Chemistry Ch5 Entropy Factors Flashcards
The fkin title
How will change in temperature affect ∆S
As temperature increases, the average kinetic energy of the particles and the range of energies increase
Thus causes the broadening of the Maxwell-Boltzmann energy distribution of the particles
Thus there are more way in which the energy can be distributed among the particles in the hotter system
Hence entropy increases
How will a change in phase affect ∆S
When a solid melts or sublimes, or when a liquid vaporises, the particles in the final stage move more freely and are more disordered than in the initial state.
Thus increases the number of ways that the particles and the energy can be distributed.
Explain the difference in entropy between solid and gaseous state
In a solid,
The particles vibrate about their fixed positions
The energy is thus the least dispersed and the solid has the lowest entropy
In a gas,
The particles are the most randomly arranged and are able to move freely and possess a wide range of kinetic energy
There are many ways the energy of the particles is distributed, thus it has the highest entropy.
How will change in number of particles affect ∆S
When a chemical reaction results in an increase in the number of gas particles, the number of ways the particles and the energy can be distributed increases. Hence there is an increase in entropy.
If there is no change in the number of gas particles, entropy may increase or decrease but the magnitude of ∆S will be relatively small (N2(g)+O2(g)->2NO(g) ∆S≈0)
How will mixing of gas particles affect ∆S
-(consider the mixing of equimolar(constant volume) gases at constant pressure, where before mixing, each gas has the same volume and pressure. After mixing, each has expands to occupy the whole container hence the volume of each has doubles. The pressure of each gas is reduced by half but total pressure remains constant)
As the volume available for each gas is increased, there are more ways to distribute the particles and their energy. Thus entropy increases
-Similarly, when a gas expands at constant pressure the volume available for distribution of particles increases. Entropy increases as there are more ways that the particles and the energy can be distributed.
How will the mixing of liquid particles affect ∆S
-When liquids with similar polarities are mixed together, entropy increases. This is because total volume increases and hence there are more ways to distribute the particles and their energy
How will the dissolution of an ionic solid affect ∆S
Entropy increases -> because the ions in the solid are free to move in solution (no longer restricted within ionic lattice structure as ionic solid is broken down, and ions are free to move about solution)
Entropy decreases->because water molecules become restricted in motion as they arrange themselves around the ions
(Depending on which is more significant, ∆S>< 0)
