Definitions
Enthalpy/Heat
Gibb's Free Energy/Work
Internal Energy/Positional Entropy
Entropy
100
What is the first law of thermodynamics and give the best simple equation to describe it.
The energy of the universe is conserved. The change in energy of the universe = 0.
100
Calculate the standard reaction enthalpy of the following reaction: SO3(g) + H2O(l) --> H2S(g) + 2O2(g) Enthalpy of formation: SO3(g):-395.72 kJ/mol, H2O(l):-285.83 kJ/mol, H2S(g):-20.63 kJ/mol, O2(g): 0 kJ/mol.
660.92 kJ/mol
100
What sign does the change in Gibb's Free Energy of formation have for a nonstabile compound?
positive.
100
What are the translational and rotational energies for a mole of CH4?
3/2RT for both.
100
True or False: If the number of moles of gas does not change in a chemical reaction, then the change in entropy will equal 0.
False.
200
What is the change in enthalpy of formation and change in Gibb's Free Energy of formation for O2(g)?
0. Standard state.
200
Given the following reaction, estimate the heat released using the bond enthalpies: CH4(g) + 2O2(g) --> CO2(g) + 2H2O(g).
806 kJ/mol released.
200
For a constant volume of 3 L, how much work is done by an ideal gaseous system at 1 atm?
0.
200
How much residual entropy does CO2 have in its crystal form at T=0?
0. Co2 is symmetrical.
200
What are the signs of the change in entropy for the universe, system, and surroundings for a nonspontaneous exothermic reaction?
universe=-, surroundings=+, system=-
300
Define internal energy in your own words based on statistical thermodynamics.
The motion of individual molecules and the energy associated with that motion.
300
10 grams of methane are burned in a calorimeter with 200 mL of water. If the heat capacity of the calorimeter is 79 J/C and the change in temperature is 2.5 C, how much heat is evolved per gram of methane burned? (specific heat of water=4.184 J/gC, answer in J/g)
228.95 J/g
300
Is C(diamond) or C(graphite) more stabile? What would be the sign of the change in Gibb's Free energy of reaction of C(graphite)-->C(diamond)? Is this reaction spontaneous or nonspontaneous?
C(graphite) more stabile. Positive, nonspontaneous.
300
What is the internal energy associated with the rotation of 3 molecules of CO2?
3kT, linear.
300
Which reaction has the highest change in entropy? SO3(g) + H2O(l) --> H2S(g) + 2O2(g) 2H2O2(l) --> 2H2O(l) + O2(g) SO3(g) + H2O(g) --> H2SO4(l)
SO3(g) + H2O(l) --> H2S(g) + 2O2(g)
400
What is the definition of specific heat? Would a higher or lower specific heat emit a smaller quantity of heat?
The amount of heat energy that must be absorbed to increase the temperature of one gram of a substance by one degree Celcius. The higher specific heat would emit a smaller quantity of heat.
400
Calculate the standard reaction enthalpy for the following reaction: 3Fe2O3(s) + CO(g) --> 2Fe3O4(s) + CO2(g) given Fe2O3(s) + 3CO(g) --> 2Fe(s) + 3CO2(g) H=-14 kJ 3FeO(s) + CO2(g) --> Fe3O4(s) + CO(g) H=11 kJ Fe(s) + CO2(g) --> FeO(s) + CO(g) H=-1 kJ
-26 kJ
400
For the reaction H2SO4(l) --> H2S(g) + 2O2(g), calculate the work done on the system if the pressure is constant at 1 atm and has a temperature of 48 degrees C for the conversion of 1 moles of H2SO4(l) to H2S(g). Assume the gases are ideal.
-8006.87 J
400
Which one has the largest positional entropy, 10 molecules of CH4 or 2 molecules of BH2Cl?
BH2Cl. CH4 is symmetrical.
400
Would the change in entropy be positive or negative for O2(g, 8 atm) --> O2(g, 3 atm)?
positive. As pressure increases, entropy decreases.
500
What is an extensive property and what is an intensive property? State which of the following is extensive and which are intensive: mass, temperature, enthalpy, volume, pressure, entropy, density, Gibb's Free Energy.
Extensive: Depends on amount of material or size of system. Mass, volume, enthalpy, entropy, Gibb's Free Energy. Intensive: Doesn't depend on amount. Temperature, pressure, density.
500
If 50 grams of water at 20 degrees C is mixed with 10 grams of water at 100 degrees C, what will be the temperature of the 60 grams of water at equilibrium?
33.33 degrees C
500
For the given reaction at room temperature, NH4Cl(s) --> HCl(g) + NH3(g), calculate the change in Gibb's Free Energy of reaction (in kJ). Above or below what temperature will this reaction be spontaneous? NH4Cl(s):H=-314.43 kJ/mol, S=94.6 J/Kmol HCl(g):H=-92.31 kJ/mol, S=186.91 J/Kmol NH3(g):H=-46.11 kJ/mol, S=192.45 J/Kmol
91.15 kJ. Above 618.1 K.
500
Which of the following molecules will have an actual residual entropy closest to the predicted residual entropy if you have 1 mole of each? BrCl, FI, CN, CO Electronegativities: Br:2.96, Cl:3.16, F:3.98, I:2.66, C:2.5, N:3, O:3.5
BrCl
500
What would be the change in entropy of a cup of coffee if 500 kJ of energy is reversibly transferred to the coffee at 57 degrees C?
1.52 kJ/K.
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