Chemical Reactions and Properties of Water

Chemical Reactions and Water

• Chemical reactions transform reactants into products.
• Many reactions occur in aqueous environments, crucial for life.
• Water is the primary solvent in most biological reactions.
• Reactions often require energy input and enzymes.
• Reactions usually trend towards equilibrium, but external factors can shift this.

Properties of Water

• Water is a polar molecule, with partial positive and negative charges.
• Polarity allows water to dissolve ionic and polar substances.
• Hydrophilic molecules interact well with water; hydrophobic molecules do not.
  • Amphipathic molecules have both hydrophilic and hydrophobic parts.
• Water's polarity and hydrogen bonding are key to its dissolving power.
• Salt dissolves in water as water molecules pull apart the ions.

States and Functions of Water

• Water exists as a solid, liquid, and gas, with liquid being most common in biological systems.
• Hydrogen bonds in water require substantial energy to break, impacting its thermal behaviour.
• Water plays roles in:
  • Providing structural support.
  • Aiding in waste removal.
  • Temperature regulation.

Acids, Bases, and pH

• Acids release hydrogen ions, increasing their concentration.
• Bases reduce hydrogen ion concentration.
• pH measures hydrogen ion concentration.

pH Scale and Hydrogen Ion Concentration

• pH 7 is neutral (like pure water).
• The pH scale is logarithmic; a one-unit change equals a tenfold change in hydrogen ion concentration.
• Lower pH indicates higher hydrogen ion concentration (acidic).
• Higher pH indicates lower hydrogen ion concentration (basic/alkaline).

Importance of pH in Biological Systems

• pH affects cellular processes and enzyme function.
• Homeostatic mechanisms maintain optimal pH levels for cells.
• These mechanisms prevent drastic pH changes from disrupting cellular activities.
• Buffers help maintain stable pH.

Buffers and pH Regulation

• Buffers minimize pH changes by neutralizing added acids or bases.
• Chemical flexibility of buffers helps maintain stability.

Carbon and Organic Molecules

• Carbon forms four covalent bonds, essential for complex molecules.
• This capability allows diverse organic structures.
• Carbon is the basis of many important organic molecules.

Hydrocarbons and Functional Groups

• Hydrocarbons are non-polar and hydrophobic.
• Functional groups give specific properties (reactivity and interactions) to molecules.
• Examples of functional groups include hydroxyl, carboxyl, and amino.