PH and Molarity of a Buffer

[ReidMerrill]

For a lab I need to create a 0.1M solution of NaOAc buffer at pH 5
It's been a while since I worked with buffers. I'm struggling to find a way to get both the proper morality and proper pH.
My first though was to create a 0.2M solution of acetic acid and titrate it to pH 5 using sodium hydroxide. The problem is when I tried to calculate the pH of 0.2M solution of acetic acid I got a pH higher than 5 so I couldn't use sodium hydroxide to adjust the pH. I think this was a calculation error on my part though.

Any help would be greatly appreciated.

 

[Borek]

Check this out: http://www.chembuddy.com/?left=buffers&right=toc

Yes, your calculation of pH is faulty, as pH of 0.2 M acetic acid is below 3.

 

[ReidMerrill]

Check this out: http://www.chembuddy.com/?left=buffers&right=toc

Yes, your calculation of pH is faulty, as pH of 0.2 M acetic acid is below 3.

I did some Google snooping and apparently the pH of a 0.1M solution of acetic acid is 2.88.

In that case, how do I raise the pH without lowering the molarity?

 

[Borek]

There are worked out examples at the link provided, why don't you check them?

 

[symbolipoint]

For a lab I need to create a 0.1M solution of NaOAc buffer at pH 5
It's been a while since I worked with buffers. I'm struggling to find a way to get both the proper morality and proper pH.
My first though was to create a 0.2M solution of acetic acid and titrate it to pH 5 using sodium hydroxide. The problem is when I tried to calculate the pH of 0.2M solution of acetic acid I got a pH higher than 5 so I couldn't use sodium hydroxide to adjust the pH. I think this was a calculation error on my part though.

Any help would be greatly appreciated.

You COULD actually do the titration to determine, ultimately how to prepare your pH 5 buffer, as long as you carefully record how much of what concentrations of the solutions you used, as as long as you properly calibrated your pH meter before doing the titration. You should be able to figure how much sodium acetate is present once you reached pH 5. (This should be a beginner's lab exercise.)