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# WATER at 1 Atmosphere

The table presents selected thermodynamic properties of water at a pressure of One Atmosphere over the range of temperatures, -40°C to 500°C. This is the "solid-to-liquid" ~ melting phase change temperature and the "liquid-to-solid" ~ freezing temperature one atmpsphere. At 0°C, water is either solid (with solid properties) or liquid (with liquid properties). To tabulate both sets of properties at the same 0°, in the same column, temperature is awkward. Consequently we notate the solid to have the temperature 0-°C and the liquid to have the temperarure, 0+°C. Thus the temperatures, 0-°C, means "at 0°C" but solid and the temperature 0+°C means "at 0°C" but liquid. The same conventiion is used for 100°

The data of this table present states of water always at the pressure, 1 atmosphere over the temperature range, -40°C to 500°C).

 Water at One Atmosphere p(Ts(p)) -40°C 0-°C(solid~s) 0+°C(liquid~f) 100-°C(liquid-f) 100+°C(gas-g) 500°C 101.3 kPa (100°C) v ~ cm³/gu ~ J/g h ~ J/g 1.08-410-411 vs = 1.09us = -332hs = -333 vf = 1.00uf = 0.10hf = 0.10 vf = 1.04uf = 418hf = 419 vg = 1680ug = 2505hg = 2675 353431303488

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Problems below ask you to use the tabular data (water "at one atmosphere) to answer some questions regarding "state" and "events" of water occuring - at (the ambient pressure) 1 atmosphere.

1) 5000 grams of water exists at 1.0 atmosphere and 500°C. What is the volume of the water?

Solution:   V = mv(1atm, 500°C) = 5000g (3534 cm3/g) = 17.7m3

2) Three grams of liquid water and 5000 cubic centimeters of gaseous water coexist in equilibrium at one atmosphere. What is the temperature? Calculate the enthalpy, H?
♦  Phases of water that coexist at one atmosphere have the temperature, 100°C. The enthalpy is:

H = mf hf + mg hg

H = mf hf + (Vg/vg) hg

H = 3g(419 J/g) + [5000 cm3/1680 cm 3/g](2675 J/g)

H = 9218 J

3) Determine the volume of 400grams of steam at 1.0 atmosphere and a) 300°C. b) 167°C.
300°C is a nice number because it is midway between the table entries, 100+°C and 500°C. The fast answer is V = m{[v(500°C) + v(100+°C]/2}. Below we show all steps of the interpolation.  ## WATER at 1 Atmosphere

The table presents selected thermodynamic properties of water. Water at 0° can be either solid (with its properties) or liquid (with its properties). To list both sets of properties, 0° is notated as 0-°C and 0+°C. The temperatures, 0-°C, means 0°C but solid; 0+°C means 0°C but liquid.

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