Posted by **Remy** on Tuesday, November 29, 2011 at 11:01pm.

Consider the titration of the weak acid HA with NaOH. At what fraction of Ve does pH = pKa - 1? At what fraction of Ve does pH = pKa + 1? Calculate the pH at these two points plus Vb = 0, 1/2Ve, Ve and 1.2Ve, if 100 mL of 0.100 M anilinium bromide (pKa = 4.601) is titrated with 0.100 M NaOH. {Ve is Volume at equilibrium,Vb is volume of base}

- Chemistry help!! -
**DrBob222**, Wednesday, November 30, 2011 at 12:07am
Surely you mean Ve = volume at the equivalence point.

The Henderson-Hasselbalch equation is

pH = pKa + log(base)/(acid)

If pH = pKa, then log B/A = 0 and B/A = 1

If pH = pKa + 1, then log B/A = 1 and B/A = 10

If pH = pKa -1, then log B/A = -1 and B/A = 0.1

..........HA + OH^- ==> A^- + H2O

initial....1.....0.......0......0

add.............x..............

change.....-x....-x......x.....x

equil.....1-x.....0......x.....x

The three cases above are done this way.

When B/A = 1, then [(x)/(1-x)] = 1

Solve for x and obtain x = 1-x so you are half way to the equivalence point.

When B/A = 10, then [(x)/(1-x)]=10

Solve for x = 0.90909 and that is the fraction to Ve.

When B/A = 0.1, then......

Set up an ICE chart and substitute moles into it for base and acid and use the HH equation to solve for pH for the specific points.

Post your work if you get stuck.

## Answer This Question

## Related Questions

- Analytical Chemistry 2 - Consider the titration of the weak acid HA with NaOH. ...
- Chemistry - Part A: Unknown Acid use 1gram and mix with 120 mL of distilled ...
- Chemistry - Consider a weak acid-strong base titration in which 25.0 mL of 0.100...
- Chemistry - 100 mL of 1.0 M formic acid (HCOOH) is titrated with 1.0 M sodium ...
- chemistry- titration - Once you have calculated your Ka value, use the data to ...
- CHEMISTRY - In the analysis of food, the nitrogen from the protein is sometimes ...
- college chemistry - In the analysis of food, the nitrogen from the protein is ...
- chemistry - titration - Show that for the titration of a weak acid, HA, with ...
- chemistry - You discovered a new diprotic acid, which you have named edmontonic...
- CHEMISTRY FOR DR. BOB or anyone else - A hypothetical weak acid HA, was combined...

More Related Questions