Thermodynamics

Tested in 2 real MPSC questions across 2 years (2020–2023). See it in context on the interactive Concept Graph →

Years it was asked

2023 2020

What mastering this unlocks

Free energy in photochemistry

Real questions that test this

जर 1.0 मोल आदर्श वायूचे आकारमान मानक तापमान आणि दाबाला 22.4 Lit असेल तर सर्वकष वायु स्थिरांक, R ______ असतो. If one mole of an ideal gas occupies 22.4 Lit at Standard Temperature and Pressure, then the value of the universal gas constant R is

a)0.0821 atm Lit mol-1 K-1&check; Correct

b)8.314 x 10⁷ Joules K-1 mol-1

c)82.1 atm Lit mol-1 K-1

d)8.314 erg K-1 mol-1

The universal gas constant R has standard values: 0.0821 atm L mol-1 K-1 or 8.314 J K-1 mol-1 (which is 8.314 x 10⁷ erg K-1 mol-1). Option (a) gives R in L atm units, while option (b) gives it in Joules which is 8.314 J, but the exponent 10⁷ makes it ergs. Wait, 8.314 J = 8.314 x 10⁷ ergs. Let's check standard values.

रासायनिक घटाचे विद्युतगामक बल धन असते, जेव्हा अभिक्रियेचा मुक्त ऊर्जा बदल हा असतो. The EMF of a chemical cell is positive, when the free energy change of the reaction is .

1)> 0

2)< 0&check; Correct

3)= 0

4)मुक्त ऊर्जा बदल आणि विद्युतगामक बलाचा संबंध नाही / No relationship between the free energy change and EMF

The relationship between cell emf (E) and Gibbs free energy change (delta G) is given by delta G = -nFE. For the EMF to be positive (>0), the free energy change must be negative (<0) for a spontaneous process.

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