Solubility | GCSE Chemistry Revision Guide - The Chemistry School

Summary

This video explains the concept of solubility through the example of dissolving sugar in tea. It introduces key terms like solute, solvent, and solution, and discusses factors affecting solubility, such as temperature and pressure. The solubility of solids and gases in solvents is explored, with emphasis on how temperature increases solubility for solids but decreases it for gases. The video also touches on how gases like CO2 are dissolved in carbonated drinks, and how pressure influences the solubility of gases, creating the fizz in drinks like lemonade.

Takeaways

• 😀 Solubility refers to the ability of a solute to dissolve in a solvent, forming a solution.
• 😀 In a cup of tea, sugar dissolves in the tea, but it doesn't disappear; it is still present but no longer visible.
• 😀 The solute is the substance being dissolved (e.g., sugar), while the solvent is the substance doing the dissolving (e.g., tea).
• 😀 A solution is the mixture formed when a solute dissolves in a solvent (e.g., sugar tea solution).
• 😀 Not all substances will dissolve in the same solvent; for example, sand and oil do not dissolve in water.
• 😀 Polar molecules dissolve in polar solvents, while nonpolar molecules dissolve in nonpolar solvents.
• 😀 Solubility is measured as the amount of solute that can dissolve in a specific amount of solvent, typically in grams per 100 milliliters.
• 😀 If a substance cannot dissolve in a solvent, it is considered insoluble for that particular solvent.
• 😀 The solubility of solids generally increases with temperature. For instance, as the temperature of water increases, more salt can dissolve.
• 😀 The solubility of gases in liquids depends on pressure: as pressure increases, more gas can dissolve in the solvent.
• 😀 Gases such as carbon dioxide in carbonated drinks (e.g., lemonade) are dissolved under pressure, and when the pressure is released, the gas escapes, creating bubbles.

Q & A

Why do some substances disappear when dissolved in water while others do not?

The disappearance of substances when dissolved in water is due to the process of dissolution. Some substances, like sugar or salt, dissolve and become part of the solution, making them invisible to the eye, while others, like sand or oil, do not dissolve and remain visible.

What is the term for a substance that dissolves in a solvent?

The substance that dissolves in a solvent is called the 'solute'. In the case of tea and sugar, sugar is the solute.

What is a solution?

A solution is the mixture formed when a solute dissolves in a solvent. For example, when sugar dissolves in tea, it creates a sugar-tea solution.

What is the difference between solute and solvent?

The solute is the substance that is dissolved, while the solvent is the substance that does the dissolving. In a tea solution with sugar, sugar is the solute, and tea is the solvent.

Why do some substances dissolve in water while others do not?

The ability of a substance to dissolve in water depends on the polarity of the molecules. Polar substances dissolve in polar solvents (like water), while nonpolar substances do not.

What is solubility?

Solubility is the measure of how much solute can dissolve in a solvent at a given temperature and pressure. It is typically expressed in grams of solute per 100 milliliters of solvent.

How does temperature affect the solubility of solid solutes?

For solid solutes, an increase in temperature generally increases solubility. For example, as the temperature of water rises, more sugar can dissolve in it.

How does temperature affect the solubility of gases?

For gases, the solubility decreases as the temperature increases. This means that warmer water will hold less dissolved gas, such as CO2 in lemonade.

Why do bubbles form when opening a bottle of carbonated lemonade?

Bubbles form because the solubility of carbon dioxide (CO2) in the lemonade decreases when the pressure is released. The CO2 comes out of solution and forms gas bubbles, creating the fizz.

How does pressure affect the solubility of gases in liquids?

As pressure increases, the solubility of gases in liquids also increases. This is why carbonation is maintained during bottling under pressure, keeping CO2 dissolved in the beverage.