PH scale

Definition

The pH scale is a logarithmic scale used to measure the acidity or alkalinity of a solution, ranging from 0 to 14. A pH value of 7 is considered neutral, values below 7 indicate acidity, and values above 7 indicate alkalinity. The scale is crucial in understanding acid-base chemistry and its applications in various biological and chemical processes.

5 Must Know Facts For Your Next Test

1. The pH scale is logarithmic, meaning each whole number change on the scale represents a tenfold change in acidity or alkalinity.
2. A pH of 0 is highly acidic, while a pH of 14 is highly alkaline; the majority of biological systems operate best within a narrow range around pH 7.
3. The pH of blood is tightly regulated around 7.4, and deviations from this range can have significant physiological effects.
4. Indicators are substances that change color at specific pH levels, and they are often used to determine the acidity or alkalinity of a solution.
5. The concept of pH was introduced by Danish chemist Søren Sørensen in 1909 as a way to quantify acidity.

Review Questions

• How does the logarithmic nature of the pH scale influence our understanding of acidity and alkalinity in solutions?
  • The logarithmic nature of the pH scale means that each unit change represents a tenfold increase or decrease in hydrogen ion concentration. This allows for a more intuitive grasp of how dramatically different solutions can be in terms of acidity or alkalinity. For instance, a solution with a pH of 4 is ten times more acidic than one with a pH of 5, making it essential for accurately comparing acidic environments in biological systems.
• Discuss how buffers work to maintain pH levels in biological systems and why this is important.
  • Buffers are critical in maintaining stable pH levels within biological systems, as they resist changes when acids or bases are added. For example, bicarbonate acts as a buffer in blood, neutralizing excess acids and helping to keep the blood's pH around 7.4. This stability is vital because many biochemical processes are sensitive to changes in pH, ensuring that enzymes function optimally and cellular processes proceed without disruption.
• Evaluate the implications of extreme pH values on living organisms and their metabolic functions.
  • Extreme pH values can have dire consequences for living organisms, affecting enzyme activity and metabolic functions. For instance, if the pH falls below 6.8 or rises above 7.8, it can disrupt cellular processes, leading to dysfunction or even cell death. These alterations can affect physiological processes such as respiration and metabolism, showcasing the importance of maintaining a balanced pH for overall health and biological integrity.

Related terms

Acids: Substances that donate protons (H\(^+\,\)) to a solution and have a pH less than 7.

Bases: Substances that accept protons or donate hydroxide ions (OH\(^-\,\)) in a solution, resulting in a pH greater than 7.

Buffers: Solutions that resist changes in pH upon the addition of small amounts of acids or bases, helping to maintain a stable environment.