Entropy Flashcards
Entropy
Extent of disorder of energy in a system
A reaction will be spontaneous (proceed in forward reaction) at any temperature if:
It is endothermic (negative enthalpy change), and gains entropy
Entropy for solids
solids are highly ordered (extent to which substances are confined to a location)
Entropy for gases
Gases are highly disordered due to the greater dispersal of matter due to a higher random motion of the gases and thus have a very high entropy.
What happens to entropy when a solid melts?
Particles become free to move through the liquid, so entropy increases because the disorder of the system increases
Spontaneity of a reaction that is endothermic but gains entropy
Will be spontaneous if a significant gain in entropy compensates for the positive enthalpy change. A higher temperature will help.
Effect of volume on entropy
Only applicable to gases. Particles have more room to move which means there are more positions where particles can be found. If there is an increase in distribution, there is an increase in disorder.
Effect of number of particles in system on entropy
If there are more moles on one side of the equation, then there are more particles moving about and therefore more possible ways in which they can be arranged, and thus an increase in disorder.
Effect of complexity of a system on entropy
Systems with large, complex molecules have greater entropy than those with small, simple molecules
Effect of temperature on entropy
Higher temperature increases the speed of particle movement, and therefore increases the random movement of particles
Effect of aqueous state on entropy
Aqueous molecules are more disordered than pure solids or liquid states because there is an increase in the dispersal of matter / degree of disorder
If entropy of the system increases, what happens to the entropy of the surroundings?
It decreases because heat is transferred into the system from the surroundings. This results in less random motion of the particles in the surroundings.
