Clause 1. 4.1.15 Part -1
1. Standard EDTA Solution — 0.01 M. Dissolve 3.7224 g of
disodium ethylenediamine tetraacetate dihydrate in 400 ml hot water and make up
the volume in one-litre flask. Take 10 ml of standard zinc solution in an
Erlenmeyer flask. Add 20 ml buffer solution of pH 10 and warm to 50 to 60°C.
Add 50 mg Eriochrome Black-T indicator and titrate with EDTA till the colour
changes from wine red to clear blue. Note the volume of EDTA used ( V ).
Calculate the molarity of EDTA as follows:
2. Heat of Ignition
2. Heat
1.00 g of the sample for 15 minutes in a weighed and covered platinum crucible
(a porcelain crucible may also be used) of 20 to 25 ml capacity by placing it
in a muffle furnace at temperature between 900° and 1000°C; cool and weigh.
Check the loss in weight by a second heating for 5 minutes and re-weigh. Record
the loss in weight as the loss on ignition
Calculate the percent loss on ignition
as below:
Percent loss on ignition = loss in
weight × 100