NAME: JAIME VIEIRA RUIZ

SAMPLE: POTASSIUM CHLORIDE

1)      IDENTIFICATION REACTIONS OF IONS

-          CATIONS (describe briefly reactions):

A) K^+ + Na[2]CO3 à no precipitate
K^+ + Na[2]S à no precipitate
K^+ + tartaric acid à white crystalline precipitate

B) Na[2][Co(NO[2])[6]] + 2K^+ à K[2]Na[Co(NO[2])[6]] + 2NA^+ à KNa[2][Co(NO[2])[6]] (Yellow
precipitate) or K[3][Co(NO[2])[6]] (orange-yellow precipitate)

-          ANIONS (describe briefly reactions):

A) Cl^- + Ag^+ à AgCl (curdled, whit precipitate is formed)
AgCl + NH[3] à [Ag(NH[3])[2]] + Cl^- (precipitate dissolves easily)

B) 4Cl^- + K[2]Cr[2]O[7 ]+ 6H^+ à 2CrO[2]Cl[2 ]+ 3H[2]O
Paper impregnated with diphenylcarbazide solution turns violet-red.

2)      ASSAY: BACK TITRATION

Volumetric solutions: Silver nitrate and ammonium thiocyanate

Titre of volumetric solutions: 0,1 M AgNO[3 ]= 0,9998; 0,1M NH[4]SCN= 0,9897

                                           Titration No.

                                     m [g] (4 decimal places)

                                      Consumption of VS [ml]

                                               ASSAY

                                                1.

                                              1,2926

                                               7,95

                                               98,84

                                                2.

                                              1,2784

                                               7,69

                                              101,44

                                                3.

                                              1,3154

                                               7,56

                                               99,32

                                                4.

                                              1,2847

                                               7,68

                                             101,0041

                                                                                            Average

                                              100,151

CALCULATION PROCEDURE:


STATISTICAL EVALUATION:

Range:
      R = 2,1641

Standard deviation (estimated from range):                         sd = 1,0511

Relative standard deviation:                                                        RSD = 1,049

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

The sample meet Ph.Eur, because the average is between 99.0 – 100.5% of KCl