Intro to Henry's Law: Videos & Practice Problems

Henry's law states that the solubility of a gas in a liquid is directly proportional to the gas's partial pressure above the liquid. Increasing pressure enhances gas solubility, while higher temperatures decrease it. For solids, increased temperature boosts solubility. This relationship is crucial for understanding gas behavior in solutions and the impact of temperature on solute dissolution. Remember, pressure changes do not affect solids or liquids, emphasizing the unique behavior of gases in solution dynamics.

Intro to Henry's Law Concept 1

Henry's law describes the relationship between the solubility of a gas in a liquid and the partial pressure of that gas above the liquid. According to this law, the solubility of a dissolved gas is directly proportional to its partial pressure. This relationship can be understood through two key aspects: the pressure solubility relationship and the temperature solubility relationship.

When pressure is applied to a closed container with a liquid and gas, the solubility of the gas increases. For instance, if you imagine a piston pushing down on the gas above the liquid, the increased pressure forces more gas molecules into the liquid, enhancing their solubility. It is crucial to note that changes in pressure do not affect the solubility of solids or liquids; this principle specifically applies to gases.

On the other hand, temperature also plays a significant role in solubility. As temperature rises, the solubility of a gas decreases. A practical example is boiling water in a closed pot: as the water heats up, gas molecules escape as steam, indicating that their solubility is diminishing. Conversely, for solids, an increase in temperature generally leads to an increase in solubility. For example, heating a hard substance in water can cause it to dissolve more readily as the temperature rises, breaking down the solid into its constituent parts.

In summary, Henry's law highlights that while increasing pressure enhances the solubility of gases, increasing temperature decreases gas solubility but increases the solubility of solids. Understanding these relationships is essential for applications in chemistry and various scientific fields.

Intro to Henry's Law Example 1

Understanding the relationship between temperature and solubility is crucial in chemistry. Generally, as temperature increases, the solubility of gases in liquids decreases. This phenomenon occurs because higher temperatures provide gas molecules with more energy, allowing them to escape from the liquid more easily. For instance, when you heat a carbonated beverage, the gas bubbles start to form and escape, leading to a decrease in gas solubility.

Conversely, the solubility of most solids in liquids tends to increase with rising temperatures. This is because increased thermal energy helps to break down the solid structure, allowing more solute to dissolve in the solvent. A practical example is dissolving sugar in hot water; the sugar dissolves more readily at higher temperatures.

In summary, the key takeaway is that while the solubility of gases decreases with increasing temperature, the solubility of solids typically increases. This dual behavior highlights the importance of temperature in solubility dynamics, making it essential for various applications in chemistry and related fields.

Which of the following is true for the solubility of NaCl (s) and CH₄ (g) in water?  

• A. Increasing the temperature will increase the solubility of CH₄.
• B. Increasing the temperature will decrease the solubility of NaCl.
• C. Both NaCl and CH₄ are quite soluble in water.
• D. Neither NaCl nor CH₄ are soluble in water.
• E. None of the above.

Answer: (E)

Here’s what students ask on this topic:

What is Henry's Law and how does it relate to gas solubility?

Henry's Law states that the solubility of a gas in a liquid is directly proportional to the partial pressure of that gas above the liquid. Mathematically, it can be expressed as:

$C=kP$

where $C$ is the concentration of the gas in the liquid, $k$ is the Henry's Law constant, and $P$ is the partial pressure of the gas. This means that if you increase the pressure of the gas above the liquid, more gas will dissolve in the liquid. Conversely, if the pressure decreases, the gas solubility will also decrease.

How does temperature affect the solubility of gases according to Henry's Law?

According to Henry's Law, the solubility of gases in a liquid decreases as the temperature increases. This is because higher temperatures provide more kinetic energy to gas molecules, making them more likely to escape from the liquid into the gas phase. For example, when you heat water, you observe steam, which is gas escaping from the liquid. Therefore, increasing temperature reduces the solubility of gases in liquids.

Why does increasing pressure increase the solubility of a gas in a liquid?

Increasing pressure increases the solubility of a gas in a liquid because it forces more gas molecules into the liquid phase. When you apply pressure to a gas above a liquid, you effectively push more gas molecules into the liquid, where they become dissolved. This is why carbonated beverages are bottled under high pressure to keep the carbon dioxide dissolved in the liquid. When the pressure is released, such as when you open the bottle, the gas escapes, and the beverage becomes flat.

Does Henry's Law apply to solids and liquids?

No, Henry's Law specifically applies to gases. Changes in pressure do not affect the solubility of solids or liquids. However, temperature changes can affect the solubility of both solids and gases. For solids, increasing the temperature generally increases their solubility in a liquid. For gases, increasing the temperature decreases their solubility. This distinction is important for understanding the unique behavior of gases in solution dynamics compared to solids and liquids.

What is the relationship between temperature and the solubility of solids?

The solubility of solids in a liquid generally increases with an increase in temperature. When you heat a solution, the increased kinetic energy helps break down the solid particles, allowing them to dissolve more readily in the solvent. For example, sugar dissolves more quickly in hot water than in cold water. This is because the higher temperature provides the energy needed to overcome the forces holding the solid particles together, making them more soluble.