Solutions with the same osmotic pressure:\nWhat is the standard term for solutions that exhibit equal osmotic pressure at the same temperature?

Introduction / Context:
Osmosis drives solvent across semipermeable membranes from low to high solute chemical potential. In bioprocessing and medicine, matching osmotic pressures prevents cell lysis or plasmolysis; such solutions are called isotonic.

Given Data / Assumptions:

• Comparison at the same temperature through a semipermeable membrane.
• Solute does not cross the membrane; solvent can.

Concept / Approach:
Osmotic pressure π for dilute solutions is given by π = i * C * R * T (van’t Hoff relation), where i is the dissociation factor. Two solutions with equal π at the same T are isotonic.

Step-by-Step Reasoning:

Verification / Alternative check:
In intravenous therapy, 0.9% saline is roughly isotonic with blood plasma, demonstrating the concept practically.

Why Other Options Are Wrong:

• Dilute/ideal/saturated/supersaturated describe concentration, nonideality, or phase equilibrium, not equality of osmotic pressure.

Common Pitfalls:
Confusing isotonic with isosmotic (equal osmolarity but different membrane permeabilities can change effective tonicity).

Final Answer:
Isotonic