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Maharashtra State BoardHSC Science (Electronics) 12th Standard Board Exam
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MCQ ऑनलाइन अभ्यास परीक्षा६०
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अवधारणा स्पष्टीकरण और वीडियो५९६
समय सारणी३३
पाठ्यक्रम

Spontaneous (Irreversible) Process

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Estimated time: 5 minutes
Maharashtra State Board: Class 12

Key Points: Spontaneous (Irreversible) Process

  • Spontaneous processes are those that occur naturally without any external force. They proceed in one direction and cannot be reversed unless an external influence is applied.
  • Entropy is a measure of disorder or randomness in a system. Greater disorder means higher entropy.
  • Entropy and spontaneity: In a spontaneous process, the entropy of the system tends to increase.
Maharashtra State Board: Class 12

Law: Second Law of Thermodynamics

The entropy of the universe keeps increasing and tends to reach a maximum.

Total entropy change:
ΔSuniverse = ΔSsystem + ΔSsurroundings > 0

  • ΔStotal > 0 → Process is spontaneous
  • ΔStotal < 0 → Process is non-spontaneous
  • ΔStotal = 0 → System is at equilibrium
Maharashtra State Board: Class 12

Definition: Gibbs Free Energy

The maximum amount of energy available to a system during a process that can be converted into useful work is called the Gibbs free energy. 

It is given as, ΔG = ΔH – TΔS

where,

  • ΔG = change in Gibbs energy
  • ΔH = change in enthalpy
  • ΔS = change in entroру.

Related QuestionsVIEW ALL [25]

The criterion for a spontaneous process is ______.

For a certain reaction ΔH0 is −224 kJ and ΔS0 is −153 J K−1. At what temperature the change over from spontaneous to non-spontaneous will occur?

Answer the following question.

Determine whether the following reaction is spontaneous under standard state conditions.

2H2O(l) + O2(g) → 2H2O2(l)

if ΔH° = 196 kJ, ΔS° = –126 J/K, does it have a cross-over temperature?

Identify whether the following pair have a larger entropy or not. If yes then Why?

C2H5OH(l) or C2H5OH(g)

Calculate ΔG0 for the reaction

\[\ce{CH_{4(g)} + H_{2(g)}-> C2H_{6(g)}}\]

State whether the reaction is spontaneous or not. (Given: KP = 3.358 × 1017, T = 25° C, R = 8.314 × 10−3 kJK−1 moI−1)

Identify whether the following pair have a larger entropy or not. If yes then Why?

O2{g) at 1 atm or O2(g) at 10 atm both at the same temperature.

Identify whether the following pair have larger entropy or not. If yes then Why?

He(g) in a volume of 1 L or He(g) in a volume of 5 L both at 25°C.

Relation between ΔH and ΔU for the reaction, \[\ce{2SO_{3(g)} -> 2SO_{2(g)} + O_{2(g)}}\] is _______.

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