Solutions with the same osmotic pressure: What is the standard term for solutions that exhibit equal osmotic pressure at the same temperature?
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ADilute
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BIdeal
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CIsotonic
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DSaturated
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ESupersaturated
Answer
Correct Answer: Isotonic
Explanation
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:
Identify equal π → no net solvent flow across the membrane.Hence, tonicity is matched → solutions are isotonic.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