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Entropy 

In thermodynamics, entropy (usual symbol S) is a measure of the number of specific ways in which a thermodynamic system may be arranged, commonly understood as a measure of disorder.

 

ENTROPY is a MEASUREMENT of DISORDER!!! AHHHHHH

Symbol For Entropy

ΔS

Entropy (2)

 

The distruibution of available energy is refered to as Entropy. The measurement of a disorder of a system is also referred to as Entropy. Nature often sees systems increasing in Entropy.

Entropy in nature example

 

When a bicycle is left outside for a prolonged period of time, it gradually becomes dirty and also rusts. Rust refers to the coating of iron oxide which is formed on either steel or iron due to oxidation.

 

The rusting signifies that the molecules within the iron are becoming less ordered; they are moving apart from each other and as a result the bicycle is breaking down. Nature is acting on the bicycle, the entropy is increasing and it is being broken down. (fig A & B)

 

Figure A and B

Figure A Bike no rust

Figure A Bike with rust

An increase in Entropy could result from...

 

1) Mixing different types of particles

for example; dissolution of sugar in water

 

2) State Change when distance between particles is increased, for example liquid water ----> steam

 

3) Number of Particles being increased

for example;

 

2H20(l) ----> 2H20 (l) + 02 (g)

REMEMBER

The biggest rise in disorder is often discovered when number of particles in gaseous state increase

Entropy Change

ΔS

Change in disorder of a system is known as ΔS, entropy change. More disordered a system becomes, ΔS will become more positive. More ordered systems will have negative ΔS values.

Example Equation

NH3 + HCL (g) ----> NH4Cl(s) ΔS = -284 J K-1 mol-1

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