Thermodynamic Properties of Pure Substances: A Basic Introduction, Lecture notes of Thermodynamics

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Thermodynamic

Properties of Pure

Substances

UNIT VI

Pure Substance

 Matter is everything that has inertia

 Have a constant or uniform composition throughout.  A pure substance does not have to be a single chemical element (can be a compound) Ag, Au, Hg, Pb  Compounds- water, baking soda, salt

Thermodynamic Properties

characteristic features of a system capable of specifying the system’s state describe the thermodynamic state of fluid  have classifications and general classes

Thermodynamic Properties

Classifications: a. Measured properties b. Fundamental properties c. Derived properties General classes a. Intensive independent on the quantity of matter) b. Extensive dependent on the quantity of matter)

Thermodynamic Properties

Measured properties Properties of the system directly accessible in the laboratory Density, volume, temperature, pressure, expansion

Density and Specific Gravity

Density is the measurement of how tightly a

material is packed together

 compares the amount of matter an object has to

its volume

where m is the mass of a sample of the substance

and V its volume

 SI unit of density is kg/m 3

Specific Gravity

the ratio of the density of that substance to the density of water at

4. 0 °C  specific gravity of alcohol is 0. 79 (0.79x 3 kg/m 3 )/(1.00x 3 kg/m 3 )

Pressure

fluid exerts pressure in every direction

for a fluid at rest, the force due to fluid pressure

always acts perpendicular to any solid surface it

touches

Atmospheric Pressure

used unit of pressure atmosphere 1 atm= 1. 013 x 10 5 N/m 2 = 101. 3 kPa bar - meteorology and weather maps 1 bar= 1.000 x 5 N/m 2

Gauge Pressure

tire gauges, and most other pressure gauges, register the pressure above and beyond atmospheric pressure  to get absolute pressure, P, we must add the atmospheric pressure, to the gauge pressure, PG

P= PG +P 0

Equations of State

Equation which provide relationships

between properties

Ideal Gas Equation of State

PV=mRT