Page 116 - Biology - XII

Observations
Precipitation of emulsoids with electrolytes

S. No. Emulsoid Electrolysis (NH ) SO Alcohol Inference
4 2 4
1. Protein-in-water (Wheat fl our)

2. Starch-in-water (Rice fl our)
3. Protein-in-water (Gram fl our)

(Precipitate may or may not be formed, this is to be studied/observed. Note your observations.)

Conclusion
1. Emulsion of protein-in-water salts with electrolysis.
2. Emulsion of starch-in-water _______________ with alcohols/electrolysis.

Precautions
1. Large quantity of electrolyte is needed for ‘salting out of emulsion’.

VIVA VOCE

Q1. What is ‘salting out’ of emulsion?
Ans. The precipitation of dispersed particles of emulsion in presence of charges is salting out.
Q2. Why did you use wheat fl our in this experiment?
Ans. Wheat has protein. To make an emulsion of protein-in-water, wheat fl our was used.
Q3. What are starch emulsions?
Ans. The emulsions prepared by using starch-in-water are called starch emulsions.

Q4. What is emulsion?
Ans. A suspension of particles in liquid or two immiscible liquids when shaken together make emulsion.
Q5. Give an example of emulsion.
Ans. Oil in water and water in oil.

COMPETENCY BASED QUESTIONS

Multiple Choice Questions

Q1. There are diff erent types of colloidal systems. Their number is

(a) 3 (b) 5 (c) 6 (d) 10
Q2. The zig-zag movement of dispersed particles in a suspension is called
(a) osmosis (b) diff usion
(c) tyndall eff ect (d) brownian movement

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