Question

Which of the following is not correct about the adsorption?

• A. Physical adsorption is not specific in nature.
• B. In adsorption, $\Delta G$, $\Delta S$ and $\Delta H$ are negative.
• C. $\mathrm{C_2H_5OH}$ acts as an auto catalyst in the hydrolysis of ethyl acetate.
• D. In Freundlich adsorption isotherm $\frac{x}{m} = k P^{\frac{1}{n}}$, the value of $-\frac{1}{n}$ is between 0 to 1.

Hint:

Always verify the role of substances in chemical reactions. Not all compounds that are involved in a reaction contribute as catalysts—many serve as solvents or reactants without altering the reaction rate.

Answer 1

The Correct Option is C

To solve the problem, we need to identify the incorrect statement about adsorption.

1. Understanding Adsorption:
Adsorption is the process by which molecules or atoms adhere to a surface. There are various types of adsorption, such as physical and chemical adsorption, and they follow different thermodynamic principles.

2. Analyzing the Statements:

Physical adsorption is not specific in nature: This statement is correct. Physical adsorption is generally non-specific, meaning it can occur between a variety of adsorbents and adsorbates. It does not involve chemical bonds, just weak van der Waals forces.
In adsorption, \( \Delta G \), \( \Delta S \), and \( \Delta H \) are negative: This statement is generally true for physical adsorption. For spontaneous adsorption, \( \Delta G \) (Gibbs free energy) must be negative, and \( \Delta H \) (enthalpy) is also negative due to exothermic nature. \( \Delta S \) (entropy) is typically negative because the adsorbed molecules become more ordered on the surface.
\( C_2H_5OH \) acts as an auto catalyst in the hydrolysis of ethyl acetate: This is the incorrect statement. Ethanol (\( C_2H_5OH \)) is not an auto catalyst in the hydrolysis of ethyl acetate. In fact, the hydrolysis of ethyl acetate requires a catalyst like an acid or base, but not ethanol itself as an auto catalyst.
In Freundlich adsorption isotherm, \( \frac{x}{m} = k \cdot P^{1/n} \), the value of \( \frac{1}{n} \) is between 0 and 1: This statement is correct. In the Freundlich isotherm, \( \frac{1}{n} \) is typically between 0 and 1, indicating that adsorption is not perfectly linear.

3. Final Answer:
The incorrect statement is the one related to ethanol (\( C_2H_5OH \)) acting as an auto catalyst in the hydrolysis of ethyl acetate.

Final Answer:
The correct option is (C) \( C_2H_5OH \) acts as auto catalyst in the hydrolysis of ethyl acetate.