Understanding pH in Biology and Chemistry

May 23, 2024

Mindmap

Acids, Bases, and pH

Introduction

  • Measurements related to pH:
    • pH measures whether something is acidic or basic.
    • Water has a pH of 7.
    • Acids have a pH less than 7 and bases have a pH greater than 7.
  • Importance of pH in biology:
    • Myoglobin protein is most active at a pH of 6.
    • If the pH changes significantly, proteins can denature and our muscles won't function.

Concept of pH

  • Relationship with water:
    • Water is composed of two hydrogen atoms and one oxygen atom.
    • The molecule is polar where the oxygen pulls electrons towards it forming a partial negative charge and the hydrogen a partial positive charge.
    • The molecules bond with each other through hydrogen bonds.
  • The separation of hydrogen and the formation of a hydronium ion (H3O+).
  • pH indicates the amount of hydronium or free hydrogen ions in water.
  • In distilled water, the likelihood of forming hydronium is very low (1 in 10,000,000).

pH Equation

  • pH is known as "power of hydrogen" or the amount of hydronium.
  • Equation: pH = -log[H+]
  • In pure water, the molar concentration of hydrogen ions is 1 ร— 10^-7, giving pH = 7.
  • Interpretation of pH:
    • pH = 7 represents neutrality.
    • pH > 7 is considered a base.
    • pH < 7 is considered an acid.

Examples of Acids and Bases

  • Hydrochloric acid (HCl) in the stomach:
    • Dissociates into hydrogen ions (H+) and chloride ions (Cl-), increasing the concentration of H+ and lowering the pH to around 2-1.
  • Sodium hydroxide (NaOH) as a base:
    • Dissociates into sodium ions (Na+) and hydroxide ions (OH-).
    • OH- combines with H+ to form water, reducing the concentration of H+ and raising the pH.

Effects of pH

  • pH is important for maintaining balance in biological environments:
    • Acid rain and ocean acidification as examples of the impact of pH changes.
    • Ocean acidification results from increased carbon dioxide forming carbonic acid.
    • pH changes deeply affect marine life and coral reefs.

Conclusion

  • pH is a very important measurement in chemistry and biology.
  • Understanding the chemical structure of water and its reactions helps explain the importance of pH.
  • pH affects the biological balance in the body and the environment.