Let’s take a look at the difference between isotonic, hypertonic, and a hypotonic solution. To begin with, it’ll be helpful to know the difference between a solvent and a solute. Let’s look at an example, a cup of coffee. The solvent is what the solute is dissolved into. The water is the solvent and the cream, sugar, and coffee are solutes.

solute solvent

An isotonic solution means it has equal strength. Iso means equal and tonic means strength. The solute and the solvent will travel in and out of the cell equally and the cell will stay the same. 


A hypertonic solution has above strength. Hyper means above, and tonic means strength. If you have a cell with a higher concentration of solvent inside the cell, the solution is hypertonic, and the solvent travels out of the cell and the cell will shrink. The solvent always travels from high concentration to low concentration.


 Now hypotonic means below strength. It consists of hypo meaning below, and tonic meaning strength. If you have a cell with very little solute outside the cell and a higher concentration of solvent outside the cell the solution inside the cell will be hypotonic and the solvent will flow into the cell. Remember solvent travels from  high to low concentration and the cell will expand.


So in summary, isotonic is equal, hypertonic is above, and hypotonic is below.


In a solution, the solute is the substance that is dissolved in the solvent. The solvent is the substance that does the dissolving.

Some key differences between solutes and solvents include:

  • Solute:
    • Is present in a smaller amount than the solvent
    • Is usually a solid, liquid, or gas
    • Can be dissolved in a variety of solvents
  • Solvent:
    • Is present in a larger amount than the solute
    • Is usually a liquid or gas
    • Can dissolve a variety of solutes

Examples of solutes and solvents:

  • Solute: salt, sugar, baking soda
  • Solvent: water