Predict the order of the following reactions in terms of increasing ΔS:
(a)
(c)
(d)
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Chemistry: Principles and Reactions
- Cobalt(II) chloride hexahydrate, CoCl26H2O, is a bright pink compound, but in the presence of very dry air it loses water vapor to the air to produce the light blue anhydrous salt CoCl2. Calculate the standard free-energy change for the reaction at 25C: CoCl26H2O(s)CoCl2(s)+6H2O(g) Here are some thermodynamic data at 25C: What is the partial pressure of water vapor in equilibrium with the anhydrous salt and the hexahydrate at 25C? (Give the value in mmHg.) What is the relative humidity of air that has this partial pressure of water? The relative humidity of a sample of air is Relativehumidity=partialpressureofH2O(g)inairvaporpressureofwater100 What do you expect to happen to the equilibrium partial pressure over the hexahydrate as the temperature is raised? Explain.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_forwardSilicon 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_forward
- Consider these three reactions as the elementary steps in the mechanism for a chemical reaction.(i) Cl2 (g) + Pt (s) à 2Cl (g) + Pt (s) Ea = 1550 kJ ∆H = – 950 kJ(ii) Cl (g)+ CO (g) + Pt (s) à ClCO (g) + Pt (s) Ea = 2240 kJ ∆H = 575 kJ(iii) Cl (g) + ClCO (g) à Cl2CO (g) Ea = 2350 kJ ∆H = – 825 kJ e. Which reaction intermediate would be considered a catalyst (if any) and why?f. If you were to add 2700kJ of activation energy to the reaction, would you be able to make thereaction reverse itself (i.e. have the products become reactants)? Justify your answer.g. If you were to added a positive catalyst to step (iii) what would the end result be? Justify yourprediction.h. Your friend is looking at your graph and states that she believes that step (ii) is the ratedetermining step. Do you agree with her? Justify your reasoning.arrow_forwardFor the reaction BrO3– + 5Br–+ 6H+ → 3Br2 + 3H2O at a particular time, –Δ[BrO3–]/Δt = 1.5 × 10–2 M/s. What is –Δ[Br–]/Δt at the same instant?arrow_forwardA mole of XX reacts at a constant pressure of 43.0 atmatm via the reaction X(g)+4Y(g)→2Z(g), ΔH∘=−75.0 kJX(g)+4Y(g)→2Z(g), ΔH∘=−75.0 kJ Before the reaction, the volume of the gaseous mixture was 5.00 LL. After the reaction, the volume was 2.00 LL. Calculate the value of the total energy change, ΔE, in kilojoules.arrow_forward
- 6. In a study of glass etching, a chemist examines the reaction between sand (SiO₂) and hydrogen fluoride at 150°C: SiO₂ (s) + 4HF(g) SiF4(g) + 2H₂O(g) Predict the effect on [SiF4] when (a) H₂O(g) is removed; (b) some liquid water is added; (c) HF is removed; (d) some sand is removed.arrow_forwardA NASA spacecraft measures the rate R of at which atmospheric pressure on Mars decreases with altitude. The result at a certain altitude is: - 1 R=0.0296 kPa·km -4 Convert r to j·cm ala 4 J•cm x10 18 Ararrow_forwardConsider the reaction Mg(s)+Fe2+(aq)→Mg2+(aq)+Fe(s)Mg(�)+Fe2+(��)→Mg2+(��)+Fe(�) at 73 ∘C∘C , where [Fe2+]=3.80mol L−1[Fe2+]=3.80mol L−1 and [Mg2+]=0.210mol L−1[Mg2+]=0.210mol L−1 . What is the cell potential for the reaction Mg(s)+Fe2+(aq)→Mg2+(aq)+Fe(s)Mg(�)+Fe2+(��)→Mg2+(��)+Fe(�) at 73 ∘C∘C when [Fe2+]=3.80mol L−1[Fe2+]=3.80mol L−1 and [Mg2+]=0.210mol L−1[Mg2+]=0.210mol L−1. Assume that the standard cell potential does not depend on temperature. Express your answer to three significant figures and include the appropriate units.arrow_forward
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