Final answer:
The pH of a 0.1 M HCl solution is 1 because HCl is a strong acid that fully ionizes in water. The pH of a 0.1 M acetic acid solution is greater than 1 because acetic acid is a weak acid that only partially ionizes in water.
Step-by-step explanation:
The pH of a solution is determined by the concentration of hydrogen ions (H+). The lower the pH, the higher the concentration of H+. In a 0.1 M HCl solution, HCl is a strong acid that fully ionizes in water to produce H+ ions. Therefore, the concentration of H+ is equal to the concentration of HCl, which is 0.1 M, resulting in a pH of 1.
On the other hand, acetic acid (CH3COOH) is a weak acid that only partially ionizes in water to produce H+ ions. As a result, the concentration of H+ ions in a 0.1 M acetic acid solution is lower than 0.1 M. Therefore, the pH of a 0.1 M acetic acid solution is greater than 1, which in this case is around 2.879.