To determine which is the stronger acid, we need to look at the properties of H2O (water) and H3O+ (hydronium ion).
H2O, in its pure form, can act as a very weak acid. It can donate a proton (H+) to another water molecule, forming OH- (hydroxide ion) and H3O+. However, its ability to donate protons is limited, placing it on the weaker side of the acid scale.
On the other hand, H3O+ is the ion formed when water donates a proton, making it a much stronger acid. In acid-base chemistry, the strength of an acid is often measured by its ability to donate protons. H3O+, therefore, has a higher concentration of protons and significantly enhances the acidity of the solution.
In summary, H3O+ is indeed a stronger acid than H2O. The presence of the extra proton not only makes H3O+ more reactive in terms of proton donation but also leads to a greater acidity in solution.