SCB203 - L5 Water, Acids, Bases and Salts

Lecture Overview

  • Lecture 5: Focuses on Inorganic Compounds, Water, Acids, Bases, and Salts

Key Definitions

  • Inorganic Compounds: Generally do not contain carbon bonded to hydrogen. Examples include water, acids, bases, and salts.

  • Organic Compounds: Compounds that contain carbon bonded to hydrogen.

Essential Inorganic Compounds

  • Water: Vital for life, exhibiting unique properties due to its polar nature.

  • Salts: Formed from a metal cation and a non-metal anion, dissociate in solution to form electrolytes, essential for various bodily functions.

Properties of Water

  • Absorbs Heat:

    • Temperature remains stable despite heat absorption.

    • Plays a role in temperature regulation in organisms (e.g., walking in the desert without harm).

  • Carries Heat:

    • Sweating cools the body via evaporative cooling.

    • Humidity affects evaporation, making it feel hotter.

  • Cushions and Protects:

    • High density provides buoyancy, protecting the brain and organs suspended within it.

  • Acts as a Lubricant:

    • Water reduces friction between surfaces, found in serous membranes around organs.

Water as a Solvent

  • Universal Solvent:

    • Many solutes dissolve in water due to its molecular structure and polarity.

    • Hydrophilic Solutes: Attract water, fully or partially charged (e.g., ionic compounds like salts).

    • Hydrophobic Solutes: Lack charged ends; do not dissolve in water (e.g., oils, fats).

Acids and Bases

  • Acids:

    • Defined as hydrogen ion donors (e.g., hydrochloric acid: HCl).

    • Release H+ ions into solution, increasing acidity.

  • Bases:

    • Defined as hydrogen ion acceptors (e.g., sodium bicarbonate: NaHCO3).

    • Decrease H+ concentration by binding to free H+ ions.

pH Scale

  • pH Definition:

    • Represents hydrogen ion concentration in solution; calculated as pH = -Log [H+].

  • Scale Range: 0 to 14, with lower values indicating higher acidity and higher values indicating higher alkalinity.

  • Neutral pH: Around 7, where concentrations of H+ and OH- are equal.

Buffer Systems

  • Buffers:

    • Mixtures of weak acids and their salts that maintain stable pH levels in body fluids.

    • Example: Bicarbonate buffer system, which counters changes in blood pH to prevent acidosis (pH < 7.35) or alkalosis (pH > 7.45).

  • Function: Help absorb excess H+ or OH- to stabilize pH in biological systems.

Important Concepts to Review

  • Distinction between organic and inorganic compounds.

  • The critical role of water and salts in physiological processes.

  • Properties of acids, bases, and salts.

  • Understanding and applying the pH scale.

  • Mechanisms of buffer systems in maintaining homeostasis.