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One of the reactions that destroys ozone in the upper atmosphere is NOg+O3gNO2g+O2g

Using data from Appendix 4, calculate G°and K (at

298 K) for this reaction.

Short Answer

Expert verified

Answer

The value of G°andK(at 298 K) for this reaction are -198kJ/moland 5.06×1034respectively.

Step by step solution

01

Step 1: Introduction to the Concept

The difference in the standard enthalpy of formation of the products and that of the reactants is used to calculate the standard Gibbs free energy change for a reaction G°measured at 25°C and 1 atm pressure.

ΔGRo=npΔGfo(Products)-nrΔGfo(Reactants)-----(1)

The pressure dependency of a reaction's free energy change is written as

GR°=-RTInK-----(2)

Here,R=8.314J/mol-KT=Temperature

02

Determination of ∆G°

The given reaction is NOg+O3gNO2g+O2g

Let's compute GR°at298K

GR°=1×Gf°NO2g+Gf°O2g-1×Gf°NOg+1×Gf°O3gGR°=1mole×52kJ/mol+1mole×0kJ/mol-1mole×87kJ/mol+1mole×163kJ/molGR°=52-87-163GR°=-198kJ/mol

03

Determination of K

From equation (2),

InK=-GR°RTInK=198kJ/mol0.008314kJ/mol-K×298KInK=79.91K=e79.91=5.06×1034

Therefore,G°is-198kJ/molandKis5.06×1034

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Most popular questions from this chapter

When the environment is contaminated by a toxic or potentially toxic substance (for example, from a chemical spill or the use of insecticides), the substance tends to disperse. How is this consistent with the second law of thermodynamics? In terms of the second law, which requires the least work: cleaning the environment after it has been contaminated or trying to prevent the contamination before it occurs? Explain.

Predict the sign of S°and then calculate S°for each of the following reactions

  1. H2(g)+12O2(g)H2O(I)
  2. 2CH3OH(g)+3O2(g)2CO2(g)+4H2O(g)
  3. HCl(g)H+(aq)+Cl-(aq)

Discuss the relationship between wmaxand the magnitude and sign of the free energy change for a reaction. Also discusswmax for real processes.

Using data from Appendix 4, Calculate G°for the following reaction that produce acetic acid:


Which reaction would you choose as a commercial method for producing acetic acid (CH3CO2H)? What temperature conditions would you choose for the reaction? Assume standard conditions and assume that ΔHoandΔGoare temperature-independent.

Impure nickel, refined by smelting sulfide ores in a blast furnace, can be converted into metal from 99.90% to 99.99% purity by the Mond process. The primary reaction involved in the Mond process is
Ni(s)+4CO(g)Ni(CO)4(g)
a. Without referring to Appendix 4, predict the sign ofS° for the preceding reaction. Explain.
b. The spontaneity of the preceding reaction is temperature-dependent. Predict the sign of SSUIT for this reaction. Explain.
c. For, Ni(CO)4(g),Ht°=-607kj/moland S°=417J-1mol-1 at 298 K. Using these values and data in Appendix 4, calculate H°andS° for the preceding reaction.
d. Calculate the temperature at which G°=0(K=1) for the preceding reaction, assuming that H°andS° do not depend on temperature.
e. The first step of the Mond process involves equilibrating impure nickel with COgandNiCO4gatabout 50°C. The purpose of this step is to convert as much nickel as possible into the gas phase. Calculate the equilibrium constant for the preceding reaction at 50.°C.
f. In the second step of the Mond process, the gaseousNiCO4g is isolated and heated at 227°C. The purpose of this step is to deposit as much nickel as possible as pure solid (the reverse of the preceding reaction). Calculate the equilibrium constant for the preceding reaction at 227°C.
g. Why is temperature increased for the second step of the Mond process?

h. The Mond process relies on the volatility of NiCO4 for its success. Only pressures and temperatures at which NiCO4, is a gas are useful. A recently developed variation of the Mond process carries out the first step at higher pressures and a temperature of 152°C. Estimate the maximum pressure of NiCO4gthat can be attained before the gas will liquefy at 152°C. The boiling point for NiCO4is 42°C, and the enthalpy of vaporization is29.0kJ/mol . (Hint: The phase-change reaction and the corresponding equilibrium expression are
NiCO4INiCO4gK=PNiCO4
NiCO4gwill liquefy when the pressure of role="math" NiCO4is greater than the K value.)

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