What is defined as an excess of H+ ions?

The definition of an excess of H+ ions relates directly to the characterization of solutions in terms of their acidity. When a solution has a high concentration of hydrogen ions (H+), it corresponds to a lower pH value. This increased presence of H+ ions is what defines a solution as acidic.

In the context of chemistry, solutions with a pH lower than 7 are considered acidic, indicating the dominance of H+ ions. This is fundamental in acid-base chemistry, where acids are identified by their ability to donate H+ ions in a solution, further reinforcing the concept that solutions with excess H+ ions are inherently acidic.

In contrast, solutions that are neutral have an equal concentration of H+ and hydroxide ions (OH-), resulting in a pH of 7. Alkaline solutions, also known as basic solutions, have a lower concentration of H+ ions compared to OH- ions, leading to a pH greater than 7. Sour typically describes the taste of acidic solutions but does not define the concept of H+ ion excess explicitly. Thus, the answer highlighting the presence of an excess of H+ ions is indeed acidic, confirming the understanding of acidity in relation to hydrogen ion concentration.