# I really need help with this question

## Recommended Posts

Use the Henderson-Hasslebalch equation to calculate the volume of 0.20M NaOH required to adjust the pH of the 0.10M acetic acid solution to the pKa value of acetic acid. Note: you will first need to calculate the number of moles of NaOH and then use the concentration of the NaOH to determine the corresponding value.

I do not understand where to start since to find number of moles of NaOH you need the volume but the volume was not given.

##### Share on other sites

I do not understand where to start since to find number of moles of NaOH you need the volume but the volume was not given.

Have you read the question carefully, it ask you to find the volume? Let me give you a little push use V as the volume and do all the calculation.

Show us a little work of yours so that we can help you!

##### Share on other sites

Use the Henderson-Hasslebalch equation to calculate the volume of 0.20M NaOH required to adjust the pH of the 0.10M acetic acid solution to the pKa value of acetic acid. Note: you will first need to calculate the number of moles of NaOH and then use the concentration of the NaOH to determine the corresponding value.

I do not understand where to start since to find number of moles of NaOH you need the volume but the volume was not given.

pH = pKa + log to base 10 ([A-]/[HA])

where [HA] is the molar concentration of the undissociated weak acid and [A-] is the molar concentration of the acid's conjugate base

pKa = -log to base 10 (Ka)

where Ka is the acid dissociation constant

i.e. pKa = -log to base 10 (([H30+] + [A-])/[HA])

The reaction:

Sodium hydroxide + acetic acid -> sodium acetate + water

NaOH + CH3COOH -> CH3COONa + H20

pH = -log [H+]

pKa = pH (the equivalence point) when exactly 1/2 of the acid has dissociated

pKa (acetic acid) = 4.76

Here is a useful resource by Wiley Essential Biochemistry, for understanding pH, features self-test exercises and animations: http://www.wiley.com/college/pratt/0471393878/student/review/acid_base/index.html

Edited by Tridimity

## Create an account

Register a new account