JEE Questions for Chemistry Thermodynamics Quiz 9 - MCQExams.com

C2H6 (g) + 3.5 O2 (g) → 2CO2 (g) + 3H2O (g)
∆Svap (H2O, l) = x1 cal K–1 (boiling point + T1)
∆Hf (H2O, l) = x2
∆Hf (CO2) = x3
∆Hf (C2H6) = x4
Hence DH for the reaction is –
  • 2x3 + 3x2 – x4
  • 2x3 + 3x2 – x4 + 3x1T1
  • 2x3 + 3x2 – x4 – 3x1T1
  • x1T1 + X2 + X3 – x4
C (s) + O2 (g) → CO2 (g); ∆H = –94.3 kcal/mol
CO (g) + O2(g) → CO2 (g); ∆H = – 67.4 kcal/mol
O2(g) → 2O (g); ∆H = 117.4 kcal/mol
CO (g) → C (g) + O(g) ; ∆H = 230.6 kcal/mol
Calculate ∆H for C (s) → C (g) in kcal/mol.
  • 171
  • 154
  • 117
  • 145
The difference between ∆H and ∆E on a molar basis for the combustion of n–octane at 25°C would be : 25ºC
  • – 13.6 kJ
  • – 1.14 kJ
  • – 11.15 kJ
  • + 11.15 kJ
What is the work done against the atmosphere when 25 grams of water vaporizes at 373 K against a constant external pressure of 1 atm ? Assume that steam obeys perfect gas laws. Given that the molar enthalpy of vaporization is 9.72 kcal/mole, what is the change of internal energy in the above process ?
  • 1294.0 cals, 11247 cals
  • 921.4 cals, 11074 cals
  • 1029.4 cals, 12470.6 cals
  • 1129.3 cals, 10207 cals
In the reaction CS2 (l) + 3O2 (g) → CO2 (g) + 2SO2 (g) ∆H = –265 kcal The enthalpies of formation of CO2 and SO2 are both negative and are in the ratio 4 : 3. The enthalpy of formation of CS2 is + 26 kcal/mol. Calculate the enthalpy of formation of SO2.
  • – 90 kcal/mol
  • – 52 kcal/mol
  • – 78 kcal/mol
  • – 71.7 kcal/mol
The bond dissociation energy of gaseous H2, Cl2 and HCl are 104, 58 and 103 kcal mol– 1 respectively. The enthalpy of formation for HCl gas will be
  • – 44.0 kcal
  • – 22.0 kcal
  • 22.0 kcal
  • 44.0 kcal
AB, A2 and B2 are diatomic molecules. If the bond enthalpies of A2, AB & B2 are in the ratio 1 : 1 : 0.5 and enthalpy of formation of AB from A2 and B2 is – 100 kJ/mol–1. What is the bond enthalpy of A2.
  • 400 kJ/mol
  • 200 kJ/mol
  • 100 kJ/mol
  • 300 kJ/mol

Chemistry-Thermodynamics-8906.png
  • 298 K
  • 668 K
  • 966 K
  • ∆G° is +ve, hence the reaction will never be spontaneous
One mole of a gas occupying 3 dm3 expands against constant external pressure of 1 atm to a volume of 13 dm3. The work done is –
  • – 10 atm dm3
  • – 20 atm dm3
  • – 39 atm dm3
  • – 48 atm dm3
The enthalpy change in the oxidation of glucose is – 2880 kJ mol–1. Twenty five per cent of this energy is available for muscular work. If 100 kJ of muscular work is needed to walk one kilometre, then the maximum distance that a person will be able to walk after eating 120 g of glucose will be
  • 4.8 km
  • 2.4 km
  • 8.4 km
  • 9.8 km
The heat of formation of liquid methyl alcohol is kilo joule per mole using the following data will be [Heat of vaporisation of liquid methyl alcohol = 38 kJ/mol. Heat of formation of gaseous atoms from the elements in their standard states : H, 218 kJ/mol; C, 715 kJ/mol; O, 249 kJ/mol. Average bond energies : C – H, 415 kJ/mol; C – O, 356 kJ/mol O – H, 463 kJ/mol.]
  • 46.0 kJ/mole
  • 50.0 kJ/mole
  • 73.3 kJ/mole
  • – 266 kJ/mole
10 g of argon gas is compressed isothermally and reversibly at a temperature of 27°C from 10 L to 5 L. q, W, ∆E and ∆H for this process are [R = 2.0 cal K–1 mo l–1, log10 2 = 0.30. [Atomic wt. of Ar = 40.]
  • W = 106.635 cal, q = 103.635 cal, ∆E ≠ 0 & ∆H = 0
  • W = 53.635 cal, q = – 53.635 cal, ∆E ≠ 0 & ∆H = 0
  • W = – 53.635 cal, q = 63.635 cal, ∆E & ∆H ≠ 0
  • W = 103.635 cal, q = – 103.635 cal, ∆E & ∆H = 0
Molar heat capacity of water in equilibrium with ice at constant pressure is –
  • zero
  • infinity (∞)
  • 40.45 kJ–1 mol–1
  • 75.48 J K–1 mol– 1
Diborane is a potential rocket fuel which undergoes combustion according to the reaction,
B2H6 (g) + 3O2 (g) → B2O3 (s) + 3H2O(g)
from the following data, the enthalpy change for the combustion of diborane will be
2B(s) + O2 (g) → B2O3(s); ∆H = – 1273 kJ
H2(g) + O2 (g) → H2O(l); ∆H = – 286 kJ
H2O(l) → H2O(g) ; ∆H = 44 kJ
2B(s) + 2H2 (g) → B2H6 (g); ∆H = 46 kJ
  • – 2079 kJ mol–1
  • – 1091 kJ mol–1
  • – 2035 kJ mol–1
  • – 762 kJ mol–1
A sample of argon gas at 1 atm pressure and 27°C expands reversibly and adiabatically from 1.25 dm3 to 2.50 dm3. The enthalpy change in this process will be………. [Cv.m. for argon is 12.48 jK–1 mol–1].
  • 114.52 J
  • – 114.52 J
  • – 57.26 J
  • 57.26 J
Find ∆G° and ∆H° for that the reaction CO(g) + O2 (g) → CO2 (g) at 300 K respectively are, when the standard entropy change is – 0.094 kJ mol–1 K–1. The standard Gibbs free energies of formation for CO2 and CO are – 394.4 and – 137.2 kJ mol–1, respectively.
  • ∆G° = 257.2 kJ/mol, DH° = 285.4 kJ/mol
  • ∆G° = 514.4 kJ/mol, DH° = – 570.8 kJ/mol
  • ∆G° = +514.4 kJ/mol, DH° = 570.8 kJ/mol
  • ∆G° = – 257.2 kJ/mol, DH° = – 285.4 kJ/mol
∆H = 30 kJ mol–1, ∆S = 75 J / k / mol. Find boiling temperature at 1 atm.
  • 400 K
  • 300 K
  • 150 K
  • 425 K
There is 1 mol liquid (molar volume 100 ml) in an adiabatic container initial, pressure being 1 bar Now the pressure is steeply increased to 100 bar, and the volume decreased by 1 ml under constant pressure of 100 bar. Calculate ∆H and ∆E. [Given 1 bar = 105 N/m2]
  • ∆E = 0 J, ∆H ≠ 0 J
  • ∆H = 0 J, ∆E = 10 J
  • ∆E = 20 J, ∆H = 890 J
  • ∆E = 0 J, ∆H = 10 J
The ratio of P to V at any instant is constant and is equal to 1, for a monoatomic ideal gas under going a process. What is the molar heat capacity of the gas

  • Chemistry-Thermodynamics-8907.png
  • 2)
    Chemistry-Thermodynamics-8908.png

  • Chemistry-Thermodynamics-8909.png
  • 0
The entropy values (in J K–1 mol–1) of H2 (g) = 130.6 Cl2(g) = 223 and HCl(g) = 186.7 at 298 K and 1 atm pressure are given. Then entropy change for the reaction.
  • + 540.3
  • +727.3
  • – 166.9
  • +19.8
A mixture of 2 mole of CO(g) and one mole of O2 in a closed vessel, is ignited to convert the carbon monoxide to carbon dioxide. If ∆H and ∆U are enthalpy and internal energy change. Then
  • ∆H > ∆U
  • ∆H < ∆U
  • ∆H = ∆U
  • the relationship depends on the capacity of the vessel
For the reaction of one mole zinc dust with one sulphuric acid in a bomb calorimeter, ∆U and w correspond to :
  • ∆U < 0, w = 0
  • ∆U < 0, w < 0
  • ∆U > 0, w = 0
  • ∆U > 0, w > 0
If the enthalpies of formation of Al2O3 and Cr2O3 are – 1596 kJ and – 1134 kJ respectively, then the value of ∆H for the reaction ; 2Al + Cr2O3 → 2Cr + Al2O3 is :
  • – 462 kJ
  • – 1365 kJ
  • – 2530 kJ
  • +2530 kJ
The internal energy change when a system goes from state A to B is 40 kJ/mole. If the system goes from A to B by a reversible path and returns to state A by an irreversible path what would be the net change in internal energy
  • < 40 kJ
  • Zero
  • 40 kJ
  • > 40 kJ
∆G° for the reaction x + y → z is – 4.606 kcal. The value of equilibrium constant of the reaction at 227°C is : (R = 2.0 cal K–1 mol–1 )
  • 100
  • 10
  • 2
  • 0.01
The latent heat of vaporisation of a liquid at 500 K and 1 atm pressure is 10 kcal/mol. What will be the change in internal energy (∆E) of 3 moles of liquid at the same temperature?
  • 13.0 kcal
  • – 13.0 kcal
  • 27.0 kcal
  • – 27.0 kcal
The work done in ergs for a reversible expansion of one mole of an ideal gas from a volume of 10 litres at 25°C is :
  • 3.43 KJ
  • 3.43 Kcal
  • 3.43 J
  • 3.43 cal
Reaction, H2(g) + I2 (g) → 2HI; ∆H = 12.40 kcal. According to this, heat of formation of HI will be
  • 12.40 kcal
  • – 12.4 kcal
  • – 6.20 kcal
  • `6.20 kcal
The heat of combustion of yellow phosphorus and red phosphorus are – 9.91 kJ and – 8.78 kJ respectively. The heat of transition of yellow phosphorus to red phosphorus is :
  • – 18.69 kJ
  • – 67.6 kcal
  • – 120.6 kcal
  • +52.8 kcal
The heat of formation of CO(g) and CO2 (g) are – 26.4 kcal and – 94.0 kcal respectively. The heat of combustion of carbon monoxide will be :
  • + 26.4 kcal
  • – 67.6 kcal
  • – 120.6 kcal
  • +52.8 kcal
The heats of combustion of rhombic and monoclinic sulphur are – 70960 and – 71030 calorie respectively. What will be the heat of conversion of rhombic sulphur to monoclinic sulphur?
  • – 70960 cal
  • – 71030 cal
  • 70 cal
  • – 70 cal
An ideal gas expands in volume from 1 × 10–3 m3 to 1 × 10–2 m3 at 300 K against a constant pressure of 1 × 105 Nm–2 . The work is :
  • – 900 J
  • – 900 kJ
  • 270 kJ
  • + 900 kJ
The enthalpies of combustion of carbon and carbon monoxide are – 393.5 and – 283 kJ mol– 1 respectively. The enthalpy of formation of carbon monoxide per mole is
  • 110.5 kJ
  • 676.5 kJ
  • – 676.5 kJ
  • – 110.5 kJ
If the bond dissociation energies of XY, X2 and Y2 (all diatomic molecules) are in the ratio of 1 : 1 : 0.5 and DHf for the formation of XY is – 200 KJ mol–1. The bond dissociation energy of X2 will be
  • 100 KJ mol–1
  • 200 KJ mol–1
  • 300 KJ mol–1
  • 800 KJ mol–1
Consider the reaction, N2(g) + 3H2(g) 2NH3(g); carried out at constant temperature and pressure. If ∆H and ∆U are enthalpy change and internal energy change respectively, which of the following expressions is true ?
  • ∆H = 0
  • ∆H = ∆U
  • ∆H < ∆U
  • ∆H > ∆U
An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If Ti is the initial temperature and Tf is the final temperature, which of the following statements is correct ?
  • Tf > Ti for reversible process but Tf = Ti for irreversible process
  • (Tf)rev = (Tf)irev
  • Tf = Ti for both reversible and irreversible processes
  • (Tf)rev > (Tf)irev
In conversion of lime–stone to lime, CaCO3(s) → CaO(s) + CO2(g) the values of ∆Ho and ∆So are +179.1 kJ mol–1 and 160.2 J/K respectively at 298 K and 1 bar. Assuming that ∆H° and ∆S° do not change with temperature, temperature above which conversion of limestone to lime will be spontaneous is :
  • 845 K
  • 1118 K
  • 1008 K
  • 1200 K
For a reversible process at T = 300 K, the volume is increased from Vi = 1 L to Vf = 10 L. Calculate ∆H if the process is isothermal
  • 11.47 kJ
  • 4.98 kJ
  • 0
  • – 11.47 kJ
If at 298 K the bond energies of C – H, C – C, C = C and H–H bonds are respectively 414, 347, 615 and 435 kJ mol–1, the value of enthalpy change for the reaction ; H2C = CH2(g) + H2(g) → H3C – CH3(g) at 298 K will be –
  • +125 kJ
  • —125 kJ
  • +250 kJ
  • — 250 kJ
Considering entropy(s) as thermodynamic parameter, the criterion for the spontaneity of any process is :
  • ∆Ssystem + ∆Ssurroundings > 0
  • ∆Ssystem – ∆Ssurroundings > 0
  • ∆Ssystem > 0 only
  • ∆Ssurroundings > 0 only
Assuming that water vapour is an ideal gas, the internal energy change (∆U) when 1 mol of water is vapourisedat 1 bar pressure and 100°C, (Given : Molar enthalpy of vapourization of water at 1 bar and 373 K = 41 kJ mol–1 and R = 8.3 J mol–1 K–will be :
  • 37.904 kJ mol–1
  • 41.00 kJ mol–1
  • 4.100 kJ mol–1
  • 3.7904 mol–1
The standard enthalpy of formation (DHf°) at 398 K for methane, CH4(g) is 74.8 kJ mol–1. The additional information required to determine the average energy for C – H bond formation would be.
  • the dissociation energy of H2 and enthalpy of sublimation of carbon
  • latent heat of vapourisation of methane
  • the first four ionization energies of carbon and electron gain enthalpy of hydrogen
  • the dissociation energy of hydrogen molecule, H2
Standard entropy of X2, Y2 and XY3 are 60, 40 and 50 JK–1 mol–1, respectively. For the reaction,1/2 X2 + 3/2 Y2 → XY3 DH = – 30 kJ. To be at equilibrium the temperature will be :
  • 500 K
  • 750 K
  • 1000 K
  • 1250 K
On the basis of the following thermo chemical data : (∆ƒGºH+ (aq) =H2O(l) → H+ (aq) + OH– (aq.) ; ∆H = 57.32 kJ H2(g) + O2(g) → H2O(l); ∆H = –286.20 kJ The value of enthalpy of formation of OH– ion at 25ºC is :
  • –228.88 kJ
  • +228.88 kJ
  • –343.52 kJ
  • –22.88 kJ
In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is CH3OH(l) + 3/2O2 (g) → CO2(g) + 2H2O(l) At 298 K, standard Gibb’s energies of formation for CH3OH(l), H2O(l) and CO2 (g) are –166.2, –237.2 and –394.4 kJ mol–1 respectively. If standard enthalpy of combustion of methanol is –726kJ mol–1, efficiency of the fuel cell will be :
  • 87%
  • 90%
  • 97%
  • 80%
The standard enthalpy of formation of NH3 is – 46.0 kJ mol–1. If the enthalpy of formation of H2 from its atoms is –436 kJ mol–1 and that of N2 is –712 kJ mol–1, the average bond enthalpy of N – H bond in NH3 is
  • – 964 kJ mol–1
  • + 352 kJ mol–1
  • + 1056 kJ mol–1
  • – 1102 kJ mol–1
For a particular reversible reaction at temperature T, ∆H and ∆S were found to be both +ve. If Te is the temperature at equilibrium, the reaction would be spontaneous when.
  • Te > T
  • T > Te
  • Te is 5 times T
  • T = Te
Choose the correct option about the following sentences [T= True , F =False]
(i) Ice in contact with water constitutes a homogeneous system.
(ii) The process is known as isochoric in which the pressure remains constant throughout the change, i.e., dP = 0.
(iii) A spontaneous process is reversible in nature.
(iv) In an isolated system, one form of energy cannot be converted into another, i.e., internal energy remains constant.
  • FFFF
  • TTTT
  • FTFT
  • FFFT
Choose the correct option about the following sentnences [T= True , F =False]
(i) Molar heat capacity at constant pressure = Molar heat capacity at constant volume + PDV.
(ii) A spontaneous process is accompanied by a decrease in entropy.
(iii) ∆Hsub = DHfusion + DHvap.
(iv) The standard heat of formation represents the formation of the compound from its elements at 25°C and one atmospheric pressure.
(v) Whenever an acid is neutralised by a base, the net reaction is
H+ (aq) + OH– (aq) → H2O(l) ; ∆H = – 13.7 kcal
  • TFTTF
  • TFTTF
  • TFTFTF
  • TFFFF

Chemistry-Thermodynamics-8922.png
  • i – e, ii – a, iii – f, iv – b, v – c, vi – e
  • i – e, ii – a, iii – f, iv – e v – c, vi – d
  • i – e, ii – a, iii – f, iv – b, v – c, vi – d
  • i – e, ii – a, iii – c, iv – b, v – f, vi – d
0:0:1


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