Interpretation: the spontaneity of the given reaction is to be identified from the given options.
Concept introduction:
In Spontaneous process, energy transfer from higher concentration to lower, or the energy is dispersed.
Entropy (S) is the quantity to measure the dispersal of energy in the spontaneous processes.
The equation for finding
Equation for
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Chemistry & Chemical Reactivity
- What is the sign of the standard Gibbs free-energy change at low temperatures and at high temperatures for the explosive decomposition of TNT? Use your knowledge of TNT and the chemical equation, particularly the phases, to answer this question. (Thermodynamic data for TNT are not in Appendix G.) 2C7H5N3O6(s) 3N2(g) + 5H2O() + 7C(s) + 7CO(g)arrow_forwardThe free energy for a reaction decreases as temperature increases. Explain how this observation is used to determine the sign of either H or S.arrow_forwardWhat is the sign of the standard Gibbs free-energy change at low temperatures and at high temperatures for the synthesis of ammonia? 3H2(g) + N2(g) 2NH3(g)arrow_forward
- On the basis of your experience, predict which reactions are spontaneous: (a) PbO2(s)Pb(s)+O2(g)(b) N2(l)N2(g) at 25C (c) C6H12O6(s)C6H12O6(l) at 25C (d) Ca2+(aq)+CO32(aq)CaCO3(s)arrow_forwardUse the data in Appendix G to calculate the standard entropy change for H2(g) + CuO(s) H2O() + Cu(s)arrow_forwardThermite reactions have been used for welding metal parts such as railway rails and in metal refining. One such thermite reaction is Fe2O3(s)+2Al(s)Al2O3(s)+2Fe(s). Is the reaction spontaneous at room temperature under standard conditions? During the reaction, the surroundings absorb 851.8 kJ/mol of heat.arrow_forward
- What is meant by the standard free-energy change G for a reaction? What is meant by the standard free energy of formation Gf of a substance?arrow_forwardHow is the sign of q, heat, defined? How does it relate to the total energy of the system?arrow_forwardFor the reaction NO(g)+NO2(g)N2O3(g) , use tabulated thermodynamic data to calculate H and S. Then use those values to answer the following questions. (a) Is this reaction spontaneous at 25°C? Explain your answer. (b) If the reaction is not spontaneous at 25°C, will it become spontaneous at higher temperatures or lower temperatures? (c) To show that your prediction is accurate, choose a temperature that corresponds to your prediction in part (b) and calculate G . (Assume that both enthalpy and entropy are independent of temperature.)arrow_forward
- Consider 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_forwardWhat is the sign of the standard Gibbs free-energy change at low temperatures and at high temperatures for the formation of hydrogen sulfide from the elements? H2(g)+18S8(s)H2S(g)arrow_forwardFrom the values for G f given in Appendix 1, calculate G at 25C for each of the reactions in Question 19.arrow_forward
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