07:44The Second Law of Thermodynamics: Heat Flow, Entropy, and MicrostatesProfessor Dave Explains509views
Multiple ChoiceAn ideal gas is allowed to expand at constant temperature. What are the signs of ∆H, ∆S & ∆G.1367views2rank7comments
Multiple ChoiceConsider the freezing of liquid water at 30°C. For this process what are the signs for ∆H, ∆S, and ∆G?1765views1rank4comments
Multiple ChoicePredict the sign of ∆S in the system for each of the following processes:a) Ag+ (aq) + Br - (aq) → AgBr (s)b) CI2 (g) → 2 CI - (g)c) CaCO3 (s) → CaO (s) + CO2 (g)d) Pb (s) at 50°C → Pb (s) at 70°C2070views4rank3comments
Multiple ChoiceFor each of the following reactions state the signs of ∆H (enthalpy) and ∆S (entropy):a) Fusion of ice.b) Sublimation of CO2c) Vaporization of aqueous water.d) Deposition of chlorine gas.e) Condensation of water vapor. 1753views2rank3comments
Multiple ChoiceDiethyl ether (C4H10O2, MW = 90.1 g/mol) has a boiling point of 35.6oC and heat of vaporization of 26.7 kJ/mol. What is the change in entropy (in kJ/K) when 3.2 g of diethyl ether at 35.6oC vaporizes at its boiling point?1343views1rank8comments
Multiple ChoiceUsing standard enthalpy and entropy values, calculate ΔG for the production of NH4NO3 at 20.0℃. 2 NH3 (g) + 2 O2 (g) → NH4NO3 (s) + H2O (l)266views
Multiple ChoiceIn order to calculate ΔH° for a reaction which of the following sets represents numerical values that would be required?200views
Multiple ChoiceCalculate the equilibrium constant for the formation of NO2 (g) from NO (g) and O2 (g) at 405 K. 2 NO (g) + O2 (g) → 2 NO2 (g)267views
Multiple ChoiceWhich reaction is most likely to have a positive ∆S of reaction?a) SiO2 (s) + 3 C (s) → SiC (s) + 2 CO (g)b) 6 CO2 (g) + 6 H2O (g) → C6H12O6 (s) + 6 O2 (g)c) CO (g) + Cl2 (g) → COCl2 (g)d) 3 NO2 (g) + H2O (l) → 2 HNO3 (l) + NO (g)251views2rank1comments
Multiple ChoiceIdentify sign of entropy changes for the following processes.1) freezing water to form ice2) ideal gas allowed to expand in a closed container at constant T3) mixing of two gases into one container4) NH2 (g) (1atm) → NH2 (g) (3 atm)5) gas mixture transferred from larger to smaller container252views2rank
Multiple ChoiceSelect correct statement(s) below:a) gaseous CO2 has higher entropy in 2 L container compared to in 5 L containerb) N2O (g) contains higher standard molar entropy then HI (g)c) NaHCO3 (aq) + HC2H3O2 (aq) → NaC2H3O2 (aq) + H2O (l) + CO2 (g) has a negative ∆Sd) evaporation of water at 100 °C involves greater ∆S than evaporation at 112 °C240views2rank1comments
Textbook QuestionTwo different gases occupy the two bulbs shown here. Consider the process that occurs when the stopcock is opened, assuming the gases behave ideally. (d) How does the process affect the entropy of the surroundings? 585views
Textbook QuestionWhich of the following reactions has ∆Ssys> 0? (a) N2(g) + 3H2(g) -> 2NH3(g) (b) Ag+(aq) + Cl-(aq) -> AgCl(s) (c) 2H2O2(aq) -> 2H2O(l) + O2(g) (d) 2I(g) -> I2(g)599views
Textbook QuestionIf energy can flow in and out of the system to maintain a constant temperature during the process, what can you say about the entropy change of the surroundings as a result of this process? 343views
Textbook QuestionIsomers are molecules that have the same chemical formula but different arrangements of atoms, as shown here for two isomers of pentane, C5H12. (b) Which isomer do you expect to have the higher standard molar entropy? Explain.745views
Textbook QuestionIndicate whether each statement is true or false. (a) ΔS is a state function. (b) If a system undergoes a reversible change, the entropy of the universe increases. (c) If a system undergoes a reversible process, the change in entropy of the system is exactly matched by an equal and opposite change in the entropy of the surroundings. (d) If a system undergoes a reversible process, the entropy change of the system must be zero.871views
Textbook QuestionThe normal boiling point of Br21l2 is 58.8 °C, and its molar enthalpy of vaporization is ΔHvap = 29.6 kJ>mol. (a) When Br21l2 boils at its normal boiling point, does its entropy increase or decrease?886views
Textbook QuestionThe element gallium (Ga) freezes at 29.8 °C, and its molar enthalpy of fusion is ΔHfus = 5.59 kJ>mol. (a) When molten gallium solidifies to Ga(s) at its normal melting point, is ΔS positive or negative?1261views
Textbook QuestionIndicate whether each statement is true or false. (c) In a certain spontaneous process the system undergoes an entropy change of 4.2 J>K; therefore, the entropy change of the surroundings must be -4.2 J>K.228views
Textbook QuestionConsider the gas-phase reaction of AB3 and A2 molecules: (a) Write a balanced equation for the reaction. (b) What is the sign of the entropy change for the reaction?744views
Textbook Question(a) Does the entropy of the surroundings increase for spontaneous processes?511views
Textbook Question(b) In a particular spontaneous process the entropy of the system decreases. What can you conclude about the sign and magnitude of ΔSsurr?342views
Textbook QuestionIdeal gases A (red spheres) and B (blue spheres) occupy two separate bulbs. The contents of both bulbs constitute the initial state of an isolated system. Consider the process that occurs when the stopcock is opened. (c) How dpes this process illustrate the second law of thermodynamics?301views
Textbook QuestionRank the situations represented by the following drawings according to increasing entropy.287views
Textbook QuestionTwo systems, each composed of two particles represented by circles, have 20 J of total energy. Which system, A or B, has the greater entropy? Why?381views
Textbook QuestionTwo systems, each composed of three particles represented by circles, have 30 J of total energy. How many energetically equivalent ways can you distribute the particles in each system? Which system has greater entropy? 1391views
Textbook Question(a) In a chemical reaction, two gases combine to form a solid. What do you expect for the sign of ΔS?1230views
Textbook QuestionWithout doing any calculations, determine the sign of ΔSsys for each chemical reaction. b. CH2 ' CH2( g) + H2( g) ¡ CH3CH3( g)431views1rank
Textbook QuestionWithout doing any calculations, determine the sign of ΔSsys for each chemical reaction. a. 2 KClO3(s) ¡ 2 KCl(s) + 3 O2( g)3330views
Textbook QuestionWithout doing any calculations, determine the signs of ΔSsys and ΔS surr for each chemical reaction. In addition, predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction is spontaneous. a. C3H8( g) + 5 O2( g) ¡ 3 CO2( g) + 4 H2O( g) ΔH° rxn = -2044 kJ2615views1comments
Textbook QuestionFor each of the following pairs, predict which substance possesses the larger entropy per mole: (a) 1 mol of O21g2 at 300 °C, 0.01 atm, or 1 mol of O31g2 at 300 °C, 0.01 atm909views
Textbook QuestionPredict the sign of the entropy change of the system for each of the following reactions: (d) Al2O31s2 + 3 H21g2¡2 Al1s2 + 3 H2O1g21431views
Textbook QuestionPredict the sign of the entropy change of the system for each of the following reactions: (c) 3 C2H21g2¡C6H61g2873views
Textbook QuestionPredict the sign of the entropy change of the system for each of the following reactions: (b) CaCO31s2¡CaO1s2 + CO21g2467views
Textbook QuestionPredict the sign of the entropy change of the system for each of the following reactions: (a) N21g2 + 3 H21g2¡2 NH31g2610views
Textbook QuestionDefine entropy, and give an example of a process in which the entropy of a system increases.506views
Textbook QuestionPredict the sign of ΔSsys for each of the following processes: (d) Calcium phosphate precipitates upon mixing Ca1NO3221aq2 and 1NH423PO41aq2.524views
Textbook QuestionPredict the sign of ΔSsys for each of the following processes: (c) Gaseous CO reacts with gaseous H2 to form liquid methanol, CH3OH.575views
Textbook QuestionPredict the sign of ΔSsys for each of the following processes: (a) Molten gold solidifies.1256views1rank
Textbook QuestionPredict the sign of ΔSsys for each of the following processes: (b) Gaseous Cl2 dissociates in the stratosphere to form gaseous Cl atoms.586views
Textbook QuestionPredict the sign of the entropy change in the system for each of the following processes. (a) A solid sublimes. (b) A liquid freezes. (c) AgI precipitates from a solution containing Ag+ and I- ions. (d) Gaseous CO2 bubbles out of a carbonated beverage.544views
Textbook QuestionCyclopropane and propylene are isomers that both have the formula C3H6. Based on the molecular structures shown, which of these isomers would you expect to have the higher standard molar entropy at 25 °C? 1957views
Textbook QuestionThe standard entropies at 298 K for certain group 4A elements are: C(s, diamond) = 2.43 J>mol@K, Si1s2 = 18.81 J>mol@K, Ge1s2 = 31.09 J>mol@K, and Sn1s2 = 51.818 J>mol@K. All but Sn have the same (diamond) structure. How do you account for the trend in the S° values?947views1rank
Textbook QuestionHow does the molar entropy of a substance change with increasing temperature?842views
Textbook QuestionThree of the forms of elemental carbon are graphite, diamond, and buckminsterfullerene. The entropies at 298 K for graphite and diamond are listed in Appendix C. (b) What would you expect for the S° value of buckminsterfullerene (Figure 12.49, p. 509) relative to the values for graphite and diamond? Explain.925views
Textbook QuestionFor each pair of substances, choose the one that you expect to have the higher standard molar entropy (S°) at 25 °C. Explain your choices. e. NO2( g); CH3CH2CH3( g)1588views
Textbook QuestionRank each set of substances in order of increasing standard molar entropy (S°). Explain your reasoning. b. H2O(s); H2O(l ); H2O( g)521views
Textbook QuestionRank each set of substances in order of increasing standard molar entropy (S°). Explain your reasoning. a. NH3( g); Ne( g); SO2( g); CH3CH2OH( g); He( g)2196views2rank
Textbook QuestionWhich state has higher entropy? Explain in terms of probability. (a) A perfectly ordered crystal of solid nitrous oxide or a disordered crystal in which the molecules are oriented randomly (b) Quartz glass (an amorphous solid) or a quartz crystal539views
Textbook QuestionRank each set of substances in order of increasing standard molar entropy (S°). Explain your reasoning. c. C(s, graphite); C(s, diamond); C(s, amorphous)695views
Textbook QuestionFor a certain chemical reaction, ΔH° = -35.4 kJ and ΔS° = -85.5 J>K. (b) Does the reaction lead to an increase or decrease in the randomness or disorder of the system?616views
Textbook QuestionWhich state in each of the following pairs has the higher entropy per mole of substance? (d) CO2 at STP or CO2 at 100 °C and 0.1 atm568views1rank
Textbook QuestionWhich state in each of the following pairs has the higher entropy per mole of substance? (a) H2 at 25 °C in a volume of 10 L or H2 at 25 °C in a volume of 50 L410views
Textbook QuestionWhich state in each of the following pairs has the higher entropy per mole of substance? (d) Water vapor at 150 °C and 1 atm or water vapor at 100 °C and 2 atm362views
Textbook QuestionWhich state in each of the following pairs has the higher entropy per mole of substance? (b) N2 at STP or N2 at 0 °C and 10 atm363views1rank
Textbook QuestionWhich state in each of the following pairs has the higher entropy per mole of substance? (a) Ice at -40 °C or ice at 0 °C302views
Textbook QuestionMake a rough, qualitative plot of the standard molar entropy versus temperature for methane from 0 K to 298 K. Incorporate the following data into your plot: mp = -182 °C; bp = -164 °C; °S = 186.2 J/(K*mol) at 25 °C.426views
Textbook QuestionAn isolated system is one that exchanges neither matter nor energy with the surroundings. What is the entropy criterion for spontaneous change in an isolated system? Give an example of a spontaneous process in an isolated system.243views
Textbook QuestionGive an equation that relates the entropy change in the surroundings to the enthalpy change in the system. What is the sign of ∆Ssurr for the following? (a) An exothermic reaction (b) An endothermic reaction874views
Textbook QuestionConsider a twofold expansion of 1 mol of an ideal gas at 25 °C in the isolated system shown in Figure 18.1. (b) How does this process illustrate the second law of thermo-dynamics?298views
Textbook QuestionFor each of the following processes, indicate whether the signs of ΔS and ΔH are expected to be positive, negative, or about zero. (e) A piece of charcoal is combusted to form CO21g2 and H2O1g2.748views
Textbook QuestionThe reaction 2 Mg1s2 + O21g2¡2 MgO1s2 is highly spontaneous. A classmate calculates the entropy change for this reaction and obtains a large negative value for ΔS °. Did your classmate make a mistake in the calculation? Explain.310views
Textbook Question(a) For each of the following reactions, predict the sign of ΔH° and ΔS ° without doing any calculations. (i) 2 Mg1s2 + O21g2Δ2 MgO1s2 (ii) 2 KI1s2Δ2 K1g2 + I21g2 (iii) Na21g2Δ2 Na1g2 (iv) 2 V2O51s2Δ4 V1s2 + 5 O21g2788views
Textbook Question(b) Based on your general chemical knowledge, predict which of these reactions will have K 7 1. (i) 2 Mg1s2 + O21g2Δ2 MgO1s2 (ii) 2 KI1s2Δ2 K1g2 + I21g2 (iii) Na21g2Δ2 Na1g2 (iv) 2 V2O51s2Δ4 V1s2 + 5 O21g2344views
Textbook QuestionIndicate and explain the sign of ΔSuniv for each process. a. 2 H2( g) + O2( g) → 2 H2O (l ) at 298 K.519views2comments
Textbook QuestionIn chemical kinetics, the entropy of activation is the entropy change for the process in which the reactants reach the activated complex. Predict whether the entropy of activation for a bimolecular process is usually positive or negative.1412views
Textbook QuestionWhen most elastomeric polymers (e.g., a rubber band) are stretched, the molecules become more ordered, as illustrated here: Suppose you stretch a rubber band. (a) Do you expect the entropy of the system to increase or decrease?513views
Open QuestionWithout doing any calculations, determine the sign of δssys for each of the following chemical reactions.218views
Open QuestionWhich of the following liquid substances has the highest vapor pressure at its normal boiling point?201views
Open QuestionRank these systems in order of decreasing entropy. rank from highest to lowest entropy. to rank items as equivalent, overlap them.662views2rank1comments
Open QuestionWhat will the sign on ∆S be for the following reaction and why? 2 Mg(s) + O2(g) → 2 MgO(s)53views