Identify the appropriate graph between enthalpy and progress of physical adsorption.

Options

A.
B.
C.
D.

Explanation

To identify the appropriate graph between enthalpy and the progress of physical adsorption, we will follow these steps:

### Step 1: Understand Physical Adsorption
Physical adsorption is a process where molecules adhere to a surface through weak van der Waals forces. This process is typically exothermic, meaning it releases heat.

### Step 2: Recognize the Enthalpy Change
Since physical adsorption is exothermic, the change in enthalpy (ΔH) is negative. This can be expressed as:
\[ \Delta H = H_f - H_i \]
where:
- \( H_f \) is the final enthalpy after adsorption.
- \( H_i \) is the initial enthalpy before adsorption.

### Step 3: Determine the Relationship Between Initial and Final Enthalpy
For an exothermic process, the final enthalpy \( H_f \) will be less than the initial enthalpy \( H_i \):
\[ H_f < H_i \]
This indicates that the enthalpy decreases as the process progresses.

### Step 4: Sketch the Graph
On the graph:
- The x-axis represents the progress of adsorption.
- The y-axis represents the enthalpy.

Since \( H_f < H_i \), the graph will show a downward trend, indicating that enthalpy decreases as the adsorption progresses.

### Step 5: Identify the Correct Graph
Given the options, the correct graph would show a decreasing line from left to right, indicating that as the progress of physical adsorption increases, the enthalpy decreases.

### Conclusion
The appropriate graph for the enthalpy versus the progress of physical adsorption is a downward sloping line, indicating a decrease in enthalpy.