This discussion centers on calculating heat transfer in a closed system using the ideal gas law and the first law of thermodynamics. The heat transferred into the system is determined by the equation Q = ΔU + W, where ΔU for one mole of an ideal gas is given by ΔU = C_v(T_f - T_i). The confusion arises regarding the use of C_v versus C_p, with the clarification that C_v is appropriate for internal energy calculations, while C_p is relevant for enthalpy at constant pressure conditions.
PREREQUISITESStudents and professionals in physics, engineering, and thermodynamics who are interested in understanding heat transfer and energy calculations in closed systems.
Using the first law of thermodynamics, how would you answer this question?Axe199 said:So i am making a simple demonstration of ideal gas law using a cylinder piston system, heating the system so the piston is pushed up, i wanted to calculate the heat transferred into the system, will it be Cp(Tf-Ti) or Cp(Tf-Ti)+ work done by the system ?
well using the first law Q-W=ΔU, Q will equal to to ΔU+ W but i don't know how to calculate ΔUChestermiller said:Using the first law of thermodynamics, how would you answer this question?
For one mole of an ideal gas, ##\Delta U =C_v(T_f-T_i)##. Now what?abdo799 said:well using the first law Q-W=ΔU, Q will equal to to ΔU+ W but i don't know how to calculate ΔU
why use Cv not Cp the system has constant pressure and variable volumeChestermiller said:For one mole of an ideal gas, ##\Delta U =C_v(T_f-T_i)##. Now what?
The internal energy of an ideal gas is (a) a function of temperature only or (b) a function of temperature and volume (per unit mass)?abdo799 said:why use Cv not Cp the system has constant pressure and variable volume