Which of the following is a unique property of an azeotropic refrigerant mixture?

• A. It has a variable boiling point depending on the pressure.
• B. It reacts chemically with water to form a new compound.
• C. It separates into its individual components upon boiling.
• D. It behaves as a single substance and does not change composition when boiled or condensed.

Answer: (D)

Verified step by step guidance

1. Understand what an azeotropic mixture is: it is a mixture of two or more liquids that boils at a constant temperature and with a fixed composition, behaving like a single pure substance during phase changes.
2. Recall that unlike ideal mixtures, azeotropes do not separate into individual components upon boiling; instead, the vapor has the same composition as the liquid.
3. Recognize that the boiling point of an azeotropic mixture is constant at a given pressure, so it does not vary with composition during boiling.
4. Note that azeotropic mixtures do not chemically react with water or other components; their unique property is related to their phase behavior, not chemical reactions.
5. Conclude that the unique property of an azeotropic refrigerant mixture is that it behaves as a single substance and does not change composition when boiled or condensed.