Henry’s Law and Its Applications

 

Henry’s Law and Its Applications

Statement of Henry’s Law:

• The solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid.

Applications of Henry’s Law

1. Soft Drinks and Soda Water:

   • To increase the solubility of CO₂ in soft drinks and soda water, bottles are sealed under high pressure.

2. Scuba Diving:

   • Scuba divers breathe air at high pressure underwater, leading to increased solubility of atmospheric gases in blood.
   • As divers ascend, the pressure decreases, causing dissolved gases (especially nitrogen) to form bubbles in the blood.
   • These bubbles can block capillaries, leading to a painful and dangerous condition called bends.
   • To avoid bends and the toxic effects of nitrogen, scuba tanks are filled with a mixture of helium (11.7%), nitrogen (56.2%), and oxygen (32.1%) instead of normal air.

3. High Altitudes and Anoxia:

   • At high altitudes, the partial pressure of oxygen is lower than at sea level.
   • This results in lower oxygen concentrations in blood and tissues, causing anoxia, a condition where climbers become weak and experience difficulty in thinking clearly.

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Effect of Temperature on Gas Solubility

• The solubility of gases in liquids decreases with an increase in temperature.
• Dissolution of gases is an exothermic process (releases heat).
• According to Le Chatelier’s Principle, increasing temperature shifts the equilibrium to minimize the effect, reducing gas solubility.

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Here are 10 important and trending CBSE board questions based on Henry’s Law and gas solubility:

Concept-Based Questions:

1. State Henry’s Law. How does it explain the increase in the solubility of CO₂ in soda water when the bottle is sealed under high pressure?
2. How does Henry’s Law help in understanding the problems faced by scuba divers? Explain the condition called "bends."
3. Why do mountaineers suffer from anoxia at high altitudes? Explain with reference to Henry’s Law.
4. Why do scuba divers use a mixture of helium, nitrogen, and oxygen instead of normal air?
5. How does temperature affect the solubility of gases in liquids? Explain using Le Chatelier’s Principle.

Numerical and Application-Based Questions:

6. The solubility of oxygen in water at 293 K is 0.048 g/L when the partial pressure of oxygen is 0.21 atm. What will be the solubility of oxygen in water if the partial pressure increases to 0.35 atm? (Use Henry’s Law constant for oxygen at 293 K = 0.24 L·atm/g)
7. Why do cold drinks fizz when the bottle is opened? Explain using Henry’s Law.
8. Why is it dangerous to heat carbonated drinks in sealed bottles?
9. How does an increase in temperature affect aquatic life in rivers and lakes with respect to gas solubility?
10. Why do deep-sea fishes die when brought rapidly to the surface of the ocean? Explain in terms of gas solubility.

These questions cover definitions, applications, real-life examples, and numerical problems, ensuring a comprehensive understanding of the topic for CBSE board exams.

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