Place the following substances in order of decreasing vapor pressure at a given temperature. PF₅ BrF₃ CF₄ A) BrF₃ PF₅ CF₄ B) BrF₃ CF₄ PF₅ C) PF₅ BrF₃ CF₄ D) CF₄ BrF₃ PF₅ E) CF₄ PF₅ BrF₃

Question

Place the following substances in order of decreasing vapor pressure at a given temperature. PF₅ BrF₃ CF₄ A) BrF₃ > PF₅ > CF₄ B) BrF₃ > CF₄ > PF₅ C) PF₅ > BrF₃ > CF₄ D) CF₄ > BrF₃ > PF₅ E) CF₄ > PF₅ > BrF₃

Quizplus · Accepted Answer

Vapor pressure decreases with increasing molecular weight due to stronger intermolecular forces. Among PFS3 (molecular weight ~ 89 g/mol), BrF3 (~137 g/mol), and CF4 (~88 g/mol), CF4 has the lowest molecular weight but similar to PFS3, and BrF3 has the highest, leading to CF4 having the highest vapor pressure and BrF3 the lowest.

Place the Following Substances in Order of Decreasing Vapor Pressure