Inorganic Chemistry

Test for purity of water

World consists of 70% water which coincides with the body’s water content and the pollution of water causes major health problems. By performing the above tests, it can be concluded that the water has passed the purity test.

Limit test for iron

BACKGROUND In this limit test, the iron reacts with thioglycollic acid in the presence of citric acid and in alkaline medium develops a pale pink to deep reddish purple colour due to the ferrous compounds might be present in the sample. As this test is very sensitive, citric acid 20% has been added which doesn’t … Read more

Limit test for lead

BACKGROUND The test as prescribed by B.P, the sodium sulphide reacts with lead salts to give a brownish colour solution and the intensity depends upon the amount of lead present in the sample, if the content of lead is high then it gives a colloidal brownish black precipitate of lead sulphide.1 Two solutions are prepared that … Read more

Limit test for sulphate

BACKGROUND The reagent used in the limit test for sulphate is barium sulphate and the comparison is done by observing turbidity of the test and standard solution, the soluble sulphate ion reacts with the barium chloride to form a white ppt as barium sulphate in the presence of dilute HCl. Barium sulphate reagent contains barium … Read more

Preparation of Potash Alum

BACKGROUND Potash alum is otherwise known as potassium aluminium sulphate which is mostly used in water purification, dyeing, leather tanning and inbaking powder. It forms regular octahedron crystals with flattened corners. Potash alum is soluble in water and it turns litmus paper red. Alums are prepared by adding the concentrated hot solutions of either potassium … Read more

Preparation of Boric Acid

BACKGROUND Boric acid occurs naturally in volcanic jets of steam. The crude boric acid crystallises on cooling. Commercially boric acid is prepared from sodium borate.1 Boric acid is prepared by treating borax with nitric acid and nitric acid is chosen over hydrochloric acid because sodium nitrate is more readily soluble than sodium chloride, and sulphuric acid … Read more

Preparation of Ferrous Sulphate

BACKGROUND Iron is a transitional element in periodic table. Iron compounds are used in medicine as an important constituent and the ores are widely distributed which includes haematite Fe2O3, limonite 2Fe2O3.3H2O, magnetic iron are Fe3O4. The earth’s core consists largely of iron. Iron shows two oxidation states – Ferrous and Ferric.1 Ferrous sulphate is otherwise … Read more

Limit test for arsenic

The IP prescribes limit test for arsenic as an impurity test for various drugs. The presence of arsenic in drugs even in traces is not desirable as it is toxic.