Thermodynamics

What are the two factors that favor spontaneity of a process?
Explain how the signs and magnitudes of ΔH and ΔS are related to the spontaneity of a process and how they affect it.
Which of the following would guarantee that a reaction would be spontaneous at constant T and P?
The entropy of the system increases.
The Gibbs free energy of the system decreases.
The entropy of the system decreases and the entropy of the surroundings increases.
The entropy of the system increases and the entropy of the surroundings increases.
The enthalpy of the system decreases and the entropy of the surroundings increases.
For each of the following processes, tell whether the entropy of the system increases, decreases, or remains constant.
Melting one mole of ice to water at 0°C
Freezing one mole of water to ice at 0°C
Freezing one mole of water to ice at -10°C
Freezing one mole of water to ice at 0°C and then cooling it to -10°C
For each of the process in #4, tell whether the entropy of the universe increases, decreases, or remains constant.
Using the standard entropies of formation from the appendix, calculate the ΔS for each of the following reactions at standard temperature and pressure.
3NO2(g) + H2O(l) → 2HNO3(l) + NO(g)
SnO2(s) + 2CO(g) → 2CO2(g) + Sn(s)
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s)
Na2CO3(s) + 2HCl(g) → 2NaCl(aq) + H2O(l) + CO2(g)
Using the appendix, calculate the Gibbs free energy for each of the reactions in #6 using ΔG°=ΔH°-TΔS°.
Using the appendix, calculate ΔG°rxn for each of the reactions in #6 using ΔG°rxn=∑▒〖〖∆G〗_f^° Products〗 – ∑▒〖〖∆G〗_f^° Reactants〗.
Compare the results in problems #7 and 8, explain the differences.
For each of the reactions in #6, determine at what temperature there would be a change in the spontaneity of the reaction.
For each of the reactions in #6, determine ΔG of the reaction when the temperature is changed to 37°C and the following conditions:
P_(NO_2 ) = 0.15atm, PNO = 0.25atm
PCO = 0.10atm, P_(CO_2 ) = 0.15atm
[NaOH] = 0.10M, P_(H_2 ) = 1.5atm
None
PHCl = 2.5atm, [NaCl] = 2.0M, P_(CO_2 ) = 1.5atm
What must be true for the value of ΔG° for a reaction if:
K>>1
K = 1
K<<1 Given that Kp is 4.6x10-14 at 25°C for the reaction: 2Cl2(g) + 2H2O(g) ⇄ 4HCl(g) + O2(g) ΔH° = 115kJ Using the van’t Hoff Equation: Ln(K_(T_2 )/K_(T_1 ) ) = (∆H°)/R(1/T_1 -1/T_2 ), calculate Kp and Kc for the reaction at 400°C and 800°C. A mixture of 3.00moles of Cl2 and 3.00moles of CO is enclosed in a 5.00L flask at 600°C. At equilibrium, 3.3% of the Cl2 has been consumed according to the following equilibrium: CO(g) + Cl2(g) ⇄ COCl2(g) Calculate Kc for the reaction at 600°C. Calculate ΔG° for the reaction at 600°C. At sufficiently high temperatures chlorine gas dissociates according to the following reaction: Cl2(g) ⇄ 2Cl(g) At 800°C, the Kp for the reaction is 5.63x10-7 A sample originally contained Cl2 at 1.0atm and 800°C. Calculate the percent dissociation of Cl2 when the reaction has reached equilibrium. At what temperature would Cl2 (originally at 1.0atm) be 1% dissociated into Cl atoms? Using the values in the appendix for the standard enthalpies and entropies of formation, calculate the Kp at 25°C for the gas phase reaction: CO(g) + H2O(g) ⇄ CO2(g) + H2(g) Calculate the Kp for the reaction in problem #16 at 200°C by the same method. Calculate the Kp for the reaction in problem #16 using ΔG° values instead. Consider the reaction: H2(g) + I2(g) ⇄ 2HI(g) The following data show the equilibrium constant for this reaction measured at different temperatures. Use the data to find ΔH°rxn and ΔS°rxn for the reaction. Temperature (K) Kp 150 1.4x10-6 175 4.6x10-4 200 3.6x10-2 225 1.1 250 15.5 ΔG° = 173.1kJ at 25°C for the reaction: N2(g) + O2(g) ⇄ 2NO(g) Calculate Kp for this reaction at 25°C. At 25°C, ΔH° = 185.5kJ. Determine Kp for the reaction at 2400K.