When is the enthalpy value 0 (response is score)
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This post was last edited by caoguanggui on 2009-7-7 15:05. Under what circumstances is the enthalpy value of a substance set to 0? That is, which reference point is generally used to specify the enthalpy value? For example, the entropy enthalpy diagram and the pressure enthalpy diagram are above.
From the definition of enthalpy, I think there is no substance with zero enthalpy. H=U+PV, U is the internal energy, which includes the translational kinetic energy, rotational energy, vibrational energy, electron binding energy, atomic nuclear energy, and the potential energy of intermolecular interactions of the molecules in the system. The internal energy cannot be zero, so the enthalpy cannot be zero. Unless everything stops moving, maybe it will be zero.
It is generally not specified in which state the enthalpy value is 0.
Hey, the enthalpy of matter is zero? No, I have heard that the enthalpy of a single substance is set to relative zero.
4# yanwenzh1204 The reference point is what you call the relative zero point. Can you tell me what the situation is? ? ? Don't fool me
Enthalpy is a state function of a thermodynamic system, represented by H. It is defined as the sum of the internal energy U of the system and the product of the pressure P and the volume V of the system, that is, H=U+PV
This post was last edited by yanwenzh1204 on 2009-7-7 19:21 Hey, this is how I understand it. I have not learned thermodynamics well. I didn't lie to you, and I don't have the ability. What we generally require is the enthalpy change, so we just set the initial state enthalpy value to zero! Enthalpy is just a state function and its value is meaningless. Any point can be taken as zero. The specific value is only the difference in enthalpy, that is, the enthalpy change. In addition, I checked and found that the liquid at -129°C is usually taken as the base point of substances H and S. The original poster is so hot on your heels, what are you trying to do?
Theoretically, the enthalpy of absolute zero is zero, which is 0K
Absolute Zero Absolute Zero represents the temperature at which all molecules and atoms that make up matter cease to move. The so-called motion refers to all spatial, mechanical, molecular and vibrational motions. Also included are some forms of electronic movement. At absolute zero, the motion of atoms stops completely, and theoretically, the volume of a gas should be zero.
At absolute zero, the movement of all particles will stop. At this time, the enthalpy is zero. Because it is impossible for nature to reach absolute zero, there is no state of zero enthalpy in nature. Zero enthalpy is an ideal state.