NAME: Guidevaux Aurélia

SAMPLE: Potassium Bromide

1)      IDENTIFICATION REACTIONS OF IONS

-          CATIONS (describe briefly reactions):

Potassium cation K+

KBr(aq) + AgNO[3](aq) → AgBr(s) + KNO[3](aq)

Dissolve 0,1g of the substance to be examined in 2 mL of water R or use 2mL of the prescribed
solution. Add 1mL of sodium carbonate solution R and heat. No precipitate is formed.

Add to the hot solution 0,05mL of sodium sulfide solution R. no precipitate is formed. Cool in iced
water and add 2mL of a 150g/L solution of tartaric acid R. allow to stand.

A white crystalline precipitate is formed

Dissolve about 40mg of the substance to be examined in 1mL of water R or use 1mL of the prescribed
solution.

Add 1mL of dilute acetic acid R and 1mL of a freshly prepared 100g/L solution of sodium
cobaltinitrite R.

A yellow or orange-yellow precipitate is formed immediately.



-          ANIONS (describe briefly reactions):

Bromide anion Br-

Dissolve in 2 mL of water R a quantity of the substance to be examined equivalent to about 3mg of
bromide or use 2 mL of the prescribed solution.

Acidify with dilute nitric acid R and add 0,4mL 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 1mL 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 1,5mL 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.

1.8954

16.02

57,38

                                                2.

2.0045

15.63

56,55

                                                3.

2.0215

15.32

57,88

                                                4.

1.9854

15.34

58,82

                                                                                            Average

57,66

CALCULATION PROCEDURE:



STATISTICAL EVALUATION:

Range:
      R = 2,27

Standard deviation (estimated from range):                         sd = 1,10

Relative standard deviation:                                                        RSD = 1,91


CONCLUSION (does your sample meet/not meet Ph. Eur): My sample doesn’t meet Ph.Eur