The chemical property that differentiates acids from bases is their pH level and how they react in solution. Acids release hydrogen ions (H⁺) when dissolved in water, resulting in a pH value below 7. Conversely, bases release hydroxide ions (OH⁻) and have a pH above 7. This distinction is crucial in chemistry, influencing reactions in biological systems, industrial processes, and environmental science, where pH balance is vital for health and ecological stability.