To Prepare a Colloidal Solution (or Sol) of Egg Albumin

Albuminoids are albumin-containing substances. They are proteins and very necessary for the human body. Albumin in eggs is a rich source of proteins. It is required for the growth and development of an organism. Egg albumin in water forms a lyophilic colloidal solution. Colloidal solutions are heterogeneous systems and contain a solute and solvent. Depending upon the affinity of the dispersed phase with the dispersion medium, there are two types of colloidal solutions- lyophilic- solvent loving and lyophobic- solvent repelling. Egg albumin forms a lyophilic sol with cold water. There are various colloidal solutions, such as sols, emulsions, foam, and aerosols. Other lyophilic sols are starch sol, gum sol, rubber sol, etc.

Table of Contents

• Aim 

• Results

Aim 

To prepare a colloidal solution (or sol) of egg

Apparatus required

• Beakers

• Measuring cylinder

• Pipette

• 5% NaCl solution

• Distilled water

• Eggs

• Glass rod

Theory

Eggs are made up of egg yolk and egg white. Egg albumin is a part of the egg white and is highly proteinaceous. This egg albumin forms a lyophilic sol with water. The albumin remains suspended in the dispersion medium without the process of heating. This colloidal solution is very stable and does not get affected by the presence of impurities or electrolytes. Sols' stability depends on the charge on its surface and its solubility in the dispersion medium. Lyophilic sols are stable as they are highly soluble in their solvents.

Procedure

1. Take an egg, break it open, and separate the egg yolk and egg white. 

2. The egg white contains albumin, hence take the egg white and pour it inside a beaker.

3. Prepare 100ml of  5%(w/v) solution of NaCl in distilled water and place it inside a beaker.

4. Take the egg albumin and pour it slowly into the beaker containing the NaCl solution. 

5. Keep constantly stirring while pouring the albumin into the saltwater solution.

6. After all the solution is poured and mixed well, filter out the contents in the beaker using filter paper.

7. This is the final-prepared egg albumin sol in water.

Observations

Egg albumin forms a___________colored lyophilic colloidal solution. This colloidal solution contains water as a dispersion medium, and albumin particles are in the dispersed phase.

Result

The colourless liquid of the egg is known as the egg white and contains an important protein known as albumin. It is a lyophilic sol because it shows high affinity with the solvent medium. It is a very stable solution at room temperature.

Precautions

1. Be very careful while breaking the egg.

2. Make the NaCl solution with the correct concentration.

3. Where lab coats and other safety gear throughout the experiment.

4. Clean the glassware and all the requirements before and after use.

Lab Manual Questions

1. How to recognise egg yolk and egg albumin?

Ans: Egg yolk is a yellow substance that appears circular. Surrounding the yolk is a colourless liquid known as egg albumin or egg white, containing the protein albumin.

2. What types of albumins are present in an egg white?

Ans: The egg white contains these types of albumins majorly-

• Ovalbumin- It is the primary protein of egg white. It makes up 54% of the protein in the egg white.

• Ovotransferrin- It is a type of glycoprotein which makes about 12% of the protein in the egg white.

3. What are egg yolk and egg white?

Ans: The yellow part of the egg is the egg yolk, which is the centre of the egg and contains vital nutrients for the body. It contains various vitamins. Egg white is a colourless colloidal solution which contains 90% water and 10% of various proteins such as albumin, globulin etc.

4. How will you prepare 100ml of 5%(\[\dfrac{w}{v}\]) of NaCl solution?

Ans: To prepare 5%(\[\dfrac{w}{v}\]) of NaCl solution-

• Weigh 5 grams of NaCl on a weighing balance. Take 100 ml of distilled water in a measuring cylinder.

• Add 5 gm of NaCl into a 250 ml beaker. Add 30 ml of distilled water and dissolve the NaCl. Slowly add the remaining 70 ml of Distilled water. Keep on stirring while adding water.

• 5%(\[\dfrac{w}{v}\]) of NaCl solution is prepared.

Viva Questions

1. What are colloidal solutions?

Ans: Colloidal solutions are heterogeneous mixtures of solute and solvent, and they do not mix completely with each other. Hence the solution contains dispersed particles.

2. How many types of aerosols are present?

Ans: There are two types of aerosols: - Solid aerosols-solid particles in a gas. Liquid aerosols-liquid particles in a gas.

3. What is an alternative name for egg white?

Ans: Egg white is also called albumen, which means ‘white’ in Latin.

4. What is the function of ovalbumin in eggs?

Ans: Ovalbumin provides nutrition to the growing embryo in the egg, and it also contains digestive enzymes.

5. What are other minerals present in egg albumen?

Ans: Egg albumen contains other nutrients and minerals such as Sodium, Potassium, Vitamins K, vitamin A, Calcium, Copper etc.

6. What is a saline solution?

Ans: A mixture of salt and water is known as a saline solution. A normal saline solution contains 0.9% sodium chloride, similar to sodium concentration in blood and tears. 

7. How do coagulants work?

Ans: Coagulants generally contain positive charges over their surfaces, and solute particles in colloidal sols generally have negative charges. The charges of coagulants and solute particles of sol neutralise with each other and, as a result, form lumps and settle down out of the colloidal solution.

8. What is the function of anticoagulants?

Ans: Anticoagulants do not allow the particles of a colloidal solution to settle down.

9. How can you determine whether the given solution is colloidal or true?

Ans: A true solution will not scatter or reflect the light, but the light will easily pass through the true solution. In a colloidal solution, the light will be scattered by the dispersed particles so that the light will be readily visible. 

10. Give some examples of colloidal solutions seen every day.

Ans: Milk, Fog, Jelly, Starch solution, egg albumin, Smoke, Whipped cream, Butter, cheese, etc. are all examples of colloidal solutions seen in day-to-day life.

Practical Based Questions (MCQs)

1. A colloidal solution wherein solid/liquid particles are dispersed in gas is known as_________

1. Foam

2. Solution

3. Solvent

4. Aerosol

Ans: Aerosol

2. 10% NaCl solution is called as________________

1. An aqueous solution of salt

2. Brine solution

3. Salty solution

4. Colloidal solution

Ans: Brine

3. Which of the following is a heat-labile protein of egg white

1. Ovalbumin

2. Albumin

3. Ovotransferrin

4. Mucoproteins

Ans: Ovotransferrin

4. Human contains___________amount of albumin

1. 10% - 15%

2. 30% - 40%

3. 4% - 5%

4. 0% - 2%

Ans: 4% - 5%

5. The outer white coating of the egg is made of __________

1. Calcium hydroxide

2. Calcium carbonate

3. Sodium hydroxide

4. Sodium chloride

Ans: Calcium carbonate

6. KCl in water:___________, Colloidal solution:__________

1. The true solution, Sols

2. The colloidal solution, emulsions

3. The true solution, Salt solutions

4. Both B and C

Ans: True solution, Sols

7. When two immiscible liquids are mixed, they form

1. Colloid sols

2. True solutions

3. Emulsions

4. Foams

Ans: Emulsions

8. Fog is made up of_________dispersed in_________

1. Solid, gas

2. Liquid, gas

3. Gas, liquid

4. Gas, solid

Ans: Liquid, gas

9. Scattering of light by the colloidal solution is known as__________

1. Magnetic effect

2. Refraction of light

3. Transmission of light

4. Tyndall effect

Ans: Tyndall effect

10. To prepare a colloidal solution of egg albumin, which of the following is not required?

1. NaCl

2. Distilled water

3. Egg white

4. Egg yolk

Ans: Egg yolk

Conclusion

From the above experiment, we can conclude that albumin is a protein component of egg white. Albumin is a colloid which is a lyophilic sol and is very stable. Albumin in the egg is highly nutritious and is a colourless liquid. A sodium chloride solution is required to prepare a colloidal solution of albumin. It is a sol type of colloidal solution, as the dispersed phase here is solid, and the dispersion medium is liquid.