Why do spirits mixed with water form a milky preparation?

Study for the Pharmaceutics II Exam 2 Concepts Test with flashcards and multiple choice questions. Each question has hints and explanations. Prepare effectively for your exam!

Multiple Choice

Why do spirits mixed with water form a milky preparation?

Explanation:
When you mix spirits with water, you’re changing the solvent composition. The volatile constituents are soluble in ethanol, but they’re not fully soluble in the water-rich mixture that results from dilution. As the water content increases and the ethanol fraction drops, those oil-like components can no longer stay dissolved and they separate out as tiny droplets in the water. Light scattering by these droplets makes the mixture look milky or cloudy, similar to an oil-in-water emulsion. It’s not about a microemulsion forming, and it isn’t because water dissolves all components equally or because the spirits evaporate quickly.

When you mix spirits with water, you’re changing the solvent composition. The volatile constituents are soluble in ethanol, but they’re not fully soluble in the water-rich mixture that results from dilution. As the water content increases and the ethanol fraction drops, those oil-like components can no longer stay dissolved and they separate out as tiny droplets in the water. Light scattering by these droplets makes the mixture look milky or cloudy, similar to an oil-in-water emulsion. It’s not about a microemulsion forming, and it isn’t because water dissolves all components equally or because the spirits evaporate quickly.

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