Skip to content
Login Register

#state variables

2 public questions tagged with this topic.

Heat Transfer Work Distinction and Internal Energy Change

Which variable is classified as an extensive thermodynamic state variable?

**Heat and work distinction** heat is energy transfer due to temperature difference, random molecular motion, work is organized energy transfer due to macroscopic force, e.g., piston movement, both path functions depend on process, not state, internal energy U state function depends only on state (T for ideal gas), ΔU path independent, Q and W path dependent but Q-W = ΔU path independent. Extensive variables depend on the size or amount of the system and scale with it (e.g., halve when the system is halved). Volume ( V ) is extensive, while pressure ( P ) and temperature ( T ) are intensive, not dependent on

Ref: NCERT > Physics Book > Thermodynamics > Heat Transfer Work Distinction and Internal Energy Change

View Details
Specific Heat Capacity and Latent Heat

Which of the following is NOT a state variable in thermodynamics?

**Specific heat capacity** c = Q/(m ΔT) (J/kg·K), molar C = Q/(n ΔT), heat required to raise temperature, Q = m c ΔT, for water c=4186 J/kg·K, latent heat L = Q/m for phase change at constant temperature, fusion L_f and vaporization L_v, Q = m L, e.g., ice melting L_f=3.34×10⁵ J/kg, water vaporization 2.26×10⁶ J/kg. State variables depend only on the current state of the system, not the path taken to reach it. Pressure, volume, and temperature are state variables. Heat ( Δ Q ) is not a state variable; it is a mode of energy transfer dependent on the process. Using first law

Ref: NCERT > Physics Book > Thermodynamics > Specific Heat Capacity and Latent Heat

View Details