CHAPTER 2 Properties of Pure Substances

Pure Substances Fixed chemical composition –N2–N2 –Air If mixed phases, –N2–N2 –Not Air

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2-1 FIGURE 2-11 T-v diagram for the heating process of water at constant pressure. Saturated liquid Saturated Vapor Saturation Temperature, T sat, at 1 atm pressure. Fixed at a fixed pressure for a pure substance Saturation pressure,P sat, for 100°C

Latent heats and Phase Changes Latent heat of fusion (melting) Latent heat of vaporization (boiling) Magnitudes depend on temp. or press. Temp control by a boiling substance –Refrigerant-134a °C –Liquid nitrogen °C Vacuum cooling of vegetables –Quick but more expensive

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2-2 FIGURE 2-16 T-v diagram of constant- pressure phase-change processes of a pure substance at various pressures (numerical values are for water).

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2-3 FIGURE 2-18 T-v diagram of a pure substance.

FIGURE 2-19 P-v diagram of a pure substance. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2-4

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2-5 FIGURE 2-21 P-v diagram of a substance that contracts on freezing.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2-6 FIGURE 2-22 P-v diagram of a substance that expands on freezing (such as water).

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2-7 FIGURE 2-25 P-T diagram of pure substances.

FIGURE 2-26 P-v-T surface of a substance that contracts on freezing. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2-8

FIGURE 2-27 P-v-T surface of a substance that expands on freezing (like water). Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2-9

Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 2 Module 2 Slide 13 Additional Aspects for the P-V-T Surface for Water Enthalpy...

Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 2 Module 2 Slide 14 Additional Aspects for the P-V-T Surface for Water Enthalpy defined