Question

How will you prepare a colloidal solution of egg albumin in water? Give one precaution to be observed.​

Answer 1

Theory

Egg albumin which is obtained from eggs forms lyophilic sol with cold water. The sol is quite stable and is not affected by the presence of traces of impurities.

♥ ♥ ♥

Materials Required

Beakers (250 ml and 50 ml), glass rod, funnel, filter-paper, pestle and mortar, tripod stand, wire-gauze and burner, Soluble starch (500 mg) and distilled water.

♥ ♥

Procedure

• Break the outer shell of the egg by striking it with a glass rod and collect its colour less liquid along with yellow yolk. Decant the colourless liquid into another beaker. This colourless liquid is known as egg albumin.
• Prepare 100 ml of 5% (w/v) solution of sodium chloride in a 250 ml beaker. To this solution add egg albumin in small portions with constant stirring. This process should take 15-20 minutes.
• Filter the contents of the beaker through a filter paper, fixed in a funnel, and collect f the filtrate. Label this filtrate as ‘egg-albumin sol’.

♥ ♥ ♥

Precautions

• e apparatus used for preparing the sol should be absolutely clean.
• The stilled water should be used for preparing the sol.
• gg albumin sol is prepared at room temperature because in hot solution the precipitation of egg albumin takes place.
• he yellow yolk should be separated completely from the egg albumin before using the latter in the experiment.
• Addition of egg albumin should be done very slowly and with constant stirring so as to disperse the colloidal particles well in solution.