1 Thermodynamic Systems, Properties, and States Free Online FlashCards

What are a thermodynamic system and its boundary?

A thermodynamic system is the quantity of matter or region in space selected for study; its boundary separates it from its surroundings.

What can cross the boundary of a closed system?

A closed system contains a fixed amount of matter, so matter cannot cross its boundary. Energy may still cross.

What defines an open system?

An open system allows both matter and energy to cross its boundary. Its chosen region is often called a control volume.

What distinguishes an isolated system?

An isolated system exchanges neither matter nor energy with its surroundings. It is an idealization that a well-insulated, sealed container can approximate.

What is an intensive property?

An intensive property is independent of system size. Temperature, pressure, and density are examples.

What is an extensive property?

An extensive property depends on system size and is additive for combined subsystems. Mass, volume, and total internal energy are examples.

How is a specific property defined?

A specific property is an extensive property divided by mass. Specific volume and specific internal energy are examples, and specific properties are intensive.

Why is a property called a state property?

A property is a measurable macroscopic characteristic that depends on the system’s present condition, not on how that condition was reached.

What specifies the state of a system?

A system’s state is its condition described by a sufficient set of independent properties. For a simple, compressible substance of fixed composition, independent pressure and temperature often suffice.

What does an equation of state express?

An equation of state relates properties. For an ideal gas, one example is $pV=mRT$.

What does thermodynamic equilibrium mean?

Thermodynamic equilibrium means there is no tendency for spontaneous change in the system’s macroscopic state; no unbalanced driving forces are causing change.

What is thermal equilibrium?

Thermal equilibrium means there are no temperature differences driving heat transfer.