Of state. Contents and Concepts 1. Comparison of Gases, Liquids, and Solids Changes of State

Problem Strategy If you let P₁ be 400 mmHg, then T₁ is 291 K (18°C), P2 is 760 mmHg, and T₂ is 308 K (35°C). You substitute these values into the Clausius–Clapeyron

equation.

11 States of Matter; Liquids and Solids
Solution

Therefore,

Answer Check Whenever you are dealing with calculated quantities of heat, always make sure that the sign of your answer makes sense. In this case, because vaporization is a process that requires energy, the answer should always be a positive quantity as it is here. Also, enthalpies of vaporization generally fall in the range of tens of kilojoules, so anything much outside that range should be suspect.

Exercise 11.3 Selenium tetrafluoride, SeF₄, is a colorless liquid. It has a vapor pressure of 757 mmHg at 105°C and 522 mmHg at 95°C. What is the heat of vaporization of selenium tetrafluoride?

See Problems 11.51 and 11.52.