Adsorption is exothermic. True/False

Answer

**Step-by-Step Solution:**

1. **Understanding Adsorption**: Adsorption is a surface phenomenon where particles from a gas or liquid adhere to the surface of a solid or liquid (known as the adsorbent). This process is distinct from absorption, where a substance is taken up into the volume of another.

2. **Energy Changes During Adsorption**: When particles adhere to the surface of an adsorbent, the residual forces on the surface of the adsorbent decrease. This reduction in forces leads to a decrease in surface energy.

3. **Heat Release**: The decrease in surface energy during adsorption results in the release of energy in the form of heat. This is a key characteristic of exothermic processes, where energy is released to the surroundings.

4. **Entropy Considerations**: During adsorption, the randomness or disorder (entropy) of the system decreases because the adsorbate particles become more ordered when they adhere to the surface. This results in a negative change in entropy (ΔS < 0).

5. **Gibbs Free Energy**: For a process to be spontaneous, the change in Gibbs free energy (ΔG) must be negative. The relationship between ΔG, ΔH (enthalpy change), and ΔS is given by the equation:
\[ ΔG = ΔH - TΔS \]
Since ΔS is negative, for ΔG to remain negative, ΔH must also be negative, indicating that the process is exothermic.

6. **Conclusion**: Based on the above points, we can conclude that adsorption is indeed an exothermic process. Therefore, the statement "Adsorption is exothermic" is **True**.

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