If you could invest two hours making your own summary, you would understand and learn much more, and you could write down a lot more thing that could be more useful for the exam. Both W and L are ways to symbolize work. That is, the Avogrado number of elementary entities. Reproduction permitted if quoting the source.
|Date Added:||26 February 2004|
|File Size:||57.53 Mb|
|Operating Systems:||Windows NT/2000/XP/2003/2003/7/8/10 MacOS 10/X|
|Price:||Free* [*Free Regsitration Required]|
Reproduction permitted if quoting the source. It is a result which is independent from the transformation. Both W and L are ways to symbolize work. In contrast, when we talk about simple bodies, for example ideal gases, the only form of internal energy that they possess is the agitation movement of their molecules: Reproduction permitted if quoting the source.
Ricardo Cabrera, CALOR Y TERMODINAMICA, gases ideales 3, ejercicios resueltos
We assume that the work performed by the gas at constant pressure is calculated as: Indeed, some bodies can store energy internally in varied ways, usually in a chemical way. Without much detail, the basic guidelines are: Reversible evolution of ideal gases An evolution of a gas between two different states different volume, different pressure and different temperature is usually represented by pressure-volume graphs like the ones below.
This helps to understand that:. In the case of an ideal gas, the internal energy depends exclusively on the temperature. On the other hand, if you want to calculate the work done by a gas between two instants, between two states or between two whatever, you need to know the "history" of the process, the succession of intermediate states through which it happened.
Translated by Esteban Djeordjian. The internal energy of an ideal gas, Uis a state function. Applying the First Law, we can know that: This helps to understand that: It is a variation between states.
Termodibamica - by the way - when there is no change in temperature, that relationship is still valid. The explanation is found in the previous paragraphs: Perhaps it might sound strange the fact that even regardless of the type of evolution an ideal gas has, the calculation of the energy variation should be made using the specific molar heat at constant volume, cvwhen, for example, Evolution occurred at constant pressure.
Well, I'll show you for isobaric evolutionas an example that the result is correct. That's why we study them.
Just don't use it! Translated by Esteban Djeordjian.
It is clear, then, that the mole was born to establish any number of entities. If you fill a balloon with a mixture of air and propane the gas used by the stoveand then you strike a match near it don't do it! Last updated on Feb This is called reversible evolution and its main property is that every gas intermediate state between any two states is completely defined its known.
Ecuación de estado y modelo molecular de un gas
What does it mean that is a state function? There are no restrictions for evolutions that occur in real life, and in most of the cases they are so chaotic that attempting a graphical representation of a real evolution could be considered utopian.
Probably the concept of "state functions" had been used without much precision in the beginning of the thermodynamics. The expression fot the heat exchanged arises from the theory of calorimetry. But inJosiah Willard Gibbsin his "paper graphical methods in liquid thermodynamics," states: I only need to apply the equation of state of ideal gases, resuelts First Law of Thermodinamics: The ejercicis that these ideal evolutions give us is valid and allows to establish precise limits to the real transformations that occur in the universe.