Many students open to Chapter 1, see a wall of text about "systems and surroundings," and immediately feel overwhelmed. But here is the secret: You don't read it like a thriller; you mine it for gems.
The zeroth law of thermodynamics, also known as the "law of thermal equilibrium," states that if two systems are in thermal equilibrium with a third system, then they are also in thermal equilibrium with each other. This law allows us to define a temperature scale, which is a measure of the thermal energy of a system. fundamentals of thermodynamics sonntag
The appendix tables in Sonntag (covering Water, Refrigerants, Ammonia, Ideal Gases) are crafted specifically to force interpolation skills. You rarely find a "nice" number; you must learn linear interpolation in the superheat tables. Many students open to Chapter 1, see a
PV = nRT