A) Using Statistical interperation, discuss :
how the numbe of thermally aviable states of reactants versus products affects equilibrium.
how the relative ground-state energies of reactants versus products affect equilibrium.
B) What are the inherent assumptions of the kinetic theory of gases?
C) What is residual entropy and what are its units? you may give an example to suppoet your reasoning.
Solution
Answer (a)
The effect of temperature on equilibrium has to do with the heat of reaction. Recall that for an endothermic reaction, heat is absorbed in the reaction, and the value of ?H?H is positive. Thus, for an endothermic reaction, we can picture heat as being a reactant:
heat + A ? B ?H=+
For an exothermic reaction, the situation is just the opposite. Heat is released in the reaction, so heat is a product, and the value of ?H?His negative:
A ? B + heat ?H=?
If we picture heat as a reactant or a product, we can apply Le Chatelier’s principle just like we did in our discussion on raising or lowering concentrations. For instance, if we raise the temperature on an endothermic reaction, it is essentially like adding more reactant to the system, and therefore, by Le Chatelier’s principle, the equilibrium will shift the right. Conversely, lowering the temperature on an endothermic reaction will shift the equilibrium to the left, since lowering the temperature, in this case, is equivalent to removing a reactant.
For an exothermic reaction, heat is a product. Therefore, increasing the temperature will shift the equilibrium to the left, while decreasing the temperature will shift the equilibrium to the right.
Answer (b)
Answer (c)
Residual entropy is the difference in entropy between a non-equilibrium state and crystal state of a substance close to absolute zero.
Its unit is J mol -1 K -1 .
A common example is the case of carbon monoxide, which has a very small dipole moment. As the carbon monoxide crystal is cooled to absolute zero, few of the carbon monoxide molecules have enough time to align themselves into a perfect crystal, (with all of the carbon monoxide molecules oriented in the same direction). Because of this, the crystal is locked into a state with 2 N different corresponding microstates, giving a residual entropy of  S = Nk ln(2), rather than zero.
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A) Using Statistical interperation- discuss - how the numbe of thermal.docx
1. A) Using Statistical interperation, discuss :
how the numbe of thermally aviable states of reactants versus products affects equilibrium.
how the relative ground-state energies of reactants versus products affect equilibrium.
B) What are the inherent assumptions of the kinetic theory of gases?
C) What is residual entropy and what are its units? you may give an example to suppoet your
reasoning.
Solution
Answer (a)
The effect of temperature on equilibrium has to do with the heat of reaction. Recall that for an
endothermic reaction, heat is absorbed in the reaction, and the value of ?H?H is positive. Thus,
for an endothermic reaction, we can picture heat as being a reactant:
heat + A ? B ?H=+
For an exothermic reaction, the situation is just the opposite. Heat is released in the reaction, so
heat is a product, and the value of ?H?His negative:
A ? B + heat ?H=?
If we picture heat as a reactant or a product, we can apply Le Chatelier’s principle just like
we did in our discussion on raising or lowering concentrations. For instance, if we raise the
temperature on an endothermic reaction, it is essentially like adding more reactant to the system,
and therefore, by Le Chatelier’s principle, the equilibrium will shift the right. Conversely,
lowering the temperature on an endothermic reaction will shift the equilibrium to the left, since
lowering the temperature, in this case, is equivalent to removing a reactant.
For an exothermic reaction, heat is a product. Therefore, increasing the temperature will shift the
equilibrium to the left, while decreasing the temperature will shift the equilibrium to the right.
2. Answer (b)
Answer (c)
Residual entropy is the difference in entropy between a non-equilibrium state and crystal state
of a substance close to absolute zero.
Its unit is J mol -1
K -1
.
A common example is the case of carbon monoxide, which has a very small dipole moment. As
the carbon monoxide crystal is cooled to absolute zero, few of the carbon monoxide molecules
have enough time to align themselves into a perfect crystal, (with all of the carbon monoxide
molecules oriented in the same direction). Because of this, the crystal is locked into a state with 2
N
different corresponding microstates, giving a residual entropy of  S = Nk ln(2), rather than
zero.
