Preparation of hydrochloric acid extract

PREPARATION OF HYDROCHLORIC ACID EXTRACT

Principle

         A known weight of the soil is ignited to destroy the organic matter and the ignited soil is digested with hydrochloric acid to bring the mineral constitutents into solution.

Apparatus required

1.      250 mL conical flask

2.      Funnel

3.      All glass wash bottle

4.      500 mL volumetric flask

5.      100 mL  measuring cylinder

6.      Sand bath

Reagent required

         1:1 HCl

Procedure

Ø  Transfer the ignited soil of the previous experiment into a 250 mL conical flask using minimum quantity of water

Ø  Add 60 mL of 1:1 HCl , cover the mouth of the conical flask with a funnel and digest over a sand bath for about 8 hours.Add 200mL of water and keep it over night.

Ø  Filter through No.3 filter paper collecting the filtrate in a 500mL volumetric flask after smearing its mouth with a thin layer of Vaseline to prevent the solution from spilling.

Ø  Transfer all the soil into the filter paper and wash with hot water till the filtrate runs free of chloride.

Ø  Cool and make up the volume to 500 mL with cold distilled water.

Things to learn

1.      Why soil sample is ignited at 600  ?

2.      What is the chemical used in desiccators?

3.      What is the role of 1:1 HCl in nutrient extraction?