Question

The temperature dependence of the vapour pressure is given by the Clapeyron equation,

A) ln(P2/P1) = (ΔH/R)(1/T1 - 1/T2)
B) ln(P1/P2) = (ΔH/R)(1/T1 - 1/T2)
C) ln(T1/T2) = (ΔH/R)(1/P2 - 1/P1)
D) ln(T2/T1) = (ΔH/R)(1/P2 - 1/P1)

Answer 1

The correct form of the Clausius-Clapeyron equation, which relates a substance's vapor pressure to its temperature, is expressed as ln(P2/P1) = (ΔHvap/R)(1/T1 - 1/T2).

Step-by-step explanation:

The question pertains to the Clausius-Clapeyron equation, which is a key concept in thermodynamics within the field of Chemistry. This equation provides a quantitative relation between a substance's vapor pressure and its temperature. Specifically, the Clausius-Clapeyron equation is given by the formula:

ln(P2/P1) = (ΔHvap/R)(1/T1 - 1/T2)

where:

• ln is the natural logarithm
• P1 and P2 are the vapor pressures at temperatures T1 and T2, respectively
• ΔHvap is the heat of vaporization
• R is the universal gas constant (8.314 J/(mol·K))
• T1 and T2 are the absolute temperatures in Kelvins at which the vapor pressures P1 and P2, respectively, were measured

Thus, the correct answer to the student question is:

A) ln(P2/P1) = (ΔHvap/R)(1/T1 - 1/T2).