Interpretation:
Free energy (
Concept Introduction:
Spontaneous process: A process which is initiated by itself, without the help of external energy source is called spontaneous process. All spontaneous process is associated with the decrease in free energy in the system.
Free energy
Free energy (Gibbs free energy) is the term that is used to explain the total energy content in a thermodynamic system that can be converted into work. The free energy is represented by the letter
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CHEMISTRY-ALEK 360 ACCES 1 SEMESTER ONL
- 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_forwardCalculate G at 355 K for each of the reactions in Question 17. State whether the reactions are spontaneous.arrow_forwarda Calculate K1, at 25C for phosphoric acid: H3PO4(aq)H+(aq)+H2PO4(aq) b Which thermodynamic factor is the most significant in accounting for the fact that phosphoric acid is a weak acid? Why ?arrow_forward
- a 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_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_forwardFor the reaction 2Cu(s)+S(s)Cu2S(s) H and G are negative and S is positive. a At equilibrium, will reactants or products predominate? Why? b Why must the reaction system be heated in order to produce copper(I) sulfide?arrow_forward
- According to a source, lithium peroxide (Li2O2) decomposes to lithium oxide (Li2O) and oxygen gas at about 195C. If the standard enthalpy change for this decomposition is 33.9 kJ/mol, what would you give as an estimate for the standard entropy change for this reaction? Explain.arrow_forwardPick the example with the highest entropy from each of the following sets. Explain your answers. a.Two opposing football teams just before the ball is snapped, two opposing football teams 1 second after the ball is snapped, two opposing football teams when the whistle is blown, ending the play b.A 10 copper/gold alloy, a 2 copper/gold alloy, pure gold c.A purse on which the strap just broke, a purse just hitting the ground, a purse on the ground with contents scattered d.Coins in a piggy bank, coins in piles containing the same type of coins, coins in stacks of the same type of coins e.A dozen loose pearls in a box, a dozen pearls randomly strung on a string, a dozen pearls strung on a string in order of decreasing sizearrow_forwardActually, 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_forward
- Is the following reaction spontaneous as written? Explain. Do whatever calculation is needed to answer the question. SO2(g)+H2(g)H2S(g)+O2(g)arrow_forwardThe free energy of formation of one mole of compound refers to a particular chemical equation. For each of the following, write that equation. a KBr(s) b CH3Cl(l) c H2S(g) d AsH3(g)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_forward
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