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Non Life Sciences => Chemistry => Topic started by: violet on 25/01/2004 17:26:12

Title: How do I prepare a phosphate buffer with constant ionic strength?
Post by: violet on 25/01/2004 17:26:12

Hello everybody,

I need a information how to prepare phosphate buffer from phosphoric acid and natrium hydroxide with pH 2,8;  3,3;  3,8;  4,3;  4,8;  5,3; and 5,8. The ionic strength must be 0,01M.
There are many instruction how to prepare phosphate buffers, but no mention about ionic strength.

My calculation:
For 250 ml of phosphate buffer with pH 2,8 we need mix 14,9 ml 0,1 M H3PO4 and 12,2 ml 0,1 M NaOH (ionic strength is now 0,01159M). For ionic strength 0,01M we have to dilute solution 1,159 times. Net volume is then 289,75 ml.
Is it correct?

Thank You.