Qualitative Tests on Antimony and Bismuth

Dilute 69 cm of purest syrupy phosphoric acid to 1 dm to obtain 1 M solution and by 10-fold dilution, prepare 0.1 M solution. Pipette 20.0 cm of the acid into a 250 cm conical flask. Calibrate the pH meter with a combined glass electrode and two buffer solutions at pH 4 and at 7. Dip the rinsed electrode into the flask, introduce a magnetic bar and add from a burette 0.1 M KOH solution in 2 cm aliquots, reading the pH on the meter when it settles. When the pH change becomes more rapid as the titration proceeds, decrease the volume down to 0.5 cm and then to 0.1 cm. After noting the first inflection point, continue with 2 cm additions of KOH and eventually to 0.1 cm addition until the second inflection point is reached. If a facility is available record the titration curve and preferably the derivative titration curve. 

Prepare 0.1 M solution of purest acid HP(OH 20 in water. Use a similar procedure as above and titrate using 0.1 M KOH solution. Note the total volume of alkali required for the two steps. Add this volume to a similar volume of acid used above and test a portion of the neutralised solution with silver nitrate solution. Draw your conclusions about the basicity of the acid. 

12 QUALITATIVE TESTS ON ANTIMONY AND BISMUTH 6.12.1 Antimony(lII) or antimonyfV) 

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