Final answer:
The lower the pH, the higher the hydroxide ion (OH-) concentration. pH is inversely related to the concentration of hydroxide ions in a solution, with a decrease in pH signifying an increase in hydroxide ion concentration.
Step-by-step explanation:
The lower the pH, the higher the OH- concentration. In the context of acidity and basicity in chemical solutions, the pH scale is used to determine how acidic or basic a solution is. A pH value lower than 7 indicates an acidic solution and is characterized by a higher concentration of hydronium ions (H3O+). As the pH decreases, which means the solution becomes more acidic, the concentration of hydroxide ions (OH-) must increase due to the relationship between H3O+ and OH- concentrations, as their product is constant at 1.0×10-14 at 25 °C. Consequently, a lower pH correlates with a higher OH- concentration due to the inverse relationship between the concentrations of hydronium ions and hydroxide ions.