1. Dissociation:
* Sodium chloride (NaCl): Is an ionic compound that dissociates into two ions (Na+ and Cl-) when dissolved in water. This means one molecule of NaCl produces two particles in solution.
* Glucose (C6H12O6): Is a covalent compound that does not dissociate in water. One molecule of glucose remains as a single particle in solution.
2. Osmotic Pressure:
* Osmotic pressure is the pressure required to prevent the inward flow of water across a semipermeable membrane. It's directly proportional to the concentration of solute particles.
* NaCl: Due to its dissociation, a 1M solution of NaCl produces 2M of solute particles. This results in a higher osmotic pressure compared to a 1M glucose solution.
* Glucose: Since it doesn't dissociate, a 1M glucose solution remains as 1M of solute particles.
3. Effect on Water Movement:
* High osmotic pressure: Solutions with higher osmotic pressure (like NaCl solutions) will draw water from solutions with lower osmotic pressure (like pure water or dilute glucose solutions) across a semipermeable membrane.
* Low osmotic pressure: Solutions with lower osmotic pressure will lose water to solutions with higher osmotic pressure.
In summary:
* NaCl: Dissolves into two particles per molecule, creating a higher osmotic pressure and stronger water-drawing effect.
* Glucose: Remains as one particle per molecule, resulting in lower osmotic pressure and a weaker water-drawing effect.
Practical Example:
If you place a red blood cell in a 1M NaCl solution, the high osmotic pressure outside the cell will cause water to rush out of the cell, leading to crenation (shrinking). In contrast, a red blood cell in a 1M glucose solution will experience less water loss due to the lower osmotic pressure of the glucose solution.
