Dispersões: Soluções, Suspensões e Coloides |O MELHOR RESUMO|

Summary

This video explains the differences between solutions, suspensions, and colloids, which are all types of dispersions. It defines dispersion and introduces key terms such as 'dispersant' and 'dispersed' based on the relative quantities of substances. The video compares the characteristics of each type of mixture, emphasizing the size of particles and their behavior under gravity or filtration. It covers solutions (homogeneous, with particles smaller than 1 nanometer), suspensions (heterogeneous, with particles larger than 1000 nanometers), and colloids (heterogeneous, with particles between 1 and 1000 nanometers, displaying the Tyndall effect). Examples of each type are provided, with practical applications highlighted.

Takeaways

• 😀 Dispersion refers to the process of mixing substances, where one substance distributes itself within another in the form of small particles.
• 😀 A dispersion consists of two components: the dispersant (the substance allowing distribution) and the dispersed (the substance being distributed).
• 😀 Solutions are homogeneous mixtures where particles are extremely small (less than 1 nanometer) and do not settle or separate under gravity.
• 😀 In solutions, the dispersant is typically the substance present in a larger quantity, while the dispersed is present in a smaller amount.
• 😀 Suspensions are heterogeneous mixtures with larger particles (greater than 1000 nanometers) that can settle or be separated using filters.
• 😀 The key difference between solutions and suspensions lies in the size of the dispersed particles; suspensions have larger particles than solutions.
• 😀 Colloids are also heterogeneous mixtures, with particles between 1 and 1000 nanometers in size. They are intermediate between solutions and suspensions.
• 😀 Colloids do not settle like suspensions and can only be separated with specialized equipment, such as ultracentrifuges and ultrafilters.
• 😀 The Tyndall effect is a phenomenon where light is scattered when passing through colloidal mixtures, which helps to identify colloids.
• 😀 Common examples of colloids include milk, blood, fog, and gels like gelatin, and these can vary based on the physical state of the components.

Q & A

What is the general concept of dispersion as discussed in the video?

Dispersion refers to mixing different substances, where one substance is distributed in the other in the form of small particles. The substance that is distributed is called the 'dispersed', and the one allowing the distribution is called the 'dispersing agent' or 'dispersant'.

How do you determine the dispersant and dispersed in a mixture like water and alcohol?

The dispersant is the substance that is present in a greater quantity by mass. For example, in a 50ml mixture of water and alcohol, water is the dispersant because it has a higher mass due to its density compared to alcohol.

What are the key characteristics of solutions?

Solutions are homogeneous mixtures where the dispersed particles are very small, such as atoms, ions, or small molecules. These particles do not sediment under gravity, cannot be separated by ordinary filters, and are invisible even under an electron microscope.

What distinguishes suspensions from solutions?

Suspensions are heterogeneous mixtures where the dispersed particles are larger than in solutions. These particles can sediment under gravity and are larger than 1,000 nanometers, making them visible to the naked eye or through a regular microscope.

Can suspensions be filtered easily?

Yes, suspensions can be separated using a regular filter, unlike solutions. The larger particle size allows them to be physically filtered out.

What is the typical particle size range for colloids?

Colloids have particle sizes ranging between 1 and 1,000 nanometers. These particles are too small to settle under gravity but are large enough to scatter light, making them visible through an electron microscope.

What is the Tyndall effect, and how does it apply to colloidal dispersions?

The Tyndall effect is the scattering of light when it passes through a colloidal dispersion. This phenomenon makes the particles in a colloid visible under certain conditions, such as when light beams pass through a colloidal mixture like dust in the air or fog.

What are some examples of colloidal dispersions mentioned in the video?

Examples of colloidal dispersions include milk, blood, juice, smoke, fog, whipped cream, and gelatin.

How can the state of the dispersed and dispersing phases classify colloids?

Colloids can be classified based on the physical state of the dispersed and dispersing phases, such as aerosols (e.g., smoke, fog), emulsions (e.g., ice cream, mayonnaise), foams (e.g., whipped cream, marshmallows), sols (e.g., plasma), and gels (e.g., gelatin).

What is the relationship between colloidal dispersions and light in real-world examples?

In real-world situations, colloidal dispersions like fog or dust in the air can scatter light. This is why headlights on vehicles are required to be dimmed during foggy conditions, as the scattered light can reduce visibility and cause accidents.