Understanding Solution Terminology

Key Terms

1. Molarity (M)

   • Definition: Moles of solute per liter of solution.
   • Usage: Describes concentration of a solution.

2. Molality (m)

   • Definition: Moles of solute per kilogram of solvent.
   • Key Difference: Uses mass (kg) of solvent instead of volume (liter) of solution.

3. Osmolarity

   • Definition: Osmoles of solute per liter of solution.
   • Note: Osmoles account for particles that ionize or disassociate (e.g., salt).

4. Osmolality

   • Definition: Osmoles of solute per kilogram of solvent.
   • Key Difference: Like molality, it uses mass (kg) of solvent.

5. Tonicity

   • Definition: Describes the relative concentration of solutions separated by a membrane.
   • Types:
     • Hypotonic: Lower solute concentration outside the cell.
     • Isotonic: Equal solute concentration.
     • Hypertonic: Higher solute concentration outside the cell.

Differences & Relationships

• Molarity vs. Molality: Difference lies in the denominator (volume vs. mass).
• Osmolarity vs. Osmolality: Difference also lies in the denominator but involves osmoles, not moles.
• Purpose of Tonicity: Used to compare two solutions, especially with biological membranes (e.g., cell membranes).

Application in Medicine

• Medical Relevance: These terms are crucial for describing and understanding solutions in medical contexts.
• Cellular Context: Used to discuss the movement of water and solutes across cell membranes.
• Common Scenarios: Blood plasma, interstitial fluid, and intracellular environments are typical contexts.

Summary

• Single Solution Terms: Molarity, Molality, Osmolarity, Osmolality.
• Comparative Term: Tonicity for comparing solutions across membranes.
• Framework: These terms help in understanding solute-solvent interactions and their effects in biological settings.