For the following two reactions
the first reaction has a lower value of
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Chapter 20 Solutions
Physical Chemistry
- Silicon forms a series of compounds analogous to the al-kanes and having the general formula SinH2n+2. The first of these compounds is silane, SiH4, which is used in the electronics industry to produce thin ultrapure silicon films. SiH4(g) is somewhat difficult to work with because it is py-ropboric at room temperature—meaning that it bursts into flame spontaneously when exposed to air. (a) Write an equation for the combustion of SiH4(g). (The reaction is analogous to hydrocarbon combustion, and SiO2 is a solid under standard conditions. Assume the water produced will be a gas.) (b) Use the data from Appendix E to calculate ? for this reaction. (c) Calculate G and show that the reaction is spontaneous at 25°C. (d) Compare G for this reaction to the combustion of methane. (See the previous problem.) Are the reactions in these two exercises enthalpy or entropy driven? Explain.arrow_forwardOne of the components of polluted air is NO. It is formed in the high-temperature environment of internal combustion engines by the following reaction: N2(g)+O2(g)2NO(g)H=180KJ Why are high temperatures needed to convert N2 and O2 to NO?arrow_forwardDetermine rxnH 25 C for the following reaction: NO g O2 g NO2 g This reaction is a major participant in the formation of smog.arrow_forward
- The following equation represents a reversible decomposition: CaCO3(s)CaO(s)+CO2(g) Under what conditions will decomposition in a closed container proceed to completion so that no CaCO3 remains?arrow_forwardMonochloroethane (C2H5Cl) can be produced by the direct reaction of ethane gas (C2H6) with chlorine gas or by the reaction of ethylene gas (C2H4) with hydrogen chloride gas. The second reaction gives almost a 100% yield of pure C2H5Cl at a rapid rate without catalysis. The first method requires light as an energy source or the reaction would not occur. Yet G for the first reaction is considerably more negative than G for the second reaction. Explain how this can be so.arrow_forwardConsider the reaction H2(g)+Br2(g)2HBr(g) where H = 103.8 kJ/mol. In a particular experiment, equal moles of H2(g) at 1.00 atm and Br2(g) at 1.00 atm were mixed in a 1.00-L flask at 25C and allowed to reach equilibrium. Then the molecules of H2 at equilibrium were counted using a very sensitive technique, and 1.10 1013 molecules were found. For this reaction, calculate the values of K, G, and S.arrow_forward
- The reaction of carbon monoxide with hydrogen to form methanol is quite slow at room temperature. As a general rule, reactions go faster at higher temperatures. Suppose that you tried to speed up this reaction by increasing the temperature. (a) Assuming that rH does not change very much as the temperature changes, what effect would increasing the temperature have on rSsurroundings? (b) Assuming that rS for a reaction System does not change much as the temperature changes, what effect would increasing the temperature have on rSuniverse?arrow_forwardIn the reaction Ag,CO,(s) Ag,0(s) + CO,(g) increasing the temperature increases the amount of carbon dioxide formed at constant pressure. Is this reaction exothermic or endothermic? Explain your answer.arrow_forwardA stoichiometric mixture of CO(g) and H2(g) was allowed to react in two different 2.0L rigid containers at a constant temperature of 298K. The reaction is represented by the equation above. Diagram 1 represents the uncatalyzed reaction and diagram 2 represents the catalyzed reaction one hour after the reactants were mixed. Which of the following correctly explains the experimental results represented in the particle diagrams? A.) Although the reaction is thermodynamically favorable because ΔG°<0 based on the value of K, only the catalyzed reaction could proceed in one hour because its reactant molecules had a higher average kinetic energy. B.) Although the reaction is thermodynamically favorable because ΔG°<0 based on the value of K, only the catalyzed reaction could proceed in one hour because it has a lower activation-energy reaction pathway. C.) The reaction is not thermodynamically favorable because ΔG°>0 based on the value of K, but the addition of a catalyst improved the…arrow_forward
- 1) Use Hess's Law to determine AH for the following target reaction. 3 CO₂(g) + 4 H₂O(g) b) C3Hg(g) + 5 O₂(g) C(s) + O₂(g) -CO₂(g) 2 H₂(g) + O₂(g) 3 C(s) + 4 H₂(g) →→→ 2 H₂O(g) C3H8(g) AH = AH = ΔΗ ΔΗ = ??? -2043 kJ -393.5 kJ -483.6 kJarrow_forwardWhen exposed to UV light, phosgene decomposes according to the reaction COCl2 (g) → CO (g) + Cl2 (g) All the air is removed from a flask. The flask is then filled with phosgene to a pressure of 1.0 atm. The flask is sealed and exposed to UV light so the phosgene decomposes. The temperature remains constant during the decomposition. (a) What are the partial pressures of the CO and Cl2 after the decomposition of phosgene is complete? (answer: 1 atm each) (b) What is the total pressure in the flask after the decomposition of phosgene is complete? (answer: 2 atm)arrow_forwardFor the following reactions at constant pressure, choose the correct relationship between AH and AE. 2HF(g) → H2(g) + F2(g) ΔΗ>ΔΕ ΔΗ ΔΕ Ο ΔΗ ΔΕ ΔΗ<ΔΕ ΔΗ-ΔΕ depends on the conditionsarrow_forward
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