What is the formula used to calculate the pH of a solution?

• A. pH = log[H⁺]
• B. pH = [-1]log[H⁺]
• C. pH = -log[H⁺]
• D. pH = H⁺/[H₂O]

Answer: (C)

The correct formula for calculating the pH of a solution is pH = -log[H⁺]. This relationship is based on the concentration of hydrogen ions ([H⁺]) in a solution. The negative sign indicates that as the concentration of hydrogen ions increases (meaning a more acidic solution), the pH value decreases, reflecting the inversely logarithmic nature of the pH scale.

This pH scale ranges from 0 to 14 in most cases, where a pH of 7 is considered neutral. Lower pH values (below 7) indicate acidic solutions, while higher values (above 7) represent basic solutions. The logarithmic scale means that each whole number change in pH corresponds to a tenfold change in [H⁺] concentration.

The other choices do not accurately reflect the calculation of pH. The formula pH = log[H⁺] would suggest that as [H⁺] increases, pH would increase, which contradicts the definition of pH. The formula pH = H⁺/[H₂O] does not directly relate to pH and would not yield a value characteristic of the pH scale, as it confuses the concept of concentration with