Chemistry I / Gibbs Free Energy and Spontaneity
Practice question · Fill in the blanks

Complete the account of what Gibbs free energy does and does not tell you.

A ______ value of ΔG\Delta G means the reaction is spontaneous, a value of exactly zero means the system is at ______, and the magnitude tells you nothing about the reaction ______, which is governed instead by the ______.

Word bank: negative · equilibrium · rate · activation energy · positive

Hints
  1. The first blank is the sign that favours the forward direction.
  2. The last two blanks are about kinetics, not thermodynamics.
Show the answer

A negative value of ΔG\Delta G means the reaction is spontaneous, a value of exactly zero means the system is at equilibrium, and the magnitude tells you nothing about the reaction rate, which is governed instead by the activation energy.

Why

Negative means spontaneous, zero means equilibrium, and rate is a kinetic question answered by the activation energy. Confusing the size of ΔG\Delta G with speed is the most persistent misconception in this topic.

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