Q&A Hero

Q: What is the entropy of 10 molecules in a system of 100 boxes?

Q: The sign (+ or -) of H is ________ and the sign (+ or -) of S is ________ for the evaporation of water.

Q: Chemical and physical changes can be classified as spontaneous or nonspontaneous. At 25C and 1 atm pressure the decomposition of water into hydrogen and oxygen is classified as ________, and the melting of ice is classified as ________.

Q: Which one of the following would be expected to have the lowest standard molar entropy, S, at 25C? A) C10H22(s) B) C10H22(l) C) C14H30(s) D) C14H30OH(l)

Q: Under which of the following conditions would one mole of He have the highest entropy, S? A) 17C and 15 L B) 127C and 15 L C) 17C and 25 L D) 127C and 25 L

Q: Predict the sign of S for each of the following systems, which occur at constant temperatureI. The volume of 2.0 moles of O2(g) increases from 44 L to 52 L.II. The pressure of 2.0 moles of O2(g) increases from 1.0 atm to 1.2 atm.A) I: S = negative; II: S = negativeB) I: S = negative; II: S = positiveC) I: S = positive; II: S = negativeD) I: S = positive; II: S = positive

Q: What is the entropy change associated with the expansion of one mole of an ideal gas from an initial volume of V to a final volume of 4.50V at constant temperature?A) S = 4.50 R ln (Vf/Vi)B) S = - 4.50 R ln (Vf/Vi)C) S = R ln 4.50D) S = -R ln 4.50

Q: The entropy change associated with the expansion of one mole of an ideal gas from an initial volume of Vi to a final volume of Vf at constant temperature is given by the equation, S = R ln (Vf/Vi). What is the entropy change associated with the expansion of three moles of an ideal gas from an initial volume of Vi to a final volume of Vf at constant temperature?A) S = R ln (Vf/Vi)B) S = 3 mol R ln (Vf/Vi)C) S = R ln (Vf 23/Vi)D) S = R ln (Vf 3!/Vi)

Q: The following pictures represent three equilibrium mixtures for the interconversion of A, B, and C molecules (unshaded spheres) into X, Y, and Z molecules (shaded spheres), respectively. What is the sign of G for each of the three reactions?A) G (1) = -; G (2) = +; G (3) = 0B) G (1) = -; G (2) = 0; G (3) = +C) G (1) = 0; G (2) = -; G (3) = +D) G (1) = +; G (2) = 0; G (3) = -

Q: According to the diagram above,A) G is positive and is equal to a - b.B) G is positive and is equal to b - c.C)G is negative and is equal to b - c.D) G is negative and is equal to a - c.

Q: According to the diagram above,A) G is positive and the equilibrium composition is rich in products.B) G is positive and the equilibrium composition is rich in reactants.C) G is negative and the equilibrium composition is rich in products.D) G is negative and the equilibrium composition is rich is reactants.

Q: According to the diagram above, the forward reaction is A) nonspontaneous at d and e, and spontaneous at f. B) nonspontaneous at d, at equilibrium at e, and spontaneous at f. C) spontaneous at d, at equilibrium at e, and nonspontaneous at f. D) spontaneous at d, e, and f.

Q: Which of the above reaction mixtures is G of reaction = G ?A) (1)B) (2)C) (3)D) (4)

Q: Which of the above reaction mixtures has the most spontaneous forward reaction? A) (1) B) (2) C) (3) D) (4)

Q: Which of the above reaction mixtures has the least spontaneous forward reaction? A) (1) B) (2) C) (3) D) (4)

Q: What are the signs (+ or -) of H, S, and G when the system spontaneously goes from initial state 2 to the equilibrium state?A) H = +, S = +, G = +B) H = +, S = +, G = -C) H = -, S = -, G = +D)H = -, S = -, G = -

Q: What are the signs (+ or -) of H, S, and G when the system spontaneously goes from initial state 1 to the equilibrium state?A) H = +, S = +, G = +B) H = +, S = +, G = -C) H = -, S = -, G = +D) H = -, S = -, G = -

Q: For initial state 2 what is the relationship between the reaction quotient, Qp, and the equilibrium constant, Kp?A) Qp < KpB) Qp = Kp = 1C) Qp = Kp 1D) Qp > Kp

Q: For initial state 1 what is the relationship between the reaction quotient, Qp, and the equilibrium constant, Kp?A) Qp < KpB) Qp = Kp = 1C) Qp = Kp 1D) Qp > Kp

Q: How will the spontaneity of this reaction vary with temperature? This reaction is A) nonspontaneous at all temperatures. B) nonspontaneous at high temperatures and spontaneous at low temperatures. C) spontaneous at high temperatures and nonspontaneous at low temperatures. D) spontaneous at all temperatures.

Q: What are the signs (+, or -) of H, S, and G for this process?A) H = +, S = +, G = +B) H = +, S = +, G = -C) H = -, S = -, G = +D) H = -, S = -,G = -

Q: The figure above represents the reaction O2(g) -> 2O(g), which is nonspontaneous at 25C. How will the spontaneity of this reaction vary with temperature? This reaction isA) nonspontaneous at all temperatures.B) nonspontaneous at high temperatures and spontaneous at low temperatures.C) spontaneous at high temperatures and nonspontaneous at low temperatures.D) spontaneous at all temperatures.

Q: The figure above represents the nonspontaneous reaction O2(g) -> 2O(g). What are the signs (+ or -) of H, S, and G for this process?A) H = +, S = +, G = +B) H = +, S = +, G = -C) H = -, S = -, G = +D) H = -, S = -, G = -

Q: An ideal gas is expanded at constant temperature. What are the signs (+, -, or 0) of H, S, and G for this system?A) H = +, S = -, G = +B) H = 0, S = +, G = -C) H = 0, S = -, G = +D) H = -, S = +, G = -

Q: The figure represents the spontaneous evaporation of nitrogen in which liquid nitrogen, N2(l), becomes gaseous nitrogen, N2(g): N2(l) -> N2(g). What are the signs (+ or -) of H, S, and G for this process?A) H = +, S = +,G = +B) H = +, S = +, G = -C) H = -, S = -, G = +D) H = -, S = -, G = -

Q: The figure represents the spontaneous deposition of iodine in which iodine vapor, I2(g), becomes crystalline iodine solid I2(s): I2(g): -> I2(s). What are the signs (+ or -) of H, S, and G for this process?A) H = +, S = +, G = +B) H = +, S = +, G = -C) H = -, S = -, G = +D) H = -, S = -, G = -

Q: In figure (1) below oxygen molecules, represented by unshaded spheres, and chlorine molecules, represented by shaded spheres, are in separate compartments. Figure (2) shows the equilibrium state of the system after the stopcock separating the two compartments is opened. Assuming the oxygen and the chlorine behave as ideal gases, what are the signs (+, -, or 0) of H, S, and G for this process?A) H = +, S = -, G = +B) H = 0, S = +, G = -C) H = 0, S = -, G = +D) H = -, S = +, G = -

Q: In figure (1) below argon atoms, represented by unshaded spheres, and neon atoms, represented by shaded spheres, are in separate compartments. Figure (2) shows the equilibrium state of the system after the stopcock separating the two compartments is opened. Assuming that argon and neon behave as ideal gases, what are the signs (+, -, or 0) of H, S, and G for this process?A) H = +, S = -, G = +B) H = 0, S = +, G = -C) H = 0, S = -, G = +D) H = -, S = +, G = -

Q: If ΔG is small and positive, A) the forward reaction is spontaneous and the system is far from equilibrium. B) the forward reaction is spontaneous and the system is near equilibrium. C) the reverse reaction is spontaneous and the system is far from equilibrium. D) the reverse reaction is spontaneous and the system is near equilibrium.

Q: For the following reaction find Kp at 25C and indicate whether Kp should increase or decrease as the temperature rises.NH4HS(s) H2S(g) + NH3(g) H = 83.47 kJ and G = 17.5 kJ at 25C.A) Kp = 8.6 10-4 and Kp should increase as the temperature rises.B) Kp = 8.6 10-4 and Kp should decrease as the temperature rises.C) Kp = 1.2 103 and Kp should increase as the temperature rises.D) Kp = 1.2 103 and Kp should decrease as the temperature rises.

Q: If G is positive for a reaction,A) K < 0.B) K = 0.C) K is between 0 and 1.D) K > 1.

Q: If G is negative for a reaction,A) K < 0.B) K = 0.C) K is between 0 and 1.D) K > 1.

Q: What is K if G = -18.0 kJ for a reaction at 25?A) 1.4 103B) 1.2 102C) 8.1 10-3D) 7.3 10-4

Q: Solid NaHCO3 is heated to 90C. At equilibrium the total pressure of the gases produced is 0.545 atm. Calculate G at 90C for the reaction2 NaHCO3(s) Na2CO3(s) + H2O(g) + CO2(g).A) -7.85 kJB) -3.67 kJC) +3.67 kJD) +7.85 kJ

Q: At high temperatures, boron carbide vaporizes according toB4C(s) 4 B(g) + C(s)At 2500 K, the equilibrium pressure of B(g) is 0.0342 mm Hg over a mixture of 0.300 mol B4C(s) and 0.500 mol C(s). Calculate G for this process.A) 832 kJB) 799 kJC) 281 kJD) 247 kJ

Q: Calculate Ksp for PbI2 at 25C based on the following data: A) 4 10-31 B) 8 10-18 C) 9 10-9 D) 5 10-5

Q: When equilibrium is reached at constant temperature and pressure,A) Q = 1.B) G = 0.C) S is maximized.D) G is minimized.

Q: What is the relationship between G, Qp, and Kp for a reaction involving gases?A) G = Qp/KpB) G = Kp/QpC) G = RTln(Qp/Kp)D) G = RTln(Kp/Qp)

Q: If Q increasesA) G increases and the reaction becomes more spontaneous.B) G increases and the reaction becomes less spontaneous.C) G decreases and the reaction becomes more spontaneous.D) G decreases and the reaction becomes less spontaneous.

Q: What is the relationship between G and the GF for the reaction below?MgF2(s) Mg2+(aq) + 2 F-(aq)A) G = {Gf [Mg2+ (aq)] + 2 Gf [F- (aq)] - Gf [MgF2 (s)]} + RT ln ([Mg2+] [F-]2/[MgF2])B) G = {Gf [Mg2+ (aq)] + 2 Gf [F- (aq)] - Gf [MgF2 (s)]} + RT ln ([Mg2+] [F-])2)C) G = {Gf [Mg2+ (aq)] + 2 Gf [F- (aq)]} + RT ln ([Mg2+] [F-]2)D) G = {Gf [Mg2+ (aq)] + 2 Gf [F- (aq)] - Gf [MgF2 (s)]} + RT ln Ksp

Q: G = G for a reactionA) if Q = K.B) if Q = 1.C) at STP.D) at the start of the reaction.

Q: At 2600 K, G = 775 kJ for the vaporization of boron carbide:B4C(s) 4 B(g) + C(s)Find G and determine if the process is spontaneous if the reaction vessel contains 4.00 mol B4C(s), 0.400 mol of C(s), and B(g) at a partial pressure of 1.0 10-5 atm. At this temperature, R T = 21.6 kJ.A) G = -270 kJ; spontaneous.B) G = -270 kJ; nonspontaneous.C) G = -220 kJ; spontaneous.D)G = -220 kJ; nonspontaneous.

Q: At high temperatures boron carbide vaporizes according to the equationB4C(s) 4 B(g) + C(s)Which equation describes the relationship between G and G for this reaction?A) G = G + R T ln (pB [C]/[B4C])B) G = G + R T ln pBC) G = G + 4 R T ln pBD) G = G - 4 R T ln pB

Q: For a reaction at constant temperature, as Q increasesA) G and G increase.B) G and G decrease.C) G increases, but G remains constant.D) G decreases, but G remains constant.

Q: At 25C, G = -198 kJ for the reaction, NO(g) + O3(g) NO2(g) + O2(g).Calculate G under the following conditions:A) -159 kJB) -167 kJC) -198 kJD) -236 kJ

Q: In general, as a reaction goes to equilibriumA) G decreases.B) Gf decreases.C) G goes to zero.D) G decreases.

Q: Which of the following are unstable with respect to their constituent elements at 25C? A) C8H18(l), CH3OH(l) B) C8H18(l), C2H2(g) C) C2H2(g) D) CH3OH(l)

Q: At 25C, Gf is -620 kJ/mol for SiCl4(g) and -592 kJ/mol for MgCl2(s). Calculate G for the reaction, SiCl4(g) + 2 MG(s) -> 2 MgCl2(s) + Si(s) and determine if the reaction is spontaneous at 25C if the pressure of SiCl4(g) is 1 atm.A) G = 28 kJ; the process is spontaneous.B) G = 28 kJ; the process is nonspontaneous.C) G = -564 kJ; the process is spontaneous.D) G = -564 kJ; the process is nonspontaneous.

Q: A positive value of Gf for a solid compound at 25C means theA) compound cannot exist at 25C and 1 atm.B) compound must be a liquid or a gas at 25C and 1 atm.C) process of forming the compound from the elements is exothermic.D) process of forming the compound from the stable elements at 25C and 1 atm is nonspontaneous.

Q: Which of the following is zero at 25C?A) Gf for N2(g)B) Gf for H2O (l)C) S for N2 (g)D) S for H2O (l)

Q: Which is the lowest at 25C?A) Gf for H2O (s)B) Gf for H2O (l)C) Gf for H2O (g)D) 1/2Gf for O2 (g) plus Gf for H2O (g)

Q: Calculate the standard free energy for the reaction given.2 CH3OH(l) + 3 O2(g) -> 2 CO2(g) + 4 H2O(l)A) -465.2 kJB) -797.8 kJC) -1404.8 kJD) -2069.8 kJ

Q: Which statement is true concerning the standard states of F2(g) and C6H12O6(aq)? A) The standard state for F2(g) is the pure gas at 1 atm and for C6H12O6(aq) is the pure solid at 1 atm. B) The standard state for F2(g) is the pure gas at 1 mol/L and for C6H12O6(aq) is the pure solid at 1 atm. C) The standard state for F2(g) is the pure gas at 1 atm and for C6H12O6(aq) is the solution at a concentration of 1 mol/L. D) The standard state for F2(g) is the pure gas at 1 mol/L and for C6H12O6(aq) is the solution at a concentration of 1 mol/L.

Q: Which of the following is true?A) As a reaction at constant temperature and pressure goes to equilibrium, |G| decreases.B) The larger G, the faster the reaction.C) The standard state for solutes is the pure solute at 1 atm.D) When a reaction reaches equilibrium, G = 0.

Q: For any thermodynamic function Y, Y for a reaction refers to the change in Y for the process in whichA) the mixed reactants at 1 atm go to equilibrium at 1 atm.B) the separate reactants at 1 atm go to equilibrium at 1 atm.C) the separate reactants in their standard states are completely converted to separate products in their standard states.D) the spontaneous reaction occurs.

Q: Calculate the standard free energy change at 25C for the reaction2 NO(g) + O2(g) -> 2 NO2(g).A) -4.7 kJB) -72.6 kJC) -157.8 kJD) -532.6 kJ

Q: A reaction has H = -60.9 kJ/mol and S = 266.6 J/K. Is this reaction spontaneous or nonspontaneous? At what temperature (if any) can the spontaneity be reversed?A) nonspontaneous, can be made spontaneous at 228 KB) nonspontaneous, cannot be made spontaneous at any temperatureC) spontaneous, can be made nonspontaneous at 228 KD) spontaneous, cannot be made nonspontaneous at any temperature

Q: A reaction has H = 61.9 kJ/mol and S = 405.4 J/K. Is this reaction spontaneous or nonspontaneous? At what temperature (if any) can the spontaneity be reversed?A) nonspontaneous, can be made spontaneous at 153 KB) nonspontaneous, cannot be made spontaneous at any temperatureC) spontaneous, can be made nonspontaneous at 153 KD) spontaneous, cannot be made nonspontaneous at any temperature

Q: For the reaction below G = +33.0 kJ, H = +92.2 kJ, and S = +198.7 J/K. Estimate the temperature at which this reaction becomes spontaneous.2 NH3(g) -> N2(g) + 3 H2(g)A) 0.464 KB) 166 KC) 298 KD) 464 K

Q: For the evaporation of water during perspiration on a hot, dry day,A) H is positive and TS = H.B) H is positive and TS > H.C) H is positive and TS < H.D) H is negative and TS is positive.

Q: The signs of G, H, and S at 25C are shown below for three reactions.Which reaction could go in the reverse direction at high temperature?A) IB) IIC) IIID) I and II

Q: Which statement is true about the formation of CaCO3(s) from CaO(s) and CO2(g) at 1.00 atm?CaO(s) + CO2(g) -> CaCO3(s) H = -178.7 kJ and S = -150.4 J/KA) The reaction is spontaneous at all temperatures.B) The reaction is spontaneous at high temperatures.C) The reaction is spontaneous at low temperatures.D) The reaction is not spontaneous at any temperature.

Q: Consider the reaction:N2(g) + 3 F2(g) -> 2 NF3(g) H = -249 kJ and S = -278 J/K at 25CCalculate G and state whether the equilibrium composition should favor reactants or products at standard conditions.A) G = -332 kJ; the equilibrium composition should favor products.B) G = -332 kJ; the equilibrium composition should favor reactants.C) G = -166 kJ; the equilibrium composition should favor products.D) G = -166 kJ; the equilibrium composition should favor reactants.

Q: For bromine, Hvap = 30.91 kJ/mol and Svap = 93.23 JK-1mol-1 at 25C. What is the normal boiling point for bromine?A) 25CB) 58CC) 124CD) 332C

Q: At 25C, H = 1.895 kJ and S = -3.363 J/K for the transitionC(graphite) -> C(diamond)Based on these data,A) graphite cannot be converted to diamond at 1 atm pressure.B) diamond is more stable than graphite at all temperatures at 1 atm.C) diamond is more stable than graphite below 290C and graphite is more stable than diamond above 290C.D) graphite is more stable than diamond below 290C and diamond is more stable than graphite above 290C.

Q: The solubility of manganese(II) fluoride in water is 6.6 g/mL at 40C and 4.8 g/L at 100C. Based on these data, what is the sign of H and S for the process below?MnF2(s) Mn2+(aq) + 2 F-(aq)A) H is negative but the sign of S cannot be determined from this information.B) H is negative and S is definitely negative.C) H is positive but the sign of S cannot be determined from this information.D) H is positive and S is definitely negative.

Q: For a particular process, G = H at a given temperature and pressure. Therefore,A) S is positive if H is positive and negative is H is negative.B) S is negative if H is positive and positive if H is negative.C) S is zero.D) S = G/T.

Q: For a particular process G is less than H. ThereforeA) S is positive.B) S is negative.C) S is zero.D) S is negative if H is positive and S is positive if H is negative.

Q: For the reaction 3 C2H2(g) -> C6H6(l) at 25C, the standard enthalpy change is -631 kJ and the standard entropy change is -430 J/K. Calculate the standard free energy change at 25C.A) 948 kJB) -503 kJC) -618 kJD) -1061 kJ

Q: Other than only PV work, what reaction conditions must be satisfied for the sign of G to be used as a criterion for spontaneity?A) constant volume and pressureB) constant temperature and pressureC) constant temperature and volumeD) constant volume only

Q: Why is the sign of G rather than the sign of Stotal generally used to determine the spontaneity of a chemical reaction?A) G can be used for processes that occur under any conditions.B) G involves thermodynamic functions of the system only.C) Free energy is easier to understand than entropy.D) Entropy is based on probability and is therefore less reliable.

Q: At constant pressure and temperature, which statement is true?A) All reactions for which H < 0 are spontaneous.B) All reactions for which S < 0 are spontaneous.C) All reactions for which G < 0 are spontaneous.D) All reactions for which K < 1 are spontaneous.

Q: A hot penny is dropped into cold water inside a polystyrene foam cup. Assuming negligible heat loss to the atmosphere and the cup,

Q: During perspiration, A) the entropy of the water evaporated decreases and the entropy of the body decreases. B) the entropy of the water evaporated decreases and the entropy of the body increases. C) the entropy of the water evaporated increases and the entropy of the body decreases. D) the entropy of the water evaporated increases and the entropy of the body increases.

Q: For the processCaCO3(calcite) -> CaCO3(aragonite) H = -0.21 kJ, S = -4.2 J/KAssuming that the surroundings can be considered a large heat reservoir at 25C, calculate Ssurr and Stotal for the process at 25C and 1 atm pressure. Is the process spontaneous at 25C and 1 atm pressure?A) Ssurr = 4.2 J/K, total = 0, not spontaneousB) Ssurr = 0.7 J/K, Stotal = -3.5 J/K, not spontaneousC) Ssurr = -0.7 J/K, Stotal = -4.9 J/K, spontaneousD) Ssurr = -0.7 J/K, Stotal = -4.9 J/K, not spontaneous

Q: For a spontaneous process A) energy and entropy are conserved. B) energy is conserved and the entropy of the system and surroundings increases. C) the energy of the system and the surroundings decreases and the entropy of the system and surroundings increases. D) both the energy and the entropy of the system and surroundings decrease.

Q: For a process to be at equilibrium, it is necessary thatA) Ssys = Ssurr.B) Ssys = -Ssurr.C) Ssys = 0.D) Ssys = 0 and Ssurr = 0.

Q: According to the second law of thermodynamics, all reactions proceed spontaneously in the direction that increases the entropy of theA) surroundings.B) system.C) system - surroundingsD) system + surroundings

Q: Which of the following is a criterion for spontaneity that holds for any process?A) G < 0B) G > 0C) Stotal < 0D) Stotal > 0

Q: Which of the three laws of thermodynamics provides a criterion for spontaneity? A) the first law of thermodynamics B) the second law of thermodynamics C) the third law of thermodynamics D) both the second and third laws of thermodynamics