Química Simples #18 - [Prop. Coligativas] - Ebulioscopia (Ponto de Ebulição)

Summary

In this video, the concept of boiling point, or ebullioscopy, is explained in detail. The boiling point is the temperature at which a liquid transitions into a gas, linked to vapor pressure. As the temperature increases, the vapor pressure rises, leading to the formation of bubbles in the liquid. The video also covers how adding a solute to a solvent raises the boiling point, with the interaction between the solute and solvent making it harder for the solvent to vaporize. This results in a higher boiling point in solutions compared to pure substances. The lesson ends with an example of seawater, which boils at a higher temperature due to the dissolved salt.

Takeaways

• 😀 The boiling point (also called ebullioscopy) is the temperature at which a liquid changes completely from the liquid state to the gaseous state.
• 😀 The boiling point is related to vapor pressure, which increases when the temperature of the liquid rises.
• 😀 As a liquid is heated, its vapor pressure increases, and at a certain point, bubbles of vapor form at the bottom of the liquid.
• 😀 The vapor pressure inside the bubbles doesn't initially rise due to atmospheric pressure, but as the liquid heats, the vapor pressure overcomes the atmospheric pressure, allowing boiling to occur.
• 😀 At sea level, the boiling point of water is 100°C at 1 atmosphere of pressure, but as altitude increases, atmospheric pressure decreases, lowering the boiling point.
• 😀 When a solute is added to a solvent, it increases the boiling point of the solution compared to the pure solvent.
• 😀 The more solute added to a solution, the higher the boiling point due to stronger interactions between the solute and solvent molecules.
• 😀 The concept of ebullioscopy refers to the phenomenon where solutions have a higher boiling point than pure substances.
• 😀 Seawater has a higher boiling point than pure water due to the dissolved salt, which increases the difficulty in forming vapor bubbles.
• 😀 The addition of solute to a solvent creates a higher boiling point because it interferes with the solvent’s ability to vaporize, making it harder to form vapor bubbles.

Q & A

What is the boiling point, also known as ebullioscopy?

The boiling point, or ebullioscopy, is the temperature at which a liquid completely changes from its liquid state to its gaseous state.

How is the boiling point related to vapor pressure?

The boiling point is related to vapor pressure because as the temperature increases, the vapor pressure also increases. Once the vapor pressure equals the atmospheric pressure, boiling occurs.

What happens when you heat a liquid, like water, in a container?

When you heat a liquid, its vapor pressure increases, and at a certain point, the vapor pressure becomes strong enough to form bubbles of vapor within the liquid. This is when boiling begins.

What are the little bubbles that appear in a pan when boiling water?

The little bubbles are water molecules that have transitioned from the liquid state to the vapor state. These bubbles form at the bottom of the container and rise as the liquid boils.

Why don't the bubbles rise initially when boiling a liquid?

At the beginning, the bubbles don't rise because the vapor pressure inside them is not strong enough to overcome the atmospheric pressure, so the bubbles stay at the bottom of the container.

How does atmospheric pressure affect the boiling point of water?

At sea level, the boiling point of water is 100°C because the atmospheric pressure is 1 atmosphere. However, as you go higher in altitude, atmospheric pressure decreases, and so does the boiling point.

What is the effect of adding a solute to a solvent on the boiling point?

When a solute is added to a solvent, the boiling point of the solution increases. This happens because the solute particles interfere with the solvent molecules, making it more difficult for the solvent to evaporate and form vapor bubbles.

Why does a solution have a higher boiling point compared to a pure solvent?

A solution has a higher boiling point because the presence of solute particles reduces the solvent's ability to evaporate, requiring more energy (higher temperature) to reach the boiling point.

What is the relationship between the amount of solute in a solution and the boiling point?

The more solute present in a solution, the higher the boiling point. This is due to the increased interaction between solute and solvent, which makes it harder for the solvent to boil.

Can you give an example of a liquid with a higher boiling point due to dissolved substances?

Seawater is an example of a liquid with a higher boiling point than pure water. This is because it contains dissolved salts, which raise the boiling point of the water.