When water is added to an acetic acid solution, the total volume of the solution increases, but the concentration of the acetic acid remains the same.
Concentration is defined as the amount of solute (in this case, acetic acid) dissolved in a given amount of solvent (in this case, water). By adding water to the acetic acid solution, the total amount of solvent increases, but the amount of acetic acid remains constant.
For example, if you have a solution of acetic acid with a concentration of 1 M (moles per liter), adding water to it will increase the volume of the solution, but the concentration of acetic acid will still be 1 M.
However, if you remove water from the solution through evaporation or any other means, the total volume decreases, which can result in an increase in the concentration of acetic acid. The same amount of acetic acid is present in a smaller volume, leading to a higher concentration.
In summary, adding water to an acetic acid solution dilutes the solution, increasing its volume without changing the concentration of acetic acid.