Interpretation:
Standard free energy (
Concept Introduction:
Free energy
Free energy (Gibbs free energy) is the term that is used to explain the total energy content in a thermodynamic system that can be converted into work. The free energy is represented by the letter
Decomposition reaction: The reaction breaking down compounds (such as carbonates, nitrates or hydroxides) by heating them is called thermal decomposition.
For example,
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CHEMISTRY-ALEK 360 ACCES 1 SEMESTER ONL
- a Calculate K1, at 25C for sulfurous acid: H2SO3(aq)H+(aq)+HSO3(aq) b Which thermodynamic factor is the most significant in accounting for the fact that sulfurous acid is a weak acid? Why?arrow_forwardImpure 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 of S for the above reaction. Explain. b. The spontaneity of the above reaction is temperature-dependent. Predict the sign of Ssurr, for this reaction. Explain c. For Ni(CO)4(g), Hfo=607KJ/mol and S = 417 J/K mol at 298 K. Using these values and data in Appendix 4, calculate H and S for the above reaction. d. Calculate the temperature at which G = 0 (K = 1) for the above reaction, assuming that H and S do not depend on temperature. e. The first step of the Mood process involves equilibrating impure nickel with CO(g) and Ni(CO)4(g) at about 50C. The purpose of this step is to convert as much nickel as possible into the gas phase. Calculate the equilibrium constant for the above reaction at 50.C. f. In the second step of the Mood process, the gaseous Ni(CO)4 is isolated and heated to 227C. 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 227C. g. Why is temperature increased for the second step of the Mood process? h. The Mond process relies on the volatility of Ni(CO)4 for its success. Only pressures and temperatures at which Ni(CO)4 is a gas are useful. A recently developed variation of the Mood process carries out the first step at higher pressures and a temperature of l52C. Estimate the maximum pressure of Ni(CO)4(g) that can be attained before the gas will liquefy at 152C. The boiling point for Ni(CO)4 is 42C and the enthalpy of vaporization is 29.0 kJ/mol. [Hint: The phase change reaction and the corresponding equilibrium expression are Ni(CO)4(l)Ni(CO)4(g)K=PNi(CO)4 Ni(CO)4(g) will liquefy when the pressure of Ni(CO)4 is greater than the K value.]arrow_forwardConsider the reaction of 2 mol H2(g) at 25C and 1 atm with 1 mol O2(g) at the same temperature and pressure to produce liquid water at these conditions. If this reaction is run in a controlled way to generate work, what is the maximum useful work that can be obtained? How much entropy is produced in this case?arrow_forward
- The free energy of formation of one mole of compound refers to a particular chemical equation. For each of the following, write that equation. a KBr(s) b CH3Cl(l) c H2S(g) d AsH3(g)arrow_forwardConsider the reaction of 1 mol H2(g) at 25C and 1 atm with 1 mol Br2(l) at the same temperature and pressure to produce gaseous HBr at these conditions. If this reaction is run in a controlled way to generate work, what is the maximum useful work that can be obtained? How much entropy is produced in this case?arrow_forwardAccording to a source, lithium peroxide (Li2O2) decomposes to lithium oxide (Li2O) and oxygen gas at about 195C. If the standard enthalpy change for this decomposition is 33.9 kJ/mol, what would you give as an estimate for the standard entropy change for this reaction? Explain.arrow_forward
- Consider the decomposition of red mercury(II) oxide under standard state conditions.. 2HgO(s,red)2Hg(l)+O2(g) (a) Is the decomposition spontaneous under standard state conditions? (b) Above what temperature does the reaction become spontaneous?arrow_forwardWhich of the following are spontaneous processes? a A cube of sugar dissolves in a cup of hot tea. b A rusty crowbar turns shiny. c Butane from a lighter burns in air. d A clock pendulum, initially stopped, begins swinging. e Hydrogen and oxygen gases bubble out from a glass of pure water.arrow_forwardThe combustion of acetylene, C2H2, is a spontaneous reaction given by the equation 2C2H2(g)+5O2(g)4CO2(g)+2H2O(l) As expected for a combustion, the reaction is exothermic. What is the sign of H? What do you expect for the sign of S? Explain the spontaneity of the reaction in terms of the enthalpy and entropy changes.arrow_forward
- Is the following reaction spontaneous as written? Explain. Do whatever calculation is needed to answer the question. CH4(g)+N2(g)HCN(g)+NH3(g)arrow_forwardWithout doing any calculations, predict the sign of rS for the following reaction: Zn(s) + 2 HCl(aq) ZnCl2(aq) + H2(g) (a) rS 0 (b) rS = 0 (c) rS 0arrow_forwardSilver carbonate, Ag2CO3, is a light yellow compound that decomposes when heated to give silver oxide and carbon dioxide: Ag2CO3(s)Ag2O(s)+CO2(g) A researcher measured the partial pressure of carbon dioxide over a sample of silver carbonate at 220C and found that it was 1.37 atm. Calculate the partial pressure of carbon dioxide at 25C. The standard enthalpies of formation of silver carbonate and silver oxide at 25C are 505.9 kJ/mol and 31.05 kJ/mol, respectively. Make any reasonable assumptions in your calculations. State the assumptions that you make, and note why you think they are reasonable.arrow_forward
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