THERMO Spoken Here! ~ J. Pohl © ~ 2019 (D0050-196)

4.02 Normal Properties: WATER

The word normal means "having the pressure, one atmo­sphere." The brief sketch (a pressure-temperature projection of the surface of water) is called a "phase diagram." Phase change temperatures and regions of solid, liquid and gas and shown. l The hor­izontal dashed line (pressure = 1 atm) is the locus "normal" states of water. One format for normal properties is a list of phase change temper­atures, average specific heats for each phase and latent heats for phase changes
- Figure 1 and Table 1.

Figure 1: p-T Perspective - Normal States: WATER (@ 1 Atm)

Table 1:   Phase Boundaries/Specific and Latent Heats: WATER (@ 1 Atm)
1 (A)
Heating or Cooling
Melting or Freezing
Heating or Cooling
Boiling or Condensing
Heating or Cooling
2 T < 0-°C
(T < 32-°F)
T = 0°C
Sol and/or Liq
(T = 32°F)
0+°C < T < 100-°C
(32 < T < 212°F)
T = 100°C
Liq and/or Gas
(T = 212°F)
T > 100+°C
(T > 212°F)
3 ρsol
0.92 g/cm3

(57.2 lbm/ft3)
ρsf = ρliq - ρsol
0.08 g/cm3

(5.2 lbm/ft3)
1.00 g/cm3

(62.4 lbm/ft3)
vfg = vg - vf
1679 cm3/g

(26.8 ft3/lbm)
Ideal Gas
  pV = m(R/M)T
4 csol,avg
1.96 J/g°C

(0.45 Btu/lbm°F)
hsf = hf - hs
333 J/g

(144 B/lbm°F)
4.2 J/g°C

(1.00 Btu/lbm°F)
hfg = hg - hf
2252 J/g

(970 Btu/lbm)
cv and cp

  • Figure 1 is a perspective (not to scale) of the p-v-T surface for water. Locations along the dashed line indicate "normal states." Solid, liquid and gas regions, notated "(A), (C), and (E)" in Figure 1, have their single phase properties listed in Table 1 columns, "(A), (C), and (E)," respectively.
  • Table 1: Row 1 presents the common names of "heat event" for single phase (A, C or E) and phase change (B or D). Relavant properties are in rows 2,3, and 4.
  • Table cell (4A) and (4C) list (4)

Energy Equation:  At its basis, the energy equation recognizes energy of a system and equates its potential changes to the energy change mechanisms, work and heat. We find energy equations written in three mathematical forms: Differential, Increment, and Rate.


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