To prepare a colloidal solution of starch in water and egg albumin/milk in water - Lab Work

To prepare a colloidal solution of starch in water and egg albumin/milk in water and distinguish between these on the basis of:

(i) transparency
(ii) filtration criterion

(iii) stability

In colloidal solution,  the size of particles are smaller than 10^-5 cm or smaller. It is heterogeneous in nature and particles of one substance dispersed through another substance. It has dispersed medium and dispersed phase.

Beakers, Test tubes, Egg albumin/milk, Glass Rod, Water

Step 1:

Step 2: 10g of fine soil (without litter), fine chalk powder and fine sand is added in each beaker separately.

Step 3: Solution is stirred with the help of glass rod.
Step: Put the solutions in test tubes and labelled them as A, B and C.

Property	Experimental Procedure	Observation	Inference
Transparency	Small strip of cellophane paper is pasted on each test tubes and the coloured paper of each test tube is observed from other side of test tube.	Coloured spot appears dim from the other side of test tubes A and B.	A colloid is translucent.
Filtrate	Contents of test tubes labelled as A, B and C are filtrated.	Filtrate obtained is translucent. No residue left on the filter paper in both the cases.	Components causing colloid cannot be separated by filtration.
Stability	Leave the test tubes without disturbance for 20-25 minutes.	No change is observed in test tubes A and B.	Colloids are stable and solute particles do not settle down when left undisturbed.

Results and Discussion
Colloidal solutions are translucent and their particles can pass through filter paper to give translucent filtrate. No residue particles are left as residue on the filter paper.

Precautions
(i) Handle the materials and solutions with care.
(ii) While filtering a solution drop the contents along a glass rod into the beaker.
(iii) Keep the sample undisturbed while checking stability.

Go to List of Experiments