A lead-tin (Pb-Sn) alloy has a bulk elemental composition of 10wt% Sn Assuming that it is at a temperature of 400 °C and fully liquid, then cooled under equilibrium conditions. A: At what temperature does the first solid start to form

A lead-tin (Pb-Sn) alloy has a bulk elemental composition of 10wt% Sn Assuming that it is at a temperature of 400 °C and fully liquid, then cooled under equilibrium conditions. A: At what temperature does the first solid start to form

Chemistry: Principles and Reactions

8th Edition

ISBN:9781305079373

Author:William L. Masterton, Cecile N. Hurley

Publisher:William L. Masterton, Cecile N. Hurley

Chapter16: Spontaneity Of Reaction

Section: Chapter Questions

Problem 48QAP

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Hydrogen has been suggested as the fuel of the future. One way to store it is to convert it to a compound that can be heated to release the hydrogen. One such compound is calcium hydride, Cal-12. This compound has a heat of formation of -186.2 kJ/mol and a standard entropy of 42.0 J/mol K. What is the minimum temperature to which calcium hydride would have to be heated to produce hydrogen at one atmosphere pressure?
Data are given in Appendix 1 for white phosphorus, P4(s). P4(g) has the following thermodynamic values: Hf=58.9kJ/mol , S=280.0J/kmol . What is the temperature at which white phosphorus sublimes at 1 atm pressure?
Using data from Appendix 4, calculate H, G, and K (at 298 K) for the production of ozone from oxygen: 3O2(g)2O3(g) At 30 km above the surface of the earth, the temperature is about 230. K and the partial pressure of oxygen is about 1.0 103 atm. Estimate the partial pressure of ozone in equilibrium with oxygen at 30 km above the earth's surface. Is it reasonable to assume that the equilibrium between oxygen and ozone is maintained under these conditions? Explain.
The following data were collected for the reaction, H2(g) + L(g) ** - HI(g), at equilibrium at 25°C: [HJ = 0.10 mol L-1, [IJ = 0.20 mol L"\ [HI] = 4.0 mol L’1 Calculate the equilibrium constant for the reaction at this temperature.
An important source of copper is from the copper ore, chalcocite, a form of copper(I) sulfide. When heated, the Cu2S decomposes to form copper and sulfur described by the following equation: Cu2S(s)Cu(s)+S(s) (a) Determine G298 for the decomposition of Cu2S(s). (b) The reaction of sulfur with oxygen yields sulfur dioxide as the only product. Write an equation that describes this reaction, and determine G298 for the process. (c) The production of copper from chalcocite is performed by roasting the Cu2S in air to produce the Cu. By combining the equations from Parts (a) and (b), write the equation that describes the roasting of the chalcocite, and explain why coupling these reactions together makes for a more efficient process for the production of the copper.
The major industrial use of hydrogen is in the production of ammonia by the Haber process: 3H2(g)+N2(g)2NH3(g) a. Using data from Appendix 4, calculate H, S, and G for the Haber process reaction. b. Is the reaction spontaneous at standard conditions? c. At what temperatures is the reaction spontaneous at standard conditions? Assume H and S do not depend on temperature.
Three reactions very important to the semiconductor industry are The reduction of silicon dioxide to crude silicon, SiO2(s) + 2 C(s) → Si(s) + 2 CO(g) ΔrH° = 689.9 kJ/mol The formation of silicon tetrachloride from crude silicon, Si(s) + 2 Cl2(g) → SiCl4(g) ΔrH° = −657.01 kJ/mol The reduction of silicon tetrachloride to pure silicon with magnesium, SiCl4(g) + 2 Mg(s) → 2 MgCl2(s) + Si(s) ΔrH° = −625.6 kJ/mol Calculate the overall enthalpy change when 1.00 mol sand, SiO2, changes into very pure silicon by this series of reactions.
Use the standard free energy of formation data in Appendix G to determine the free energy change for each of the following reactions, which are run under standard state conditions and 25 C. Identify each as either spontaneous or nonspontaneous at these conditions. (a) MnO2(s)Mn(s)+O2(g) (b) H2(g)+Br2(l)2HBr(g) (c) Cu(s)+S(g)CuS(s) (d) 2LiOH(s)+CO2(g)Li2CO3(s)+H2O(g) (e) CH4(g)+O2(g)C(s,graphite)+2H2O(g) (f) CS2(g)+3Cl2(g)CCl4(g)+S2Cl2(g)
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Calculate the equilibrium partial pressure of NO2 and N2O4.