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29 Nov 2019

The thermodynamic properties for areaction are related by the equation that defines the standard freeenergy, ?G?, in kJ/mol:
?G?=?H??T?S?
where ?H? is the standard enthalpy changein kJ/moland ?S? is the standard entropy changein J/(mol?K). A good approximation of the free energychange at other temperatures, ?GT, can also beobtained by utilizing this equation and assuming enthalpy(?H?) and entropy (?S?) change little withtemperature.

PartA

For the decomposition of calciumcarbonate, consider the following thermodynamic data:

?H?rxn 178.5kJ/mol

?S?rxn 161.0J/(mol?K)

Calculate the temperature in kelvins above which this reaction isspontaneous.

Express your answer to foursignificant figures and include the appropriate units.

The standard free energy change,?G?, and the equilibrium constantK for a reaction can be related by the followingequation:
?G?=?RTlnK
where T is the Kelvin temperature and R is equal to 8.314 J/(mol?K).

PartB

Calculate the equilibrium constant forthe following reaction at room temperature, 25 ?C:
CaCO3(s)?CaO(s)+CO2(g)

Express your answernumerically to three significant figures.

PART A (Unrelated)

The normalboiling point of Br2(l) is 58.8 ?C, andits molar enthalpy of vaporization is ?Hvap= 29.6 kJ/mol.

Calculatethe value of ?Swhen 1.70molof Br2(l) is vaporized at 58.8 ?C.

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Elin HesselLv2

17 Dec 2019

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Q1. Which of the following processes are spontaneous and which are non spontaneous.
a) The combustion of natural gas
b) Extraction of Aluminum metal from its ore
c) A ball rolling down a hill
d) A bike going up a hill

Q2. Predict the entropy change (positive or negative) for the following processes/reactions
a) a lake freezing
b) weeding a garden
c) N2(g) + 2 H2(g) ? N2H4 (g)
d) Mg(s) + 2H2O(l) ? Mg(OH)2 (s) + H2(g)

Q3. The element Cesium (Cs) freezes at 28.4 C and its molar enthalpy of fusion ΔH_fusion = 2.09 kJ/mol.
a) When molten Cs solidifies to Cs (s) at its normal melting point, is the entropy change ΔS positive or negative?
b) Calculate the entropy change S when 15.0 g of Cs(l) solidifies at 28.4 C.

Q4. Using the values for standard molar entropies ΔS_f° from the appendix in your textbook, calculate ΔS° for the following reactions.
a) Be(OH)₂ (s) ? BeO (s) + H2O (g)
b) Mg(OH)2 (s) + 2 HCl (g) ? MgCl2 (s) + 2H2O (l)
c) 2CH4(g) ? C2H6 (g) + H2(g)

Q5. Using the data in the appendix of your textbook, calculate the Gibbs free energy change ΔG° for the following reactions. In each case, indicate whether the reaction is spontaneous or not
a) H2 (g) + Cl2(g) ? 2HCl (g)
b) 2 POCl3 (g) ? 2 PCl3 (g) + O2 (g)

Q6. Consider the reaction 2 NO2 (g)---N2O4 (g)
a) Using the data in the appendix in your text, calculate the standard Gibbs free energy change (ΔG°) for the reaction at 298K.
b) For the above reaction, calculate the value of Keq at 298K
c) For the same reaction, calculate G at 298 K when the partial pressures for NO₂ and N2O4 are 0.40 atm and 0.36 atm, respectively.

Q7. Consider the reaction I2 (g) + Cl2 (g)----2 ICl (g) Kp = 81.9 at 298 K
a) Calculate the standard free energy change (ΔG°)
b) What will be the Free energy change when the above reaction is at equilibrium
c) Calculate G for the reaction at 298 K when PICl = 2.55 atm, PI2=0.325 atm and PCl2 = 0.221 atm

Q8. Consider the decomposition of Lead carbonate PbCO3 (s) ? PbO(s) + CO2 (g)
a) Calculate the Gibbs free energy change (ΔG°) for the reaction at298 K.
b) Calculate G for the reaction at 400 K.
c) Write down the equilibrium expression and calculate the value of Keq at 298 K
d) Calculate the partial pressure of CO2 at 298 K. (Hint: Look at the equilibrium expression and the value of Keq at 298 K)

Q9. For the reaction: 2Al(s) + 3/2 O2(g) ? Al2O3(s), ΔH^o_rxn = -1617 kJ/mol and ΔH^o_rxn = -1577 kJ/mol. Use this data to calculate ΔS^o_rxn reaction at 298 K.

Q10. Calculate the ΔG^o for the following reaction using the data from your text:
2SO2(g) + O2(g) ? 2SO3(g)

Q11. Using the thermodynamic data available from the Appendix(?Goâs), calculate ΔG^o rxn and calculate the equilibrium constant(K) for the reaction at 25 oC:
CaCO3(s) ? CaO(s) + CO2(g)

Q12. What is the minimum temperature required for the spontaneous conversion of CCl4(l) to CCl4(g) when ΔH°(vap) is 57.3 kJ/mol andΔS°(vap) is 164 J/(mol K)? reaction: CCl4(l) ? CCl4(g)

Q13. Given the following
Fe2O3(s) + 3CO(g) . ? 2Fe(s) + 3CO2(g) ΔG° = 29.4 kJ
3Fe2O3(s) + CO(g) . ? 2Fe3O4(s) + CO2(g) ΔG° = 61.6 kJ
Calculate ΔG° for Fe(s) + Fe2O3(s) + CO2(g) ? Fe3O4(s) +CO(g)

Q14. Calculate ΔG° rxn for 2CO(g) + O2(g) ? 2CO2(g) and then calculate ΔG for the reaction at 298K; if the pressure of CO =20. atm,P O2 = 10. atm and P CO2= 0.50 atm. Will increasing the pressure of the reactants make the reaction more or less spontaneous? Explain using your calculations and Le Chatelierâs principle.

Q15. Write the reaction for photosynthesis (production ofC6H12O6(s) and oxygen from carbon dioxide and water as a gas).Calculate ?H, ? S, and ?G for the reaction at standard state. Is the reaction spontaneous?

blackferret405

DearChegg Lifesaver. Here are the requirements:

1.Use given values as stated in questions below.

2.Clearly State Answer

3.(Please) LEAVE A COMMENT if you are currently working on anyproblems.

4.Formany of these problems you will need to use tabulated thermodynamicdata. Use the Information provided after problem 17.

---------------------------------------Questions---------------------------------------------------

1.Write a balanced formation equation for HNO3 at standardconditions. For the answer, enter the sum all of the coefficientsin the balanced equation. (If thisis not an integer, enter it as a decimal, not a fraction.)

2.Calculate ?HÂ° for the following reaction:

SiO2(s)+ 4HF(g) ? SiF4(g) + 2H2O(g)

3.Use heat of formation data to determine ?HÂ° for the reaction:

2NH3(g)? N2(g) + 3H2(g)

4.Calculate the mass of methane that must be burned to provide enoughheat to convert 330.0 g of water at 37.0Â°C into steam at 124.0Â°C.(Assume that the H2Oproduced in the combustion reaction is steam rather than liquidwater.)

5.Acetylene burns in air according to the following equation:

C2H2(g)+ 5/2 O2(g) ? 2 CO2(g) + H2O(g)

with?HÂ° = -1255.8 kJ.

Giventhat ?HfÂ° for CO2(g) = -393.5 kJ/mol and ?HfÂ° for H2O(g) is -241.8kJ/mol, what is ?HfÂ° for C2H2(g)?

6.Given the following data:

HNO3(l)? 1/2N2(g) + 3/2O2(g) + 1/2H2(g) ?HÂ° = 174.1 kJ

2N2O5(g)? 2N2(g) + 5O2(g) ?HÂ° = -28.4 kJ

H2O(l)? H2(g) + 1/2O2(g) ?HÂ° = 285.8 kJ

Calculate?HÂ° for the reaction:

2HNO3(l)? N2O5(g) + H2O(l)

Notethat you should be able to answer this one without needing to useany additional information from the thermo table.

7.Hydrocarbons containing halogens are very useful molecules insynthetic chemistry. Use tabulated thermodynamic data as needed tocalculate ?HfÂ° for the reactionproduct in the equation shown below if ?HÂ° for the reaction is-177.66 kJ.

C2H4(g)+ Cl2(g) ? CH2ClCH2Cl(g)

8.Identify the following statements as true or false. (Use thedrop-down menu and select "True" or "False" for each. You must getall 6 correct.)

Allsystems become more disordered spontaneously.

Both?Ssys and ?Ssurr must equal zero at equilibrium.

Theentropy of the universe is constant; the energy of the universedecreases towards a minimum.

Allspontaneous processes release heat.

Ifa reaction is spontaneous, the reverse reaction is non-spontaneous.

Ifa process decreases the randomness of the particles of a system,the entropy of the system increases.

9.Use tabulated thermodynamic data to calculate ?SÂ° for the reaction:

PbO2(s)+ 2Ni(s) ? Pb(s) + 2NiO(s)

10.Calculate ?SÂ° for the combustion of ethane (C2H6) to form carbondioxide and gaseous water.

11.Urea ((NH2)2CO) can be formed from ammonia and carbon dioxide asshown in the following reaction. The ?HÂ° value for this synthesisis -134.0 kJ. Calculatethe ?HÂ°f for urea.

2NH3(g)+ CO2(g) ? (NH2)2CO(s) + H2O(l)

12.The ?SÂ° value for urea the synthesis reaction above is -424.0 J/K.Calculate SÂ° for urea.

Tries0/99

13.Calculate ?GÂ° for the synthesis of urea under standard conditions(298 K and 1 atm).

Tries0/99

14.Compute the standard free energy change for the following reaction.

O3(g)+ NO(g) ? NO2(g) + O2(g)

Tries0/99

15.The most important commercial process for generating hydrogen gasis the water-gas shift reaction:

CH4(g)+ H2O(g) ? CO(g) + 3H2(g)

Usetabulated thermodynamic data to find ?GÂ° for this reaction at thestandard temperature of 25Â°C.

16.Now calculate ?GÂ°1100 for this process when it occurs at 1100 K.

17.The molar enthalpy of fusion (?HÂ°) of fluorine is 0.260 kJ/mol, andthe molar entropy of fusion (?SÂ°) of fluorine is 4.851 J/mol K.Using this information,estimate the freezing point of fluorine. (You must answer inKelvin.)

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