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Thermodynamics — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistryThermodynamics3 Marks
Question
  1. Classify the following processes as reversible or irreversible:
  1. Dissolution of sodium chloride.
  2. Evaporation of water at 373K and 1atm pressure.
  3. Mixing of two gases by diffusion.
  4. Melting of ice without rise in temperature.
  1. When an ideal gas expands in vacuum, there is neither absorption nor evolution of heat. Why?
✓

Answer

  1.  
  1. Reversible.
  2. Irreversible.
  3. Irreversible.
  4. Reversible.
  1. It is because no work is done.
i.e., w = 0

$\because\text{w}=-\text{P}_\text{ext}\times\Delta\text{V}=0\times\Delta\text{V}=0$

$\Delta\text{U}=\text{q}+\text{w}$

q = 0 because gas chamber is insulated

$\therefore\Delta\text{U}=0+0=0$​​​​​​​

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