In a zeotropic blend, all refrigerants have the same boiling point.

• A. True
• B. It depends on the pressure
• C. Only at certain temperatures
• D. False

Answer: (D)

Zeotropic blends are made from components with different boiling points, so there isn’t a single boiling temperature for the mixture at a given pressure. As the blend boils, the lower-boiling components vaporize first, changing the liquid’s composition and causing the boiling temperature to shift along the process — this is called a temperature glide. This is what differentiates zeotropic blends from azeotropic ones, which boil at a constant temperature like a pure refrigerant. So the statement that all refrigerants in a zeotropic blend have the same boiling point isn’t correct; the blend boils over a range of temperatures rather than at one fixed point.