6. We may think of entropy, S, as a measure of order and disorder.
(a) CO2 vapor at 273K has molecular rotation, vibrations (four) and three degrees of kinetic energy (vx, vy, vz) and has higher entropy, S, than does solid CO2(s) at 195K having only lattice vibrations and possibly hindered rotations.
(b) Sugar, as a solid, has lower entropy than sugar dissolved in a liquid. The molecules in solution have molecular vibration, rotational and translational degrees of freedom. Solid, crystaline sugar has lattice vibrations.
(c) Obviously, a mixture is more disordered and has higher entropy than the same amounts of water and ethanol. This is an entropy of mixing.
7.
(a) Si(s) has more order than Si(s) + impurity and so Si(s) + impurity has higher entropy than pure silicon crystal, Si(s).
(b) Ice is an ordered crystaline structure; wate is a more or less random liquid. (There is some micro-structure to water). Water has higher entropy than ice.
(c) Iodine, I_2, vapor has higher S than I_2(s).
11.
(a)
(b) 
The above figure is the reverse of the problem so the entropy change going from liquid to gas would be positive = + 122 J/K.
(c) 
15.
21
The thing to do is compute the Gibbs Free energy 
We are given the enthalpies and we can look up the entropies all at 298K. Unfortunately,
our text does not give the entropy for cyclohexane. Its value is S^{(o)} = 298.24
J/mol-K.
The Gibbs free energy is 
and the enthalpy drives the reaction favoring products due to the negative Gibbs
free energy.
23
(a) 
= -673 kJ/mol - (298)(60.4)/1000 kJ/mol
Products favored by both the enthalpy and entropy terms.
(b) 
= 491.18 kJ/mol - (298)(197.67)/1000 kJ/mol = 439.28 kJ/mol > 0 and reactants
are favored. The enthalpy term dominates the process.
28
(a) 
= 117.36 kJ/mol - (298)168.59/1000 kJ/mol = 67.12 kJ/mol where we can look up the
and calculate the entropy 
.
(b) 
(c) 
31 
For 1Kg there are 1000g/32 = 31.3 moles and = 31.3 mole x (-623.6 kJ/mol) =
-19,488 kJ.
That is, like 
and depend on the number of moles and are therefore called extensive quantities.
39 
= -166.27 kJ/mol, 
K = 1.4 x 10^{29}. Negative means a large equilibrium constant, K. This favors products.
By the way, if you mix graphite, C(s), oxygen and hydrogen in stoichiometric amounts
do you think you will get methanol?
40 
(a) Large negative favors products.
(b) 
Since negative favors products K must be large (K > 1) and we see that that is true.
41 
This gives Ksp = 1.7 x 10^{-10}
Next,
Adding,
The overall K = 3.3 x 10^{-5}, the reaction is reactant favored.