pH ml. l.OOON NaOH pH ml. l.OOON NaOH 



11.0 4.13 11.6 12.25 



11.2 6.00 11.8 16.65 



11.4 8.67 12.0 21.60 



McILVAINE BUFFERS 

 pH 2.2 - 8.0 

 Reference: J. Biol. Chem. _49_ 183 (1921) 



Stock Solutions : 



A) 0.500M Citric Acid: 



Weigh out 105.055 g. of dry Citric Acid (CgHgOy*H20) and dissolve 

 in enough water to make 1 liter. The Merck reagent grade, if taken 

 from a bottle freshly opened in the dry room, is satisfactory. To 

 be sure of the molarity, standardize with l.OOOM NaOH. The titration 

 is carried to a distinct red color of the phenolphthalein indicator. 



B) 0.500M Na2HP04: 



Weigh out 71.01 g. accurately and dilute to 1 liter with distilled 

 water in a volumetric flask. Freshly opened Merck Reagent or Baker's 

 analyzed grade chemicals may be used if kept in the dry room, but 

 for greater accuracy, dry in an oven for two hours at 120 C and 

 place in a desiccator. 



Buffers: 



To prepare 200 ml. of buffer, burette the amounts of stock solutions 

 indicated below into a 200 ml. volumetric flask, and dilute to the mark 

 with distilled water. 



ml. 0.500M Citric Acid 



39.20 

 37.52 

 35.64 

 33.66 

 31.78 



30.12 

 28.60 

 27.12 

 25.80 

 24.58 

 23.44 



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