Which type of substance would have a pH close to 7?

Substances that have a pH close to 7 are generally considered neutral. The pH scale ranges from 0 to 14, where a pH of 7 is the midpoint, indicating a neutral solution. Pure water is the classic example of a neutral substance, as it neither donates protons (H⁺ ions) like an acid nor accepts them like a base.

Acids typically have pH values below 7 due to the presence of excess hydrogen ions, while bases have pH values above 7 because they either produce hydroxide ions (OH⁻) or decrease the concentration of hydrogen ions in a solution. Toxic chemicals can vary widely in their pH but are not specifically tied to a pH value of 7.

Understanding this balance in pH is crucial in many scientific applications, from determining the acidity or alkalinity of solutions in chemistry to assessing the health of ecosystems in environmental science. Therefore, recognizing that neutral substances are characterized by a pH around 7 is fundamental in the study of chemistry and its practical applications.