Preparation of Lyophilic and Lyophobic Sols – MeitY OLabs


Preparation of Lyophilic and Lyophobic Sols Preparation of colloidal solution of starch We require, an electronic balance, starch
powder, butter paper, dropper, spatula, glass rod, pestle and mortar, distilled water, beakers,
wire gauze, tripod stand, Bunsen burner, funnel, filter paper, conical flask, iron stand with
clamp etc. Weigh 1 gram of starch using the electronic
balance. Transfer the weighed quantity of starch into
the mortar and using the dropper add a few drops of distilled water to it.
Grind the starch with the pestle to make it into a thin paste.
Transfer the paste to a 50 milliliters beaker. Take about 100 milliliters of distilled water
in a 250 milliliters beaker and heat the beaker so that the water starts boiling.
Pour the paste slowly into the boiling water with stirring using a glass rod.
Continue boiling for about 10 minutes and then allow the beaker to cool.
Fix a filter paper in a funnel which is fixed to a stand and place a glass rod over the
funnel. Filter the contents of the beaker through
the funnel and collect the filtrate in a conical flask.
Label the filtrate as ‘Starch Sol’. Take the starch sol containing sodium chloride
in a conical flask. Take a funnel and fix a parchment membrane
to the stem of the funnel. Tie the membrane to the stem of the funnel
using the thread. Take starch sol.
Pour the starch sol containing sodium chloride into the funnel until two-thirds of the parchment
bag is full. Dip the parchment bag into distilled water
taken in a beaker and fix the funnel in position by means of the clamp.
Allow this to stand for about half an hour. After half an hour, take small amount of water
from the beaker using a dropper. Transfer it into a test tube.
Take small quantity of iodine solution using a dropper.
Add few drops of iodine solution into the test tube containing water. If the colour
does not turn blue, it depicts the absence of starch in water.
Thus it follows that starch molecules do not diffuse through parchment membrane.
Withdraw another 1 milliliter of water from the beaker.
Transfer it into another test tube. Take few drops of silver nitrate solution
using a dropper add it into the test tube containing water.
A white precipitate of silver chloride produced immediately indicates the presence of chloride
ions and hence sodium chloride in water. It follows that sodium and chloride ions diffuse
through the parchment membrane. As sodium ion and chloride ion diffuse out of the starch
sol, it gets free from ions gradually. Replace the water in the beaker with fresh
distilled water. After about 10 minutes, test the presence
of chloride ions. Take a small amount of water from the beaker
using a dropper. Transfer it into a test tube.
Take a few drops of silver nitrate solution using a dropper and add it into the test tube
containing water. If no white precipitate is formed, chloride
ions are absent. This indicates that dialysis is complete,
otherwise the sol still contains chloride ions and therefore the dialysis should be
continued. Preparation of colloidal solution of gum We require, 1 gram gum, dropper, spatula,
glass rod, pestle and mortar, distilled water, beakers, wire gauze, tripod stand, Bunsen
burner, funnel, filter paper, conical flask, iron stand with clamp etc.
Take 1 gram of gum in a mortar. Add few drops of distilled water using a dropper.
Grind the gum using the pestle to make this into a paste.
Transfer the paste into a 50 milliliters beaker using the spatula.
Take 100 milliliters of distilled water in a 250 milliliters beaker and heat the beaker.
(Do not boil the water. Warm water is to be used since gum is quite soluble in warm water).
Pour the paste slowly into the warm water with stirring using a glass rod.
Continue warming for about 10 minutes and then allow the beaker to cool.
Fix a filter paper in a funnel which is fixed to a stand and place a glass rod over the
funnel. Filter the contents of the beaker through
the funnel, using the glass rod, and collect the filtrate in the conical flask.
Label the filtrate as ‘Gum Sol’. Preparation of colloidal solution of egg albumin We require an egg, beakers, glass rod, 5%
sodium chloride solution, filter paper, funnel, conical flask and iron stand with clamp.
Take an egg. Break the outer shell of
the egg by striking it with a glass rod.
Collect the colourless liquid, egg albumin, along with the yellow yolk in a beaker.
Decant the colourless liquid,egg albumin, into another beaker.
Transfer the egg albumin into a beaker containing 5% sodium chloride solution.
Stir it constantly for about 15-20 minutes. Fix a filter paper in a funnel which is fixed
to a stand and place a glass rod over the funnel.
Filter the contents of the beaker through the funnel and collect the filtrate in a conical
flask. Label the filtrate as ‘Egg Albumin Sol’. To prepare a colloidal solution of aluminium
hydroxide We require, 2% solution of aluminium chloride,
silver nitrate solution, dropper, glass rod, distilled water, beakers, wire gauze, tripod
stand, Bunsen burner, funnel, filter paper, conical flask, parchment membrane, iron stand
with clamp etc. Take a 250 milliliters conical flask and clean
it by the steaming-out process. To this cleaned conical flask, add 100 milliliters
of distilled water. Heat the conical flask containing water to
boil by placing the flask over a Bunsen burner. Boil the conical flask containing water by
placing the flask over a Bunsen burner. Take 2% aluminium chloride solution using
a dropper. Add aluminium chloride solution drop wise
to the boiling water. Continue boiling until white gelatinous solution
of aluminium hydroxide is formed. Keep the contents of the conical flask undisturbed
for some time at room temperature. Label the solution as “Aluminium Hydroxide sol”.
Take a funnel. Fix a parchment membrane to the funnel.
Add the Aluminium hydroxide sol into the parchment bag through the funnel until two-thirds of
the bag is full. Fix the funnel with the membrane containing
sol to a stand. Dip the parchment bag into the distilled water
and fix the funnel at that position by means of the clamp.
After half an hour, take small amount of water from the beaker using a dropper.
Transfer it into a test tube. Take few drops of silver nitrate solution
using a dropper. Add few drops of silver nitrate solution into
the test tube containing water. A white precipitate of silver chloride produced
immediately indicates the presence of chloride ions in water.
Replace the water in the beaker with fresh distilled water.
Allow it to stand for 10 minutes. Take a small amount of water from the beaker
using a dropper. Transfer it into a test tube.
Take a few drops of silver nitrate solution using a dropper and add it into the test tube
containing water. If white precipitate is formed, dialysis should
be continued. If no white precipitate is formed, chloride
ions are absent. This indicates that the dialysis is complete, otherwise the sol still contains
chloride ions and therefore the dialysis should be continued. To Prepare a of colloidal solution of ferric
hydroxide We require, 2% solution of ferric chloride,
silver nitrate solution, dropper, glass rod, distilled water, beakers, wire gauze, tripod
stand, Bunsen burner, funnel, filter paper, conical flask, parchment membrane, iron stand
with clamp etc. Take a 250 milliliters conical flask and clean
it by the steaming-out process. To this cleaned conical flask, add 100 milliliters
of distilled water. Heat the conical flask containing water to
boil by placing the flask over a Bunsen burner. Take 2% ferric chloride solution using a dropper.
Add ferric chloride solution drop wise to the boiling water.
Continue boiling until deep red or brown solution of ferric hydroxide is obtained.
Keep the contents of the conical flask undisturbed for sometime at room temperature.
Label the solution as ‘Ferric Hydroxide Sol’. Take a funnel.
Fix a parchment membrane to the stem of the funnel. Using a thread, tie the membrane to
the stem of the funnel. Take ‘Ferric Hydroxide Sol’.
Pour the ferric hydroxide sol into the parchment bag through the funnel till two-thirds of
the bag is full. Fix the funnel with the membrane containing
sol to a stand. Dip the parchment bag into distilled water taken in a beaker and fix
the funnel in position by means of the clamp. Allow it to stand for about half an hour.
After half an hour, take small amount of water from the beaker using a dropper.
Transfer it into a test tube. Take few drops of silver nitrate solution
using a dropper. Add it into the test tube containing water.
A white precipitate of silver chloride produced immediately indicates the presence of chloride
ions in water. Replace the water in the beaker with fresh
distilled water. Allow it to stand for 10 minutes.
Take a small amount of water from the beaker using a dropper.
Transfer it into a test tube. Take a few drops of silver nitrate solution
using a dropper and add it into the test tube containing water.
If white precipitate is formed, dialysis should be continued.
If no white precipitate is formed, chloride ions are absent. This indicates that dialysis
is complete, otherwise the sol still contains chloride ions and therefore the dialysis should
be continued. To prepare colloidal solution of arsenious
sulphide We require, solid arseniuos oxide, hydrogen
sulphide gas, Distilled water, conical flask, beakers, RB flask, glass rod, glass tube,
flutted filter paper, wire gauze, tripod stand, Bunsen burner, kipp’s apparatus, iron stand
with clamp etc. Take a 250 milliliters conical flask.
Clean it by the steaming-out process. Take the cleaned conical flask.
To this cleaned flask, add 0.2 gram of arsenious oxide.
Take 100 milliliters of distilled water in a measuring jar.
Pour it into the conical flask containing arsenious oxide.
Take solution. Boil the solution with stirring for about
10 minutes by placing the flask over the Bunsen burner. Arsenious oxide undergoes hydrolysis
with boiling distilled water to form arsenous acid.
Fix a flutted filter paper in a funnel and place a glass rod over the funnel.
Filter the hot solution in the flask through the flutted filter paper and collect the filtrate
in another beaker. Pass a slow current of hydrogen sulphide gas
into the solution of arsenous acid. Arsenous acid reacts with hydrogen sulphide
to form yellow coloured arsenious sulphide. Continue passing hydrogen sulphide gas till
the intensity of colour does not change further. Expel excess of hydrogen sulphide gas from
the sol by boiling the sol till the escaping gas does not turn lead acetate paper black.
Filter the solution through the fluted filter paper.
Collect the bright yellow filtrate in a dry conical flask and cork it.
Label the filtrate as ‘Arsenious Sulphide Sol’.

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