If you calculate a value for ∆G° for a reaction using the values of
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Chemistry: An Atoms First Approach
- Which contains greater entropy, a quantity of frozen benzene or the same quantity of liquid benzene at the same temperature? Explain in terms of the dispersal of energy in the substance.arrow_forwardThe molecular scale pictures below show snapshots of a strong acid at three different instants after it is added to water. Place the three pictures in the correct order so that they show the progress of the spontaneous process that takes place as the acid dissolves in the water. Explain your answer in terms of entropyarrow_forwardWhat is the third law of thermodynamics? What are standard entropy values, S, and how are these S values (listed in Appendix 4) used to calculate S for a reaction? How would you use Hesss law to calculate S for a reaction? What does the superscript indicate? Predicting the sign of S for a reaction is an important skill to master. For a gas-phase reaction, what do you concentrate on to predict the sign of S? For a phase change, what do you concentrate on to predict the sign of S? That is, how are Ssolid, Sliquid, and Sgas related to one another? When a solute dissolves in water, what is usually the sign of S for this process?arrow_forward
- The decomposition of diamond to graphite [C(diamond) C(graphite)] is thermodynamically favored, but occurs slowly at room temperature. a. Use fG values from Appendix L to calculate rG and Keq for the reaction under standard conditions and 298.15 K. b. Use fH and S values from Appendix L to estimate rG and Keq for the reaction at 1000 K. Assume that enthalpy and entropy values are valid at these temperatures. Does heating shift the equilibrium toward the formation of diamond or graphite? c. Why is the formation of diamond favored at high pressures? d. The phase diagram shows that diamond is thermodynamically favored over graphite at 20,000 atmospheres pressure (about 2 GPa) at room temperature. Why is this conversion actually done at much higher temperatures and pressures?arrow_forwardConsider the reaction of 1 mol H2(g) at 25C and 1 atm with 1 mol Br2(l) at the same temperature and pressure to produce gaseous HBr 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_forwardSolid NH4NO3 is placed in a beaker containing water at 25 C. When the solid has completely dissolved, the temperature of the solution is 23.5 C. (a) Was the process exothermic or endothermic? (b) Was the process spontaneous? (c) Did the entropy of the system increase? (d) Did the entropy of the universe increase?arrow_forward
- Through photosynthesis, plants build molecules of sugar containing several carbon atoms from carbon dioxide. In the process, entropy is decreased. The reaction of CO2with formic acid to form oxalic acid provides a simple example of a reaction in which the number of carbon atoms in a compound increases: CO2(aq)+HCOOH(aq)H2C2O4(aq) (a) Calculate the standard entropy change for this reaction and discuss the sign of S . (b) How do plants carry out reactions that increase the number of carbon atoms in a sugar, given the changes in entropy for reactions like this?arrow_forwardExplain why each of the following statements is incorrect. (a) Entropy increases in all spontaneous reactions. (b) Reactions with a negative free energy change (rG 0) are product-favored and occur with rapid transformation of reactants to products. (c) All spontaneous processes are exothermic. (d) Endothermic processes are never spontaneous.arrow_forwardYeast can produce ethanol by the fermentation of glucose (C6H12O6), which is the basis for the production of most alcoholic beverages. C6H12O6(aq) 2 C2H5OH() + 2 CO2(g) Calculate rH, rS, and rG for the reaction at 25 C. Is the reaction product- or reactant-favored at equilibrium? In addition to the thermodynamic values in Appendix L, you will need the following data for C6H12O6(aq): fH = 1260.0 kl/mol; S = 289 J/K mol; and fG = 918.8 kl/mol.arrow_forward
- For each process, predict whether entropy increases or decreases, and explain how you arrived at your prediction. 2 CO2(g) → 2 CO(g) + O2(g) NaCl(s) → NaCl(aq) MgCO3(s) → MgO(s) + CO2(g)arrow_forwardFor the decomposition of formic acid, HCOOH(l)H2O(l)+CO(g) H = +29 kJ/mol at 25C. a Does the tendency of this reaction to proceed to a state of minimum energy favor the formation of water and carbon monoxide or formic acid? Explain. b Does the tendency of this reaction to proceed to a state of maximum entropy favor the formation of products or reactants? Explainarrow_forwardIn muscle cells under the condition of vigorous exercise, glucose is converted to lactic acid (lactate),CH3CHOHCOOH, by the chemical reaction C6H12O6 2 CH3CHOHCOOHrG = 197 kJ/mol (a) If all of the Gibbs free energy from this reaction wereused to convert ADP to ATP, calculate how many molesof ATP could be produced per mole of glucose. (b) The actual reaction involves the production of 3 molATP per mole of glucose. Calculate the rG for thisoverall reaction. (c) Is the overall reaction in part (b) reactant-favored orproduct-favored?arrow_forward
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