Gibbs free-energy change ΔG

Last updated: 10/02/2020

WJEC A-Level Chemistry Unit 3.7 – Entropy and feasibility of reactions Gibbs free-energy change ΔG

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Question 1 of 20

1. Question
Which chemist discovered the idea of ‘free energy’?
- Josiah Willard Gibbs
- Humphrey Davy
- Joseph Priestley
- Justus Lieburg
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Question 2 of 20

2. Question
What is the definition of free energy change?
- The balance between enthalpy, entropy and temperature
- The balance between energy, enthalpy and temperature
- The balance between entropy, energy and temperature
- The balance between energy, enthalpy and entropy
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Question 3 of 20

3. Question
What is the symbol for free energy?
- G
- F
- E
- FE
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Question 4 of 20

4. Question
What is the symbol for free energy change?
- ΔG
- ΔF
- ΔE
- ΔT
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Question 5 of 20

5. Question
What is the Gibbs’ equation?
- ΔG = ΔH – TΔS
- ΔG = TΔS – ΔH
- ΔG = ΔH x TΔS
- ΔG = TΔS + ΔH
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Question 6 of 20

6. Question
How can we calculate the total entropy change?
- Sum of entropy in the system – sum of entropy in the surroundings
- Sum of entropy in the system x sum of entropy in the surroundings
- Sum of entropy in the surroundings + sum of entropy in the system
- Sum of entropy in the surroundings – sum of entropy in the system
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Question 7 of 20

7. Question
What does the ΔG stand for in the Gibbs’ Equation?
- Free energy change
- Enthalpy change
- Temperature + entropy change
- Temperature x entropy change
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Question 8 of 20

8. Question
What does the ΔH stand for in the Gibbs’ Equation?
- Enthalpy change
- Free energy change
- Temperature + entropy change
- Temperature x entropy change
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Question 9 of 20

9. Question
What does the TΔS stand for in the Gibbs’ Equation?
- Temperature x entropy change
- Free energy change
- Temperature + entropy change
- Enthalpy change
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Question 10 of 20

10. Question
For a reaction to happen simultaneously, what must the entropy do?
- Increase
- Decrease
- Remain the same
- Stop
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Question 11 of 20

11. Question
Describe how spontaneous endothermic reactions are.
- Only spontaneous with a positive entropy and high temperature
- Generally spontaneous, due to negative change in enthalpy
- Generally spontaneous, due to positive change in enthalpy
- Only spontaneous with a negative entropy and low temperature
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Question 12 of 20

12. Question
Describe how spontaneous exothermic reactions are.
- Generally spontaneous, due to negative change in enthalpy
- Only spontaneous with a positive entropy and high temperature
- Generally spontaneous, due to positive change in enthalpy
- Only spontaneous with a negative entropy and low temperature
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Question 13 of 20

13. Question
Which of these factors will impact whether or not a reaction proceeds spontaneously?
- The activation energy
- The molecules
- The energy change
- Whether the reaction is exothermic or endothermic
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Question 14 of 20

14. Question
Which of these factors will impact whether or not a reaction proceeds spontaneously?
- The rate of reaction
- The size of particles
- The forces between molecules
- The disorder of the reaction
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Question 15 of 20

15. Question
What is needed for a spontaneous change to occur?
- Total entropy change to be positive
- Total energy change to be positive
- Total entropy change to be negative
- Total energy change to be negative
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Question 16 of 20

16. Question
What is needed for a spontaneous change to occur?
- Free energy change to be negative
- Enthalpy change to be negative
- Free energy change to be positive
- Enthalpy change to be positive
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Question 17 of 20

17. Question
Describe the feasibility of a spontaneous change when ΔG is negative, ΔS is positive and ΔH is negative.
- Reaction is feasible
- Reaction is not feasible
- Reaction is feasible at low temperatures
- Reaction is feasible at high temperatures
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Question 18 of 20

18. Question
Describe the feasibility of a spontaneous change when ΔG is positive, ΔS is negative and ΔH is positive.
- Reaction is not feasible
- Reaction is feasible
- Reaction is feasible at low temperatures
- Reaction is feasible at high temperatures
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Question 19 of 20

19. Question
Describe the feasibility of a spontaneous change when ΔG is negative at low temperatures, ΔS is negative and ΔH is negative.
- Reaction is feasible at low pressures
- Reaction is not feasible
- Reaction is feasible
- Reaction is feasible at high pressures
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Question 20 of 20

20. Question
Describe the feasibility of a spontaneous change when ΔG is negative at high temperatures, ΔS is positive and ΔH is positive.
- Reaction is feasible at high pressures
- Reaction is feasible at low pressures
- Reaction is not feasible
- Reaction is feasible
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