In this article, we will discuss the procedure to perform an experiment that will help us understand how to prepare a colloidal solution of Egg albumin. Before starting the experiment let’s first understand What is a colloid mixture or colloidal solution in Chemistry?
Colloidal solutions or Colloids are the mixtures in which microscopically insoluble particles of one substance are suspended in another substance. Not all the mixtures are colloids. The mixture where suspended particles don’t settle down at the bottom but get evenly dispersed into another substance. The size of the colloids ranges from 1 nm to 1000 nm. One important class of colloidal systems is sols. In sols, the dispersed phase is a solid medium, and the dispersion medium is liquid in the state, and depending upon the nature of the interaction between the dispersed phase and dispersion medium sols can be broadly classified into two types.
Lyophilic Sols: The term lyophilic means ‘liquid-loving’ or ‘solvent- attracting’, which means in this colloidal solution there is a strong affinity towards the dispersed phase and the dispersion medium.
Lyophobic sols: The term lyophobic means ‘liquid-hating’, which means in these sols, there is little or no interaction between the dispersed phase and the dispersion medium i.e., a dispersed phase has little affinity for dispersion medium.
Egg albumin obtained from eggs form a lyophilic sol with cold water. The sol is stable in nature and not affected by the presence of traces of impurities. Now let’s discuss the procedure.
To prepare a colloidal solution (lyophilic sol) of egg albumin.
Lyophilic sol can be obtained from egg albumin present in eggs. When the egg albumin is mixed with cold water lyophilic sol is obtained. The sol obtained is stable and is not affected by the impurities present in it. Egg albumin formula : C16H26O5
Beakers (250 ml and 50 ml)
Soluble starch (500 ml)
pestle and mortar
Break the outer shell of the egg with the help of a glass rod, and collect the colorless liquid (albumin water) and yellow part, decant the colorless liquid in another beaker.
In a beaker of 250 mL prepare 100 mL NaCl solution of 5% (w/v). Pipette out the albumin and pour it into the beaker containing sodium chloride solution by doing constant stirring for 15-20 mins, ensure that the sol is prepared well and egg albumin in water forms.
Now, filter the contents of the beaker with the help of filter paper and funnel and label the filtrate as egg albumin sol.
The apparatus used for the experiment should be properly cleaned.
Separate both the egg albumin water and yellow yolk before mixing it with sodium chloride solution.
Stir the mixture constantly in the beaker while adding egg albumin to prepare egg albumin sol.
Make sure egg albumin sol is prepared at room temperature because precipitation of egg albumin takes place in a hot solution.
Distilled water should be used to prepare egg albumin sol. (Egg albumin in water forms colloid)
The common method to classify colloids is based on the phase of the dispersed substance and dispersion medium. Different types of colloids are sol, emulsion, foam, aerosol, and gel.
Sol is a colloidal system in which the dispersed phase is solid, and the dispersion medium is liquid. Eg: Blood, Ink, Paint, Mud, etc.
An emulsion is a colloidal system in which the dispersed phase is liquid and the dispersion medium is another liquid. Eg: Milk, Salad dressing, Brewed coffee.
Foam is a colloidal system in which the dispersed phase is gas, and the dispersion medium is solid or liquid. Eg: Whipped cream, Bubble bath, Fire retardant, etc.
An aerosol is a colloidal system in which the dispersed phase is a liquid or solid particle, and the dispersion medium is gas. Eg: Hairspray, Perfume, Mist, Fog, etc.
The gel is a colloidal system in which the dispersed phase is solid and the dispersion medium is liquid. Eg: Toothpaste, Jam, Cheese, Rubber, Gelatin, etc.
Mayer’s albumin preparation contains the following except-
a.) Sodium Chloride
d.) Egg white
Answer: Option (a) Sodium Chloride.
Mayer’s albumin preparation does not contain Sodium Chloride.
2. How do you differentiate between egg yolk and egg albumin?
The yellow color present in the egg is called egg yolk. It gets its color from plant pigments in the hen’s food and are made primarily of fats, proteins, and essential nutrients. On the other hand, the colorless liquid present in the egg is called egg albumin, It forms around the yolk later and provides cushioning to the embryo and the protective shell.
3. What is the difference between lyophilic sols and lyophobic sols?
In Lyophilic sols, there is a strong attraction between the dispersed phase and the dispersion medium. i.e., the dispersed phase has a great affinity for the dispersion medium and is reversible. If water is used as the dispersion medium then lyophilic sols are called hydrophilic sols. Eg: Starch, gum, gelatin, starch, proteins, rubber, egg albumin, etc.
In lyophobic sols, there is very little or no interaction between the dispersed phase and the dispersion medium i.e, a dispersed phase has no affinity towards the dispersion medium and is irreversible. If water is used as the dispersion medium, then lyophobic sols are called hydrophobic sols. Eg: metal hydroxides and metal sulfides, etc.
4. Write some methods of purification of colloids.
The colloidal solutions obtained from various preparation methods are not pure. The impurities present in colloids are suspended particles and electrolytes. The presence of electrolytes in a smaller concentration stabilizes a sol but their presence in a higher concentration destabilizes it. So it is necessary to purify the colloidal solution by removing the electrolyte impurities present in them. Some methods used commonly for the purification of colloids are: