Thermodynamics

Chemistry · Class 11

Simulation · Chemistry · Class 11

When does a reaction go on its own?

"When does a reaction go on its own?" is a free, interactive Class 11 Chemistry simulation for NEET and JEE, built on the lesson "Gibbs energy and spontaneity" in Thermodynamics. ΔH (heat given out or taken in) and ΔS (spread of energy and matter). The graph draws ΔG = ΔH − TΔS; wherever it dips below zero, shaded green, the change is spontaneous. Ice melting: ΔH = +6.00 kJ/mol, ΔS = +22.0 J/(K mol), so T = 6000/22.0 ≈ 273 K. Above 0 °C ice melts on its own, below it water freezes, and at exactly 273 K ΔG = 0: ice and water sit at equilibrium. JEE Main asked 51 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).

From the lesson Gibbs energy and spontaneity in Thermodynamics. Change the values and watch what happens.

When does a reaction go on its own?Chemistry · Class 11

In JEE Main

42 shifts analysed

51 questions from Thermodynamics across the 42 JEE Main shifts Lumi has analysed (2017–2026).

The idea behind it

NCERT § "Gibbs Energy and Spontaneity"

  • Gibbs energy is defined as G = H − TS; at constant temperature ΔG = ΔH − TΔS.
  • At constant temperature and pressure, ΔG < 0 means spontaneous, ΔG > 0 means non-spontaneous (the reverse is spontaneous), and ΔG = 0 means equilibrium.
  • ΔH < 0 and ΔS > 0: ΔG is negative at all temperatures, always spontaneous.
  • ΔH > 0 and ΔS < 0: ΔG is positive at all temperatures, never spontaneous.
  • ΔH < 0 and ΔS < 0: spontaneous only at low temperature, when |ΔH| > |TΔS|.
  • ΔH > 0 and ΔS > 0: spontaneous only at high temperature, when TΔS > ΔH.
  • The temperature at which ΔG changes sign is T = ΔH/ΔS, assuming both stay roughly constant; convert ΔS to kJ K⁻¹ mol⁻¹ before dividing into ΔH in kJ mol⁻¹.

Questions

3 answers

What does the "When does a reaction go on its own?" simulation show?
ΔH (heat given out or taken in) and ΔS (spread of energy and matter). The graph draws ΔG = ΔH − TΔS; wherever it dips below zero, shaded green, the change is spontaneous.
Does JEE Main ask questions from Thermodynamics?
Yes. JEE Main asked 51 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
Is this simulation free?
Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Gibbs energy and spontaneity" in Thermodynamics (Class 11 Chemistry).

Embed this simulation

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