What are some common mistakes students make with solutes?
The most common mistake I see students make with solutes is falling back on the very vague definition of a solute.
Solute-the substance with a smaller concentration in solution.
This is not always true.
More accurate definition:
The substance which is being dissolved is the solute, regardless of concentration.
Reasoning: It is not true to say that salt is dissolving water (saying salt is the solvent) merely because the concentration of salt is higher than that of water.
Water will always be dissolving the salt in this situation, therefore water will always be the solvent in this system.