Question

a. What is the extensive property of interest/study in the first law of thermodynamics?

b. What three processes can influence the property of interest in an open system analysis of the first law of thermodynamics?

c. What crosses an open system boundary that cannot cross a closed system boundary?

d. Which are additive in nature, intensive properties or extensive properties?

e. Is the rate of change of a property inside a system boundary denoted with a dot or with a time derivative?

f. Is the rate at which a property crosses a system boundary denoted with a dot or with a time derivative?

g. What is the region of space outside of the system called?  

Answer 1

a) The First Law of Thermodynamics States that the change in internal energy (ΔU) is equal to the heat added to the system (Q) minus the work done by system (W).

ΔU =Q-W

Here, Internal Energy is an extensive property as it depends upon the mass of the system.

b) Constant Volume (Isochoric), Constant Pressure ( Isobaric) and Constant Temperature ( Isothermal) procsess are the three processes influencing the properties in an open system analysis.

c) Mass can cross an open system boundary but not a closed sytem boundary.

d) Extensive properties are additive; you can add mass, volume, internal energy. etc

e) The rate of change of property inside a system boundary is denoted by a time derivative. Like temperature change within a system.

f) The rate at which property crosses a system is denoted bya dot. Like rate of heat added to the system.

g) The region of space outside a sytstem is called Surrounding. The system and Surroundings both interact with each other.