Consider the thermal decomposition of
The equilibrium vapor pressures of
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Chemistry
- Adenosine triphosphate, ATP, is used as a free-energy source by biological cells. (See the essay on page 624.) ATP hydrolyzes in the presence of enzymes to give ADP: ATP(aq)+H2O(l)ADP(aq)+H2PO4(aq);G=30.5kJ/molat25C Consider a hypothetical biochemical reaction of molecule A to give molecule B: A(aq)B(aq);G=+15.0kJ/molat25C Calculate the ratio [B]/[A] at 25C at equilibrium. Now consider this reaction coupled to the reaction for the hydrolysis of ATP: A(aq)+ATP(aq)+H2O(l)B(aq)+ADP(aq)+H2PO4(aq) If a cell maintains a high ratio of ATP to ADP and H2PO4 by continuously making ATP, the conversion of A to B can be made highly spontaneous. A characteristic value of this ratio is [ATP][ADP][H2PO4]=500 Calculate the ratio [B][A] in this case and compare it with the uncoupled reaction. Compared with the uncoupled reaction, how much larger is this ratio when coupled to the hydrolysis of ATP?arrow_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_forwardHydrogen gas and iodine gas react to form hydrogen iodide. If 0.500 mol H2 and 1.00 mol I2 are placed in a closed 10.0-L vessel, what is the mole fraction of HI in the mixture when equilibrium is reached at 205C? Use data from Appendix C and any reasonable approximations to obtain K.arrow_forward
- Actually, the carbon in CO2(g) is thermodynamically unstable with respect to the carbon in calcium carbonate(limestone). Verify this by determining the standardGibbs free energy change for the reaction of lime,CaO(s), with CO2(g) to make CaCO3(s).arrow_forwardUse the data in Appendix J to calculate rG andKPat 25 C for the reaction 2HBr(g)+Cl2(g)2HCl(g)+Br2() Comment on the connection between the sign of rG and the magnitude ofKP.arrow_forwardA crucial reaction for the production of synthetic fuels is the production of H2 by the reaction of coal with steam. The chemical reaction is C(s) + H2O(g) CO(g) + H2(g) (a) Calculate rG for this reaction at 25 C, assuming C(s) is graphite. (b) Calculate Kp for the reaction at 25 C. (c) Is the reaction predicted to be product-favored at equilibrium at 25 C? If not, at what temperature will it become so?arrow_forward
- Elemental boron, in the form of thin fibers, can be made by reducing a boron halide with H2. BCl3(g) + 3/2 H2(g) B(s) + 3HCl(g) Calculate H, S, and G at 25 C for this reaction. Is the reaction predicted to be product favored at equilibrium at 25 C? If so, is it enthalpy driven or entropy driven?arrow_forwardElemental boron, in the form of thin fibers, can be made by reducing a boron halide with H2. BCl3(g) + 32 H2(g) B(s) + 3 HCl(g) Calculate rH, rS, and rG at 25 C for this reaction. Is the reaction predicted to be product-favored at equilibrium at 25 C? If so, is it enthalpy- or entropy-driven? [S for B(s) is 5.86 J/K mol.]arrow_forwarda 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_forward
- Explain how the entropy of the universe increases when an aluminum metal can is made from aluminum ore. Thefirst step is to extract the ore, which is primarily a formof A12O3, from the ground. After it is purified by freeingit from oxides of silicon and iron, aluminum oxide ischanged to the metal by an input of electrical energy. 2Al2O3(s)electricalenergy4Al(s)+3O2(g)arrow_forwardThe equilibrium constant for a certain reaction increases by a factor of 6.67 when the temperature is increased from 300.0 K to 350.0 K. Calculate the standard change in enthalpy (H) for this reaction (assuming H is temperature-independent).arrow_forwardConsider the reaction 2SO2(g)+O2(g)2SO3(g) (a) Calculate G at 25C. (b) If the partial pressures of SO2 and SO3 are kept at 0.400 atm, what partial pressure should O2 have so that the reaction just becomes nonspontaneous (i.e., G=+1.0 k J)?arrow_forward
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