02 Solutions colloids etc

Summary

In this video, the concepts of electrolytes, suspensions, colloids, and hygroscopic compounds are explored in detail. Electrolytes, such as salt and hydrochloric acid, conduct electricity when dissolved in water, while substances like sugar do not. The video also covers suspensions, where particles settle out over time, and colloids, which remain stable. Emulsions, like mayonnaise, are discussed as mixtures of two immiscible liquids stabilized by an agent. Additionally, the Tyndall effect demonstrates how light is scattered by colloidal particles. Hygroscopic compounds, like silica gel, absorb moisture from the air, serving as desiccants in various products.

Takeaways

• 😀 Electrolytes are compounds that conduct electrical current when dissolved in a solution, requiring dissolved ions to carry the charge.
• 😀 Pure water does not conduct electricity on its own; it only conducts well when dissolved ions, like salt, are present.
• 😀 Strong electrolytes, like salt (sodium chloride) and hydrochloric acid, completely dissociate in water and conduct electricity well.
• 😀 Non-electrolytes, such as sugar, do not dissociate into ions and do not conduct electricity when dissolved in water.
• 😀 Weak electrolytes, like acetic acid (vinegar), partially dissociate in water, allowing some electrical conductivity but less than strong electrolytes.
• 😀 A suspension is a heterogeneous mixture where larger particles settle out over time (e.g., muddy water).
• 😀 Colloids, such as Elmer's glue or shampoo, contain smaller particles than suspensions and do not settle out over time.
• 😀 An emulsion is a colloidal mixture of two liquids that usually do not mix, like oil and vinegar, when an emulsifying agent, like egg yolk in mayonnaise, is added.
• 😀 The Tyndall effect occurs when light is scattered by particles in a colloid, allowing you to see the light beam passing through, unlike in a solution.
• 😀 Hygroscopic compounds, such as desiccants, absorb moisture from the air, and when they absorb too much, they can dissolve and form a solution.

Q & A

What is an electrolyte?

An electrolyte is a compound that conducts electrical current when dissolved in a solution. The dissolved ions in the solution allow it to conduct electricity.

Why does pure water not conduct electricity?

Pure water does not conduct electricity because it lacks dissolved ions. For water to conduct electricity, substances like salt need to dissolve and release ions into the water.

What is the difference between a strong electrolyte and a weak electrolyte?

A strong electrolyte completely dissociates into ions in solution, allowing for high conductivity (e.g., salt, hydrochloric acid). A weak electrolyte only partially dissociates, leading to weaker conductivity (e.g., acetic acid).

Why is sugar not an electrolyte?

Sugar is not an electrolyte because, when dissolved in water, it does not dissociate into ions. For a substance to be an electrolyte, it must release ions that can carry an electrical charge.

What is a suspension and how does it differ from a solution?

A suspension is a heterogeneous mixture where large particles are suspended in a liquid and will eventually settle over time, like muddy water. In contrast, a solution is a homogeneous mixture where the solute is completely dissolved in the solvent, and the particles do not settle.

What is the Tyndall Effect, and how can it be used to distinguish colloids from solutions?

The Tyndall Effect is the scattering of light by colloidal particles, which makes the light beam visible. This effect occurs in colloids because their particles are large enough to scatter light, unlike in solutions where the particles are too small.

What are colloids, and how do they differ from suspensions?

Colloids are mixtures where the particles are smaller than in suspensions but larger than in solutions. These particles do not settle out over time. In contrast, suspension particles are large and will eventually settle out.

What is an emulsion, and how is it different from a simple mixture?

An emulsion is a colloid formed when two liquids that do not mix (like oil and vinegar) are combined with the help of an emulsifying agent (e.g., egg yolk in mayonnaise). Unlike simple mixtures, emulsions remain stable and do not separate over time.

What is the role of the emulsifying agent in an emulsion?

An emulsifying agent, such as egg yolk, helps two liquids that normally do not mix (like oil and vinegar) to combine and stay mixed. It stabilizes the emulsion by preventing the liquids from separating.

What are hygroscopic compounds, and how do they work?

Hygroscopic compounds are substances that absorb moisture from the air. They are often used as desiccants in products to keep them dry, like the silica gel packets in shoes or electronics.