# Need Help With Buffers: Test on Tuesday!

• STAR3URY
In summary, buffers resist drastic changes in pH and the H+ ion concentration in a buffer solution is determined by Ka or Kb, the concentration of the acid or alkali, and the concentration of the salt. To find the pH of a buffer, use the equation pH = -lg [H+].
STAR3URY
Very Urgent: Need Help With Buffers!

I have a test coming up on Tuesday and I have no idea how to do buffers, I don't understand what Value of the Ka we are suppose to use from the chart. I get the equation a little bit: [H+]= Ka x moles HB/moles of B-

What? Your problem description and question are poor. What are your knowns and what are you unknowns?

ok... i'll try to help you out a bit...

you should know that buffers resist drastic change in pH.

basically, the H+ ion concentration in a buffer solution is:

Ka * [acid] / [salt]

or for an alkaline buffer

Kb * [alkali] / [salt][acid] would mean the concentration of the acid in mol/dm3

if you use ethanoic acid and sodium ethanoate as the buffer, then H+ concentration is

dissociation constant of ethanoic acid * concentration of ethanoic acid / concentration of sodium ethanoate

the question will usually ask you about the pH of the buffer. to get the pH:

pH = -lg [H+]

## What is a buffer?

A buffer 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.

## Why do we use buffers?

Buffers are used to maintain a stable pH in a solution. This is important in many biological processes, as well as in chemical reactions where pH can affect the outcome.

## How do buffers work?

Buffers work by utilizing the principle of Le Chatelier's principle. When an acid or base is added to a buffer solution, the equilibrium of the weak acid/base and its conjugate is shifted to maintain a relatively constant pH.

## How do you prepare a buffer solution?

A buffer solution can be prepared by mixing a weak acid or base with its conjugate salt. The ratio of acid to base will depend on the desired pH and the acid dissociation constant (Ka) of the weak acid or base.

## What factors can affect the effectiveness of a buffer?

The effectiveness of a buffer can be affected by changes in temperature, dilution, and the presence of other ions that may react with the weak acid or base. It is important to choose a buffer with a pKa close to the desired pH to ensure maximum effectiveness.

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