Biochem Lab Rep 2

Name: Revina J. Borgoños

Section: Pharmacy 2B

Instructor: Jonah Micah J. Madera

Date Performed: July 8, 2019 Date Submitted: July 15, 2019

Experiment 2 Colloids

I. OBJECTIVES: 1. Prepare the two types of colloidal systems. 2. Differentiate between emulsoid and suspensoid in terms of properties and reactions.

II.

PROCEDURE: A. Preparation of Emulsoid 

10 grams of gelatin was dissolved in a beaker containing a 200 ml of hot water with a constantly stirring.



1 ml of the prepared emulsoid was poured in a test tube and cooled down under a tap water.



The test tube containing emulsoid was brought and heated again using a water bath.



It was then observed.

B. Preparation of Suspensoid 

In a beaker, with a 200ml of boiling water, 1ml of a saturated ferric chloride solution was added. The result was then observed.



We repeated the last two procedures in Part A and compared the obtained results.

C. Foam Formation 

A 10 ml 0f 5% gelatin solution was placed in a test tube and shaken.



Noted the result after 15 minutes if it formed a permanent foam.



A 10 ml of colloidal ferric chloride solution (suspensoid) vigorously with air was placed in a test tube then shaken and noted the result after 15 minutes.

D. Precipitation with Electrolytes 

Placed 5 ml of 5% gelatin solution in a test tube.



Saturated Ammonium Sulfate was added dropped by dropped and noted the number of drops, until permanent precipitate was formed.



The procedure was repeated using colloidal ferric chloride instead of 5% gelatin solution.

E. Reversibility 

In a 5ml of colloidal ferric chloride, 1ml of 10% MgSO4 solution was added in a test tube and we let it stand for 30 minutes.



The first procedure was repeated but using 5% gelatin solution instead of colloidal ferric chloride.



Solid MgSO4 was then added when there is no precipitate formed in gelatin solution until it became saturated.



The supernatant fluids was decanted from each of the two colloids.



Excess water was then added and was noted if the two colloids were reversible or not.

F. Precipitation of suspensoid particle with monovalent and bivalent ions which carry charges of the opposite signs 

A 5ml of 1% colloidal ferric chloride was placed in a test tube.



0.45N NaCl solution was then added dropped at a time (noted the number of drops) then shaken it every addition of drops until a permanent precipitation is formed.



Procedure 1 is repeated but, using 1N solution of Na2SO4 and 1N MgCl2 instead of 1% colloidal ferric chloride.



The result was then compared.

G. Protective Action of Emulsoids 

A 5ml of 0.05N AgNO3 was placed in a test tube and was added with 5 drops of concentrated nitric acid.



5ml of 0.45N NaCl was then added in a solution and noted the copious precipitate.



Repeated the experiment but added 1ml of 5% gelatin solution for each 0.05N AgNO3 and 0.45N NaCl before mixing.

III.

RESULTS and INTERPRETATION Procedure

Observations Upon mixing a gold colored solution was produced.

A. Preparation of an emulsoid When cooled:  It has gelatinized (formed in to solid state) When heated:  It returned into liquid state

Interpetation: In this procedure 5% gelatin solution is used as an emulsoid. Emulsoid is a colloidal dispersion in which the dispersed particles are more or less liquid and exert a certain attraction on and absorb a certain quantity of the fluid in which they are suspended. It also has a lyophilic characteristics in which enable to take up large amount of water which is seen as a gelatin form. Because of the stability of an emulsoid and has a strong forces of attraction it produced a gelatinized emulsoids when added tow water. However when heated, the mixture of gelatin and water liquefies again by breaking the bonds of a water and a colloid. Also, due to the elevation of temperature as it was reheated causes the emulsoid to liquefy as its original form.

Procedure B. Preparation of Suspensoid

Observations Formed reddish semi-solid chunks and settled in the bottom of the beaker. When cooled: Did not dissolve in water When heated: It dissolved in water and turned into a clear solution

Interpretation: Hydrolysis is a chemical process whereby a compound is cleaved into two or more simpler compounds with the uptake of the H and OH parts of water molecule, this said we have decided to use this technique in preparing the suspensoid in which the ferric chloride was reduce to ferric hydroxide [ FeCl3 + 3H2O  Fe(OH)3 + 3HCl].

A lyophobic solution which is suspensoids has a lack of preference for the solvent that’s why saturated ferric chloride failed to dissolve in the water because of having a slight affinity for the dispersion medium. Iron is an example of an inorganic substances which are mostly lyophobic which has a less stable and has a weak forces of attraction causing the colloids to not easily mixed with the solvents.

Procedure C. Foam Formation

Observation Gelatin- Emulsoid: Formed a permanent foam after 15 minutes. FeCl3- Suspensoid: Do not formed a permanent foam.

Interpretation: A suspensoid as a lyophobic properties and has only a viscosity range as the same to the dispersion phase that’s why it is not capable of forming permanent foam while, in terms of emulsoid, the emulsoid has lyophilic properties and has a higher or greater viscosity than the dispersion medium hence forming permanent foams. Emulsoids cannot easily return to its liquid state thus the formation of foam retained.

Procedure

Observation

D. Precipitation with Electrolytes

Number of drops of ammonium sulfate added to form a permanent precipitate

Gelatin- Emulsoid: Precipitate at 5 drops FeCl3- Suspensoid: Precipitate at 37 drops. Appearance of Precipitate

Gelatin- Emulsoid: Dark-brown precipitate FeCl3- Suspensoid: No precipitate

Interpretation: Emulsoid necessitate a large amount of electrolytes to form a precipitate only at high concentration but, on the other hand, suspensoid does not form a precipitate for the reason that they carry same charges with the solvent. It was precipitated by ions carrying charges of opposite signs.

Procedure E. Reversibility Precipitate after adding 1ml of10%

Observation Gelatin (emulsoid)

FeCl3 (Suspensoid)

No precipitate

No precipitate

Slightly liquefied

No changes

Crystal Residue

Completely Dissolved

MgSO4 After 15 minutes then addition of solid MgSO4 After decantation and addition of excess water

Interpretation: After decanting the dispersion plate which contains water, the residue which is a crystal was reconverted into colloidal state when water was added again. This explains the reversibility of an emulsoid. The stability of an emulsoids enables it to revers. In suspensoid, the forces are too weak making them less stable and the residue is not convertible even after adding water, it still remains irreversible.

Procedure

1 % Colloidal Ferric Chloride

F. Precipitation

# of drops

Observation

particle 0.45 N NaCl

1-15

monovalent 1 N Na2SO4

1-15

1st drop caused turbidity- 15th drop caused even turbidity 1st drop caused turbidity- 15th drop caused even turbidity 1st drop caused turbidity- 15th drop caused even turbidity

suspensoid with and

of

bivalent

ions

1-15

1 N MgCl2

which carry charges of the opposite signs

Interpretation:

Procedure

Observation

G. Protective

5 drops of concentrated

Action of Emulsoids

5 ml of 0.45 N NaCl

nitric acid 5 ml of 0.05 N

1 drop = turbidity

Copious precipitate

No precipitate

No reaction

AgNo3 1ml of 5% gelatin to

NaCl

AgNO3

and

Interpretation: The particles of protective colloids is believed to be absorbed by lyophobic colloidal particles and thus forms a covering over the surface of lyophobic colloidal particles. The lyophobic colloid thus behaves as lyophilic colloid and is precipitated less easily by electrolytes.

IV.

DOCUMENTATION

A.

PREPARATION OF EMULSOID

B.

PREPARATION OF SUSPENSOID

C.

FOAM FORMATION

D.

PRECIPITATION WITH ELECTROLYTES

E.

REVERSIBILITY

F.

PRECIPITATION OF SUSPENSOID PARTICLE WITH MONOVALENT AND BIVALENT IONS WHICH CARRY CHARGES OF THE OPPOSITE SIGNS

G.

PROTECTIVE ACTION OF EMULSOIDS

V.

CONCLUSION In conclusion, the experiment just shows that even if they are the same colloids, emulsoid

and suspensoid still varies in each perspective characteristics. For in fact, they seem almost the polar opposite of each other. Emulsoid is a lyophilic where it has affinity for the solvent, the water. During the experiment, the prepared emulsoids was gelatinized due to the greater stability between two molecules that enables them to interact or having the attraction with the solvent. But when the temperature increases, it causes the gelatinized emulsoids to liquefy because the bonds between the molecules was break due to higher temperature. While, a suspensoid is lyophobic, which means that it has no affinity for the solvent making it less stable and cannot interact directly between the colloidal particles and solvent particles which is water. This main characteristic is what droves them apart. In terms of having greater affinity to water, in forming permanent foam and forming a precipitate emulsoid seems to have an advantage due to its inert character. It has a higher viscosity than its dispersion medium compared to suspensoids. Emulsoids also can precipitate at only with a high concentration. Thus, suspensoids does not form a permanent foam due to fact that it has a same number of viscosity with its solvent. However, suspensoid showed that it can precipitate with lower concentration of electrolytes. Lastly, Emulsoids are said to be reversible mainly due to its stability while suspensoids are not stable making the particles irreversible. This experiment had shown exemplary opposite colloids and how they are differentiated.