23-3 The first law of thermodynamics 1. For a thermodynamic system, internal energy is the only type of energy the system may have the law of conservation of energy of the system can be expressed as First law of thermodynamics) Q+M=△Emt (23-6) 0Q is the energy transferred (as heat) between the system and its environment because of a temperature different23-3 The first law of thermodynamics 1.For a thermodynamic system, internal energy is the only type of energy the system may have. The law of conservation of energy of the system can be expressed as (First law of thermodynamics) (23-6) (i) Q is the energy transferred (as heat) between the system and its environment because of a temperature different. Q +W = Eint