## 12 Questions

What is the consequence of the second law of thermodynamics in a closed system?

Entropy increases over time

What is the condition for a reaction to be spontaneous at all temperatures?

∆H must be negative and ∆S must be positive

Which of the following is a violation of the second law of thermodynamics?

A room spontaneously organizing itself into a perfectly clean state

What is the relationship between the spontaneity of a process and the value of ∆G?

∆G < 0 indicates a spontaneous process

What is the significance of ∆G = 0 in a reaction process?

The reaction is at equilibrium

What is the unit of Gibbs free energy?

Joules (J)

Which of the following factors does not affect the spontaneity of a reaction according to Gibbs free energy?

Concentration of reactants

What is the scenario in which entropy remains unchanged?

Arranging books in a shelf by height

What is the equation that correctly represents the relationship between Gibbs free energy, enthalpy, and entropy?

∆G = ∆H - T∆S

What is the significance of a negative ∆G value?

The reaction is spontaneous

What is the relationship between the equilibrium constant (K) and the spontaneity of a process?

If K > 1, the process is spontaneous

What is the effect of an endothermic process on the enthalpy change (∆H)?

∆H increases

## Study Notes

### Second Law of Thermodynamics

- States that entropy of the universe increases in spontaneous processes and remains unchanged in equilibrium processes
- Entropy represents disorder or randomness in a system
- In energy transfer or transformation, some energy becomes lost as heat
- Heat always flows from a hot object to a cold object
- Irreversibility of natural processes is a principle of increasing entropy

### Entropy

- Measure of disorder or randomness in a system
- Increases over time in a closed system

### Predicting Spontaneity

- Gibbs free energy (∆G) is used to predict spontaneity of a process
- ∆G < 0 indicates a spontaneous process at constant temperature and pressure
- ∆G = 0 indicates equilibrium
- K > 1 indicates a spontaneous process

### Types of Processes

- Rusting of iron is a spontaneous process
- Melting of ice cubes at -50°C and 1 atm is non-spontaneous
- Arranging books on a shelf by height does not show increasing entropy
- Endothermic process absorbs heat from the surroundings
- Ice formation is an example of a non-spontaneous process

### Gibbs Free Energy

- ∆G = ∆H – T∆S is the equation correctly representing the relationship between Gibbs free energy, enthalpy, and entropy
- ∆G is typically measured in Joules (J)
- Negative ∆G indicates a spontaneous reaction
- Factors affecting spontaneity of a reaction: temperature (T), enthalpy change (∆H), and entropy change (∆S)

Test your understanding of Gibbs free energy and its relationship with enthalpy, entropy, and reaction direction. This quiz covers the significance of ΔG = 0 in a reaction process and the conditions for a spontaneous reaction.

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