Gibbs free energy quiz for AP Chemistry: 10 questions with answers

by aicko
28 October 202628 October 2026

Quick answer: Entropy S measures the dispersal of energy and matter, and the Gibbs free energy change ΔG = ΔH − TΔS predicts spontaneity: a reaction is spontaneous when ΔG is negative. This AP Chemistry quiz checks Gibbs free energy with 10 multiple-choice questions and instant feedback; every answer comes with a short explanation.

Gibbs free energy quiz for AP Chemistry: 10 questions with answers

This Gibbs free energy quiz for AP Chemistry has quick multiple-choice questions with instant feedback. Need a refresher first? Read the lesson or do the worksheet on Gibbs free energy.

Ten multiple-choice questions on entropy, Gibbs energy and equilibrium. Choose one answer for each and read the explanation after every question.

Level: AP Chemistry · Curriculum: AP Chem Unit 9

Contents

Gibbs free energy quiz: the questions

What is the unit of standard molar entropy?

Which change has a positive ΔS?

What are the signs of ΔH and ΔS for a reaction spontaneous at all temperatures?

A reaction has ΔH = +30 kJ and ΔS = +100 J/K. At what temperature does ΔG = 0?

What does a negative ΔG mean?

Which relationship is correct?

If K is much greater than 1, what is true of ΔG°?

What is ΔG at equilibrium?

Which substance has the largest S° at 298 K?

A student uses ΔH = −90 kJ and ΔS = −200 J/K directly in ΔG = ΔH − TΔS with T = 298 K. What is the mistake?

Gibbs equation? — ΔG = ΔH − TΔS

Spontaneous means what for ΔG? — ΔG is negative

ΔG° and K? — ΔG° = −RT ln K

Value of R? — 8.314 J/(mol·K)

ΔG away from standard? — ΔG = ΔG° + RT ln Q

Unit of entropy? — J/(mol·K)

Crossover temperature? — T = ΔH/ΔS

ΔH negative, ΔS positive? — Spontaneous at all temperatures

ΔG at equilibrium? — Zero

Gas to liquid: sign of ΔS? — Negative

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