Tuesday, July 30, 2019

aqueous solution - Does the amount of solute affect rate of solvation?


I know that in order to increase the rate of solvation, you need to increase how often solute and solvent particles come into contact.


You can do it by:




  1. agitating the mixture

  2. increasing the surface area of the solute

  3. heating up the solvent


But my question is: Does adding more solute (like adding more salt to water) increase the rate of solvation since the contact surface area is larger?


Edit: The original question in the book describes dissolving a certain amount of NaCl into water and asks, “What can be done to increase the rate of dissolution without affecting solubility?” I assume the rate is measured by how fast the mass of NaCl is consumed, which is dWdt.



Answer



If the answers are to be exclusive, then obvious choice is agitating the mixture.


If the answers are not to be exclusive, then agitating the mixture + increased surface by adding more solute increases dcdt


Adding more solute does not increase rate of solvation, but as the absolute surface increases, it increases dcdt.



Note also without affecting solubility from your comment, so increasing temperature is out.


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