Critical temperatures of N2, CO, CH4 are 126, 134, and 110 K respectively. Arrange them in increasing order of adsorption on the surface of activated charcoal?

To determine the order of adsorption of nitrogen (N2), carbon monoxide (CO), and methane (CH4) on activated charcoal, we need to consider their critical temperatures. The critical temperature of a substance is the highest temperature at which it can exist as a liquid, and it provides insight into the strength of intermolecular forces and the tendency of a gas to condense. Generally, gases with lower critical temperatures tend to have higher adsorption capacities on surfaces like activated charcoal.

Understanding Critical Temperatures

The critical temperatures for the gases in question are as follows:

• N2: 126 K
• CO: 134 K
• CH4: 110 K

From these values, we can see that methane (CH4) has the lowest critical temperature, followed by nitrogen (N2), and then carbon monoxide (CO) with the highest critical temperature. This trend suggests that methane is more likely to be adsorbed on activated charcoal compared to the other two gases.

Adsorption Characteristics

Adsorption is influenced by several factors, including the nature of the gas molecules and their interactions with the surface of the adsorbent. In the case of activated charcoal, which has a high surface area and porous structure, the following points are relevant:

• Molecular Size: Smaller molecules tend to diffuse into the pores of activated charcoal more easily, enhancing their adsorption.
• Polarity: The nature of intermolecular forces plays a role. Methane is non-polar, while CO has a slight polarity due to its dipole moment.
• Critical Temperature Influence: Gases with lower critical temperatures generally have weaker intermolecular forces, making them more prone to adsorption.

Arranging the Gases

Based on the critical temperatures and the factors influencing adsorption, we can arrange the gases in increasing order of their adsorption on activated charcoal:

• Carbon Monoxide (CO) - Highest adsorption
• Nitrogen (N2)
• Methane (CH4) - Lowest adsorption

In summary, the order of adsorption on activated charcoal from highest to lowest is CO, N2, and CH4. This arrangement reflects the relationship between critical temperature and adsorption capacity, where lower critical temperatures correlate with higher adsorption tendencies.