Question

A 458 gm sample of Mn3O4 was dissolved and all manganese was converted to Mn+2. In the presence of fluoride ion, Mn+2 I titrated with 3 lit. of KMnO4 solution (which was 1.25 N against oxalate in acidic medium), both reactant being converted to a complex of Mn(III)​

Answer 1

silica gel is common drying agent in the lab. Here, a Co(+2) complex is used to monitor the condition of silica gel. When it is charged, the colour is blue but when it absorbs moisture, color fades to light purple...