0.100 M NaC3H5O2


Homework Equations


Ka=[H+][A-]/[HA]
pH=-log([H+]) or 14-pOH=ph


The Attempt at a Solution


HC3H5O2 <-> H+ + C3H5O2-
NaC3H5O2 <-> Na+ + C3H5O2-

I know that Na+ has no acid/base properties, so I think that this equation is unimportant and I will be focusing on the first equation. I also know Kaeq1=1.3x10-5

I tried to set up an equilibrium equation, but I'm not sure if I should be completely ignoring the sodium equation.

1.3x10-5=(x2)/(.100-.030)
the numerator= [H+][C3H5O2-]

Any input would be appreciated...
 
Physics news on Phys.org
  • #3
Wouldn't that yield
pH=log(1.3e-5)+(.030/.1-.030) = 4.52? This answer is incorrect. Is there an initial concentration for C3H5O2- that I am missing?
 
  • #4
needphyshelp said:
0.100 M NaC3H5O2

needphyshelp said:
Is there an initial concentration for C3H5O2- that I am missing?

Yes.
 
  • #5
oh... duh..
thanks :-)
 

1. What is a buffer solution?

A buffer solution is a solution that resists changes in pH when small amounts of acid or base are added. It is made up of a weak acid and its conjugate base or a weak base and its conjugate acid.

2. How does a buffer solution maintain a constant pH?

A buffer solution maintains a constant pH by neutralizing any added acid or base with its conjugate base or acid, respectively. This maintains the ratio of acid to base, and therefore the pH, within the solution.

3. What is the purpose of using a buffer solution in experiments?

The purpose of using a buffer solution in experiments is to maintain a constant pH, which is necessary for many biological and chemical reactions. Without a buffer solution, small changes in pH could significantly affect the outcome of an experiment.

4. How does a strong base differ from a weak base?

A strong base completely dissociates in water, meaning all of its molecules break apart into ions. This results in a high concentration of hydroxide ions (OH-) in the solution. In contrast, a weak base only partially dissociates, resulting in a lower concentration of hydroxide ions.

5. Can a solution have a pH greater than 14?

No, a solution cannot have a pH greater than 14. This is because a pH of 14 represents a highly basic solution with a high concentration of hydroxide ions. Any further increase in hydroxide ions would result in a negative concentration of hydrogen ions, which is not possible.

Similar threads

  • Biology and Chemistry Homework Help
Replies
3
Views
1K
  • Biology and Chemistry Homework Help
Replies
7
Views
2K
  • Biology and Chemistry Homework Help
Replies
16
Views
2K
  • Biology and Chemistry Homework Help
Replies
4
Views
1K
  • Biology and Chemistry Homework Help
Replies
2
Views
1K
  • Biology and Chemistry Homework Help
Replies
2
Views
2K
Replies
2
Views
1K
  • Biology and Chemistry Homework Help
Replies
3
Views
2K
Replies
6
Views
3K
  • Biology and Chemistry Homework Help
Replies
16
Views
2K
Back
Top