Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
The pH scale measures how acidic or basic (alkaline) a substance is on a scale from 0 to 14. A pH value below 7 indicates acidity, while values above 7 indicate alkalinity. A neutral substance has a pH of 7.
Acid rain refers to rainfall that has become acidic due to the presence of pollutants like sulfur dioxide and nitrogen oxides in the atmosphere. It has a pH value below 5.6 and can harm ecosystems, buildings, and human health.
Buffer: A buffer is a substance or solution that helps maintain a stable pH by resisting changes when an acid or base is added. Buffers play a crucial role in regulating pH levels in biological systems.
Ocean acidification occurs when carbon dioxide from the atmosphere dissolves into seawater, lowering its pH. This process can have detrimental effects on marine life, especially organisms with calcium carbonate shells or skeletons.