Which colligative property measurement is most suitable for determining the high molecular weight of synthetic polymers and proteins?
Answer and explanation
Correct answer: D. Osmotic pressure
- Step 1: Large macromolecules yield very low molar concentrations even at high mass concentrations. Step 2. Freezing point and boiling point changes are negligible (< 0.001 °C) and difficult to measure accurately. Step 3. However, osmotic pressure Pi = MRT produces measurable liquid column heights (several centimeters of water) even at millimolar concentrations. Answer: Osmotic pressure. Why not the others: Other colligative effects produce imperceptible changes for large molar masses.
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