Inorganic Compounds and Their Properties

Inorganic Compounds

• Include water, salts, acids, and bases.

Water

• Most Abundant Inorganic Compound: 60%–80% of the volume of living cells.
• Most Important Inorganic Compound for biological functions.

Important Properties of Water

1. High Heat Capacity:
   • Ability to absorb and release heat with minimal temperature change.
2. High Heat of Vaporization:
   • Evaporation of water requires large amounts of heat, which helps in cooling processes (e.g., sweat evaporation).
3. Solvent Properties:
   • Dissolves and dissociates ionic substances (e.g., sodium chloride into Na+ and Cl- ions).
4. Role in Chemical Reactions:
   • Necessary for hydrolysis and dehydration synthesis reactions.
5. Protection:
   • Cushions and protects certain organs from physical trauma.

Salts

• Definition: Ionic compounds that dissociate into positive (cations) and negative (anions) ions in solution.
• Roles of Ions: Vital for body functions, including muscle contraction and nerve impulse conduction.
  • Example ions: Calcium (Ca²+), Phosphorus (P), Sodium (Na+), and Chloride (Cl-).

Acids

• Definition: Substances that dissociate in water to produce hydrogen ions (H+).
  • Considered proton donors.

Bases

• Definition: Substances that dissociate in water to produce hydroxide ions (OH-) and are considered proton acceptors.
  • Important bases in the body include bicarbonate ions (HCO₃⁻) and ammonia (NH₃).

Acid-Base Concentration (pH)

• pH Definition: Concentration of hydrogen ions (H+) in a solution.
  • Neutral (pH = 7): Equal concentrations of H+ and OH-.
  • Basic (pH > 7): Decreasing concentrations of H+, increasing concentrations of OH-.
  • Acidic (pH < 7): Increasing concentrations of H+, decreasing concentrations of OH-.

pH Examples

• pH Scale:
  • 1 M Hydrochloric acid: pH = 0 (strong acid)
  • Lemon juice/gastric juice: pH ≈ 2
  • Wine: pH ≈ 2.5–3.5
  • Black coffee: pH ≈ 5
  • Milk: pH ≈ 6.3–6.6
  • Blood: pH ≈ 7.4 (slightly basic)
  • Household ammonia: pH ≈ 10.5–11.5
  • 1 M Sodium hydroxide: pH = 14 (strong base)

Buffers

• Importance: Cells are sensitive to pH changes; maintaining acid-base balance is crucial for homeostasis.
• Function of Buffers:
  • Release hydrogen ions (H+) when pH rises too much.
  • Bind hydrogen ions when pH drops too low, helping to stabilize pH levels within cells and tissues.