Entropy Key Points and Definitions

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Entropy, S is
The quantitative measure of disorder in a system
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All substances posess some degree of disorder because particles are in constant motion, thus
S is always a positive number
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Entropy increases during the changes in state that give more randomness, for example
solid (low entropy --> gas (high entropy)
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The more disorder there is in the system, the
Higher the entropy
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Entropy ______ when a solid lattice dissolves
Increases
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In a reaction where there is an increase in the number of gaseous molecules, entropy
Increases
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The standard entropy S, of a substance is
The entropy content of one mole of the substance under standard conditions
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The standard entropy change of a reaction can be calculated using the standard entropies of the reactants and products:
ΔSºreaction = ΣSº(products) - ΣSº(reactants)
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If a change makes a system more random ΔH is positive, and if a change makes a system more ordered, ΔS is
Negative
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Standard entropy change of reaction, ΔSº, is
The entropy change that accompanies a reaction in the molar quantities as expressed in a chemical equation under standard conditions, all in standard states
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The free energy change ΔG is
The balance between enthalpy, entropy, and temperature for a process: ΔG = ΔH - TΔS
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For an endothermic reaction to take place spontaneously, ΔS must be positive, and the temperature must be high enough so that
TΔS>ΔH
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In calculations concerning ΔG= ΔH - TΔS 1, units must be the same for kJ/J
The units need to be the same, to convert ΔS to kJ K^-1 mol^-1 /1000
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In calculations concerning ΔG= ΔH - TΔS entropy is worked out using K
To convert C to K add 273 and the opposite to convert K to C
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Card 2

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All substances posess some degree of disorder because particles are in constant motion, thus

Back

S is always a positive number

Card 3

Front

Entropy increases during the changes in state that give more randomness, for example

Back

Preview of the front of card 3

Card 4

Front

The more disorder there is in the system, the

Back

Preview of the front of card 4

Card 5

Front

Entropy ______ when a solid lattice dissolves

Back

Preview of the front of card 5
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Comments

Lizzie Keys

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This is quite helpful but the answers are obvious when only one option makes sense. Hehe.

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