Adjusting the pH of a buffer solution

[Ezio]

Hi All,

 

I have a question about adjusting the pH of a buffer solution. I believe it is not correct to adjust the pH of any buffer by simply adding a few drops of HCl or NaOH, this would introduce a new ion into the solution if Na or Cl was not present in the original solution. Is this a correct philosophy or am I just being stupid?

 

Thanks all

[John Cuthber]

It will work, and it's quite comon practice. Ideally you might choose to use the same acid and base that the buffer is made from (e.g. for an ammonium citrate buffer you would use ammonia or citric acid). Also, ideally, you use a solution of the acid or bas that's the same molarity as the buffer but, most of the time, a bit of whatever acid or base you have handy will do.

It would make most difference if you needed to add a lot, in which case you haven't made a good choice of buffer in the firt place.

[Ezio]

Thanks for the reply.

 

I was thinking in the same direction, in terms of using the same acid or base the buffer was made from.

 

Thanks again