NAME: Felix Saber

SAMPLE: Potassium Bromide

1)      IDENTIFICATION REACTIONS OF IONS

-          CATIONS (describe briefly reactions):

Solutions S gives the reactions of potassium

-          Dissolve 0.1 g of the substance to be examined in 2 mL of water R or use 2 mL of the
prescribed solution. Add 1 mL
of sodium carbonate solution R and heat. No precipitate is formed. Add to the hot solution 0.05 mL
of sodium sulfide solution R. No precipitate is formed. Cool in iced water and add 2 mL of a 150
g/L solution of tartaric acid R. Allow to stand. A white crystalline precipitate is formed.

-          b) Dissolve about 40 mg of the substance to be examined in 1 mL of water R or use 1 mL
of the prescribed solution. Add 1 mL of dilute acetic acid R and 1 mL of a freshly prepared 100 g/L
solution of sodium cobaltinitrite R. A yellow or orange-yellow precipitate is formed immediately.


-          ANIONS (describe briefly reactions):

-          Dissolve in 2 mL of water R a quantity of the substance
to be examined equivalent to about 3 mg of bromide (Br–) or use 2 mL of the prescribed solution.
Acidify with dilute nitric acid R and add 0.4 mL of silver nitrate solution R1. Shake and allow to
stand. A curdled, pale yellow precipitate is formed. Centrifuge and wash the precipitate with three
quantities, each of 1 mL, of water R. Carry out this operation rapidly in subdued light
disregarding the fact that the supernatant solution may not become perfectly clear. Suspend the
precipitate obtained in 2 mL of water R and add 1.5 mL of ammonia R. The precipitate dissolves with
difficulty.

2)      ASSAY

Volumetric solutions: 0,1 M AgNO3

Titre of volumetric solutions: 0.9998

                                           Titration No.

                                     m [g] (4 decimal places)

                                      Consumption of VS [ml]

                                               ASSAY

                                                1.

2.0014

8.45

98.866

                                                2.

2.1054

7.89

97.139

                                                3.

2.0456

8.38

97.157

                                                4.

1.9985

8.34

99.683

                                                                                            Average

98.211

CALCULATION PROCEDURE:

X1=(25x0.9998-8.45x0.9897)x11.90x100/200.19=98.866

X2=(25x0.9998-7.89x.09897)x11.90x100/210.54=97.139

X3=(25x0.9998-8.38x0.9897)x11.90x100/204.56=97.157

X4=(25x0.9998-8.34x0.9897)x11.90x100/199.85=99.683

= 98.211



STATISTICAL EVALUATION:

Range:
      R = 2.544

Standard deviation (estimated from range):                         sd = 1.2722563617452

Relative standard deviation:                                                        RSD = 1.30%




CONCLUSION (does your sample meet/not meet Ph. Eur):  yes