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Thermodynamics — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistryThermodynamics3 Marks
Question
  1. State first law of thermodynamics.
  2. Heat (q) and work function (w) individually are not state functions but their sum is always a state function. Why?
  3. Define extensive property with example.
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Answer

  1. First law of thermodynamics: It states energy can neither be created, nor be destroyed. It can change from one from to another. The total energy of universe remains constant.
$\Delta\text{U}=\text{q}+\text{w}$
  1. 'q' and 'w' depend upon path, therefore, these are path function.
$\text{q}+\text{w}=\Delta\text{U}$

$\Delta\text{U}$ is internal energy change which is state function because it depends upon initial and final state of the system and not on path, therefore, 'q + w' is state function.
  1. Extensive property: The property which depends upon amount of substance is called extensive property, e.g., mass, volume are extensive properties.

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