Dispersi Koloid dan Sifat-sifatnya

Summary

This video script focuses on a practical session of physical pharmacy, specifically about colloidal dispersion and its properties. The objectives include understanding colloid definitions, classifications, and their characteristics. The session explores the Tyndall effect, the preparation of colloidal solutions (gelatin, FeCl3, and sodium lauryl sulfate), and tests such as reversibility, viscosity, and the effects of electrolytes. The script also discusses the interaction between colloidal particles and other substances, demonstrating how their properties change with different treatments, such as adding alcohol or NaCl. The key takeaway is that concentration and external factors influence the stability and behavior of colloidal systems.

Takeaways

• 😀 The main topic of the practical session is the study of colloid dispersion and its properties.
• 😀 The goal of the session is for students to understand the definition of colloids, their classification, and their properties.
• 😀 Colloid dispersion involves three systems: molecular (monomolecular), colloid, and coarse dispersion (e.g., suspension).
• 😀 Colloids are classified into three types: lyophilic (e.g., gelatin), lyophobic (e.g., FeCl3), and amphiphilic (e.g., sodium lauryl sulfate).
• 😀 The materials used in the experiment include FeCl3, sodium lauryl sulfate (SLS), and gelatin in varying concentrations.
• 😀 The preparation of colloidal solutions involves dissolving the materials in appropriate solvents, such as hot water or distilled water.
• 😀 The Tyndall effect is demonstrated by shining light through colloidal solutions, showing light scattering in colloidal substances.
• 😀 A reversible colloid system is demonstrated with gelatin and SLS, while FeCl3 shows irreversible behavior due to its lyophobic nature.
• 😀 The viscosity of the colloidal solutions is tested using a viscometer, with the results showing that higher concentrations lead to higher viscosity.
• 😀 Electrolyte effects on colloid stability are tested by adding NaCl to colloidal solutions, demonstrating the effect of added electrolytes on colloidal dispersions.
• 😀 Alcohol addition to colloidal solutions (like gelatin) is tested to observe the formation of precipitates, indicating the relationship between concentration and precipitation.

Q & A

What is the primary objective of the practical session described in the script?

The primary objective is for students to understand the definition, classification, and properties of colloids, including the phenomenon of Tyndall effect.

What are the three types of dispersion systems mentioned in the script?

The three types of dispersion systems are molecular (monomolecular), colloidal, and coarse dispersion.

What are the three types of colloids mentioned, and what are their examples?

The three types of colloids are: 1) Lyophilic colloids (e.g., gelatin), 2) Lyophobic colloids (e.g., FeCl3), and 3) Amphiphilic colloids (e.g., sodium lauryl sulfate).

What tools and materials were used in the experiment?

The tools and materials include a 100 ml beaker, a 10 ml pipette, a porcelain dish, a stopwatch, a stir bar, a 100 ml volumetric flask, and various colloidal substances like FeCl3 and gelatin.

How is colloidal solution prepared in this experiment?

To prepare colloidal solutions, the required colloidal substances (e.g., FeCl3, sodium lauryl sulfate, gelatin) are dissolved in suitable solvents like hot water or distilled water.

What is the Tyndall effect, and how is it demonstrated in the experiment?

The Tyndall effect is the scattering of light by colloidal particles. In the experiment, the scattered light from various colloidal solutions (like sodium lauryl sulfate and gelatin) confirms this effect.

What does the experiment reveal about reversible and irreversible colloids?

The experiment demonstrates that some colloids, like gelatin and sodium lauryl sulfate, are reversible (they return to their original form after cooling), while others like FeCl3 are irreversible.

How does the viscosity of colloidal solutions vary with concentration?

The viscosity of colloidal solutions increases with higher concentrations, as seen in the different times required for solutions with varying concentrations of gelatin.

What is the effect of adding electrolytes (e.g., NaCl) to colloidal solutions?

Adding electrolytes like NaCl to colloidal solutions can lead to the formation of precipitates, making the colloidal solution more stable by reducing the particles' repulsion.

What does the experiment show about the effect of alcohol on colloidal solutions?

The experiment shows that when alcohol (e.g., 96% ethanol) is added to colloidal solutions like gelatin, it causes the colloidal particles to aggregate and form a precipitate, with the extent depending on the concentration of the colloid.