Which one of the following statements regarding Henry's law is not correct?
(a) Different gases have

Q: Why does $K_H$ increase with temperature?

As temperature increases, the kinetic energy of the dissolved gas molecules increases. This makes it easier for them to overcome intermolecular forces and escape into the vapor phase, effectively reducing solubility. Since solubility drops, $K_H$ must increase.

Q: Are $K_H$ values the same for all gases?

No, $K_H$ is highly dependent on the nature of the gas and the solvent. Gases that interact strongly with the solvent (like $NH_3$ in water) have lower $K_H$ values (higher solubility) compared to non-polar gases like $O_2$ or $N_2$.

Q: What are the units of $K_H$?

Since mole fraction ($\chi$) is dimensionless, the units of $K_H$ are the same as pressure, such as atm, bar, or Pascals.

Q: Does Henry's law apply at very high pressures?

No, Henry's Law is a limiting law. It is most accurate at low to moderate pressures. At very high pressures, gases deviate from ideal behavior, and the linear relationship breaks down.

Q: Why is option D considered a correct statement?

Option D is the literal definition of Henry's Law! It states that the partial pressure of the gas is directly proportional to its mole fraction in the solution, which is exactly what $P = K_H \cdot \chi$ represents.

Question

Which one of the following statements regarding Henry's law is not correct?

Options:

(A) Different gases have different $K_H$ (Henry's law constant) values at the same temperature

(B) Higher the value of $K_H$ at a given pressure, higher is the solubility of the gas in the liquids

(C) The value of $K_H$ increases with increase of temperature and $K_H$ is function of the nature of the gas

(D) The partial pressure of the gas in vapour phase is proportional to the mole fraction of the gas in the solution

Sigma Percentile · Accepted Answer

### The Essence of Henry's Law

Imagine you are holding a sealed bottle of your favorite carbonated drink. Above the liquid, there is a high-pressure gas, and inside the liquid, gas molecules are happily dissolved. This everyday phenomenon is perfectly described by **Henry's Law**.

Henry's Law states that the partial pressure ($P$) of a gas in the vapor phase is directly proportional to its solubility, often expressed as the mole fraction ($S$ or $\chi$), in the solution.

Mathematically, we write this as:

$$P = K_H \cdot S$$

Here, $K_H$ is the Henry's law constant. It is a unique signature for every gas at a specific temperature.

### Decoding the Relationship

To truly understand what $K_H$ tells us, let's rearrange our master equation to solve for solubility ($S$):

$$S = \frac{P}{K_H}$$

Look closely at this equation. If we keep the pressure ($P$) constant, the solubility ($S$) is **inversely proportional** to Henry's constant ($K_H$).

What does this mean physically? You can think of $K_H$ as a measure of a gas's "reluctance" to dissolve. A higher value of $K_H$ means the gas is more stubborn; it prefers to stay in the vapor phase rather than mixing into the liquid. Therefore, a higher $K_H$ results in a **lower** solubility.

### Evaluating the Statements

Now, let's look at the options provided in the question. Option (b) claims: *"Higher the value of $K_H$ at a given pressure, higher is the solubility of the gas in the liquids."*

Based on our derived inverse relationship ($S \propto \frac{1}{K_H}$), this statement is completely backwards! A higher $K_H$ actually means *lower* solubility. Thus, statement (b) is the incorrect one.

As a bonus insight, remember that increasing the temperature gives gas molecules more kinetic energy, making them more likely to escape the liquid. This means $K_H$ increases with temperature, which is exactly why warm soda goes flat so quickly!

Animated Solution for Chemistry - Solutions: Which one of the following statements regarding Henry's law is not correct?

Select Answer:

Visualized Solution

$P \propto S$

$P = K_{H} \cdot S$

$S = \frac{P}{K _{H}}$

$S \propto \frac{1}{K _{H}}$

$K_{H} ↑ ⟹ S ↓$

$T ↑ ⟹ K_{H} ↑ ⟹ S ↓$

The Sigma Insight: Henry's Law and Raoult's Law

The Essence of Henry's Law

Decoding the Relationship

Evaluating the Statements

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