3.1.8.2 Gibbs Free-energy Change, /\G, and Entropy Change, /\S Flashcards

1
Q

What is Gibbs free energy?

A

It tells you the energy available for work

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2
Q

What is the equation for Gibbs free energy change?

A
∆G = ∆H - T∆S
∆G = Gibbs free energy change
∆H = enthalpy change
T = temperature
∆S = entropy change
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3
Q

At what ∆G value does a reaction just become feasible?

A

Zero

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4
Q

Does entropy change with temperature?

A

Yes

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5
Q

What do all systems tend to go towards?

A

The lowest potential energy

A disordered random arrangement

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6
Q

Define feasible

A

The ability of a reaction to occur

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7
Q

Put the states of matter in order of low entropy to high entropy

A

Solid < Liquid < Gas

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8
Q

What does a lower entropy signify?

A

A more ordered substance, such as solids

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9
Q

How does an increased number of moles affect the entropy of a reaction?

A

It increases it

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10
Q

What occurs in an endothermic reaction and how does this affect the disorder?

A

The system gains energy

If the disorder introduced to a system is great enough, an endothermic reaction will be feasible

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11
Q

What is an indicator of how disordered a system is?

A

Systems can be given a number based on how disordered they are
The higher the number the higher the disorder

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12
Q

Does the entropy change of a reaction show an indication about rate?

A

No

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13
Q

What does a positive Gibbs value represent?

A

It means that it is not feasible

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14
Q

What does a negative Gibbs value represent?

A

It means that it is feasible

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15
Q

Define spontaneous

A

Same as feasible

The tendency for a reaction to happen

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16
Q

Define entropy

A

The randomness of a system
Expressed mathematically
Given the symbol, S

17
Q

What causes a positive value of ∆S?

A

A reaction where the products are more disordered than the reactants

18
Q

How do you work out the entropy change for a reaction?

A

Add all of the entropies of the products and subtract all the entropies of the reactants