Henry law Class 12: It is essential for Class 12 students studying Chemistry. This law explains how the solubility of gases in liquids depends on pressure, a concept that’s highly relevant in both theoretical and practical scenarios. Let’s dive into the details of Henry’s Law, including its statement, formula, applications, and solved examples, in simple and easy-to-understand language.
What is Henry law Class 12?
Henry’s Law describes the relationship between the pressure of a gas and its solubility in a liquid. In simple terms, it states that the higher the pressure above a liquid, the more gas will dissolve in it.
For example, the fizz in soda bottles is because of carbon dioxide gas dissolved in the liquid under high pressure. When you open the bottle, the pressure decreases, and the gas escapes.
Statement of Henry law Class 12
The statement of Henry’s Law is as follows:
“The amount of gas dissolved in a liquid is directly proportional to the partial pressure of the gas above the liquid at a constant temperature.”
This means that if you increase the pressure of the gas above the liquid, more of it will dissolve into the liquid.
Formula of Henry law Class 12
The mathematical expression of Henry’s Law is: pgas ∝ χgas
Pgas = kH.χgas
Where:
χgas = Concentration of the gas as mole fraction(solubility) in the liquid.
kH = Henry’s constant (depends on the nature of gas and liquid and the temperature).
Pgas = Partial pressure of the gas.
The value of Henry’s constant changes with temperature. For instance, as the temperature increases, gases become less soluble in liquids, which is why soda goes flat faster when it’s warm.
Factors Affecting Henry law Class 12
There are several factors which influence the solubility of gases as explained by Henry’s Law:
- Nature of the Gas: Gases like carbon dioxide dissolve more easily in liquids compared to less soluble gases like oxygen.
- Temperature: Higher temperatures reduce the solubility of gases in liquids.
- Pressure: Increased pressure increases the gas solubility in liquids, as per Henry’s Law.
Applications of Henry law Class 12
Henry’s Law has many practical and useful applications. They are followings:
- Carbonated Beverages: Soda and soft drinks are bottled under high pressure to dissolve carbon dioxide gas. Opening the bottle releases the pressure, causing the gas to escape.
- Scuba Diving: Divers breathe compressed air at high pressures underwater. According to Henry’s Law, more nitrogen dissolves in their blood under high pressure. If they ascend too quickly, nitrogen forms bubbles, leading to decompression sickness.
- Industrial Gas Purification: Henry’s Law is used to remove impurities like oxygen or carbon dioxide from gases in industries.
- Biological Systems: The law explains how gases like oxygen and carbon dioxide dissolve in blood during respiration.
Limitations of Henry law Class 12
Although Henry’s Law is applicable at large scale, it has certain limitations also:
- It doesn’t apply to gases that chemically react with the liquid, like ammonia in water.
- It’s valid only under moderate pressure and temperature. Extreme conditions can lead to deviations.
Solved Examples on Henry law Class 12
Example 1: A gas has a Henry’s constant of 4.5 × 10³ atm at 25°C. Calculate the solubility of the gas in water if the pressure above the liquid is 2 atm.
Solution:
Using the formula C = kP,
C = 4.5 × 10³ × 2 = 9 × 10³ mol/L.
Example 2: Why does soda go flat faster in warm conditions?
Answer: At higher temperatures, the solubility of gases in liquids decreases due to a lower Henry’s constant. This makes the carbon dioxide escape faster, leaving the soda flat.
Frequently Asked Questions (FAQs)
Why is Henry law Class 12 important?
Henry’s Law is crucial for understanding gas solubility, which is essential in industries, biology, and daily life.
How does temperature affect Henry’s Law?
Higher temperatures reduce gas solubility in liquids, as gases tend to escape more easily.
What are some common examples of Henry’s Law in action?
Carbonated drinks, scuba diving, and gas exchange in the human body are everyday examples.
Conclusion of Henry law Class 12
Henry’s Law is a simple yet powerful principle that explains the solubility of gases in liquids under pressure. Whether it’s the fizz in your soda or the science behind scuba diving, this law has wide-ranging applications. By mastering its statement, formula, and solved examples, you can easily tackle exam questions and understand real-world phenomena.
Read More: Notes of solution for chemistry 12th chapter two
Additional Resources
Gas Laws and Their Applications
Surface Chemistry Class 12 Notes
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