4.5.4.2.d Recrystallization of NH2OH.HCl: NH2OH.HCI crystals were dissolved in a minimum amount of rectified sprit by heating over steam bath and heating was continued for 2h and the solution allowed to cooling. The solid crystals of NH2OH.HCl formed were then filtered off by means of a suction pump. The residue was taken in a watch glass and then it was dried by inserting it in desiccators. Thus recrystallized NH2OH.HCl was obtained.
4.5.4.2.e Preparation of 0.5 (N) Hydroxylamine hydrochloride (NH2OH.HCl) Solution: About 9.0 g of recrystallized NH 2OH.HC1 was taken in a 250 ml volumetric flask and was dissolved in 219 ml of 60% ethanol. About 2–3 ml of bromophenol blue indicator was added to the solution. Then 0.5 N KOH alcoholic solution was added drop wise to make the solution greenish in colour, such that one drop of 0.5 (N) HCl solution would change the colour in to yellow. Then the resulting solution was made up to the mark of the volumetric flask with distilled water.
4.5.4.3 Standardization of alch. KOH by 0.5 (N) HCl: 10 ml of HCl was taken in a conical flask with the help of pipette. Few drops of 1% phenolphthalein added. The solution become colourless KOH solution was taken in a burette. KOH was added drop wish into the HCl solution. At the end of the titration the colourless solution became pink. The result is tabulated as follows:
Observe. no.
HCl solution (ml)
Burette reading , Volume of KOH solution (ml) IBR FBR Difference Average volume
1.
10
0.0
11.1
11.1
2.
10
11.1
22.2
11.1
3.
10
22.2
33.4
11.2
11.1