Why dissolving gases in the liquids is exothermic while the phase is down ? explain please
What does "when the phase is down" mean?
I mean the phase of the gas is going towards being liquid
I'm still not sure of the question so I'll restate it as I think you are asking. Why is the phase change from vapor to liquid exothermic?
My response and I'll use water as an example:
H2O(liquid) + heat ==> H2O(gas) which clearly is an endothermic reaction. BUT if yu run the same reaction in reverse it clearly gives off heat so the reaction MUST be exothermic.
When gases dissolve in liquid, the process can either be exothermic or endothermic. In the case of most gases dissolving in liquids, the process is exothermic, which means it releases heat. The exothermic nature of gas dissolution is independent of whether the phase is up or down. However, let's explore why dissolving gases in liquids is generally exothermic:
1. Molecular attractions: When a gas molecule comes into contact with a liquid, the attractive forces between the gas molecules and the liquid molecules play a significant role. These forces are predominantly intermolecular forces such as van der Waals forces or dipole-dipole interactions. These attractive forces pull the gas molecules into the liquid phase.
2. Increase in order: When a gas dissolves in a liquid, the gas molecules transition from a highly disordered state (gas phase) to a more ordered state (liquid phase). This increase in order or reduction in entropy is thermodynamically favorable. The process of increasing order releases energy and results in an exothermic reaction.
3. Energy release during solvation: When gas molecules dissolve in a liquid, they become surrounded by solvent molecules. This process is called solvation or hydration, depending on the type of liquid involved. The solvation process releases energy in the form of solvation energy or heat of solution. This energy is released as the attractive forces between the solvent and solute molecules are formed.
Overall, the exothermic nature of gas dissolution in liquids is due to the molecular attractions, increase in order, and the energy released during the solvation process. The term "phase is down" might refer to when the liquid is placed below the gas (e.g., a gas bubbling through a liquid). In this case, the exothermic nature of gas dissolution remains the same.