Chemical Thermodynamics — practice questions

174 curated practice questions from Chemical Thermodynamics (Chemistry JEE Main, NTA Exams) — 31 medium, 134 easy, 9 hard. Every question includes the final answer free; step-by-step worked solutions with a free account.

• Given below are two statements Statement I : Internal energy of a gas doesn't change in an adiabatic process. Statement…
• Identify the correct statement regarding a spontaneous process.
• Calculate the heat of the reaction CH 2 = CH 2 (g) + H 2 (g) → CH 3 CH 3 (g) given that bond energy of C – C, C = C, C…
• Match List-I with List-II. array |l|l| List-I & List-II (A) Spontaneous process & (I) H array |l|l| & array l molecules…
• The enthalpy of neutralisation of HCl by NaOH is –57.1 kJ and that of HCN by NaOH is –12.1 kJ mol –1 . The enthalpy of…
• The enthalpy change for the reaction, H _ 2 O ( ~s ) H _ 2 O ( ) is called
• Given below are two statements. One is labelled as Assertion and the other is labelled as Reason. Assertion: Entropy of…
• Which of the following pairs has heat of neutralisation equal to –57.1 kJ ?
• When one mole of an ideal gas is compressed to half of its initial volume and simultaneously heated to twice its…
• A tightly closed thermoflask contains some ice cubes. This constitutes
• 1 mole of NH 3 gas at 27°C is expanded in reversible adiabatic condition to make volume 8 times (γ = 1.33). Final…
• For the reaction, 2 H _ 2 O ( ~g ) 2 H _ 2 ( ~g )+ O _ 2 ( ~g ) ∆H = 571.6 KJ _ f H ^ of water is :
• The dissociation energy of CH 4 and C 2 H 6 are respectively 360 and 620 kcal/mole. The bond energy of C–C is
• Which of the following neutralisation reactions is most exothermic ?
• An ideal gas is taken around the cycle ABCA as shown in P-V diagram The net work done by the gas during the cycle is…
• When two mole of an ideal gas (C_ p, m . = 5 2 R ) heated from 300 K to 600 K constant pressure. The change in entropy…
• Given below are two statements. One is labelled as Assertion and the other is labelled as Reason. STATEMENT-1…
• For silver, C p (JK -1 mol -1 ) = 23 + 0.01 T. If the temperature (T) of 3 moles of silver is raised from 30 K to 1000…
• The enthalpy of combustion of methane at 25°C is 890 kJ. The heat liberated when 3.2 g of methane is burnt in air is:
• If CH 3 COOH + OH – ⟶ CH 3 COO – + H 2 O + x kJ H + + OH – ⟶ H 2 O + y kJ The enthalpy change for the reaction : CH 3…
• At 25°C and 1 atm pressure, the enthalpy of combustion of benzene (l) and acetylene (g) are –3268 kJ mol –1 and –1300…
• What is the change in internal energy when a gas contracts from 377 mL to 177 mL under a constant pressure of 1520…
• The enthalpy changes at 25°C in successive breaking of O–H bonds of water are : H 2 O(g) ⟶ H(g) + OH(g) ∆H = 498 kJ mol…
• The internal energy change in a system that has absorbed 2 kcal of heat and done 500 J of work is
• For which of the following reactions, ∆H is greater than ∆U ?
• Which of the following relations are correct? (A) U=q+p V (B) G= H-T S (C) S= q_ r v T (D) H= U- n R T Choose the most…
• The enthalpy change for the reaction, C 2 H 6 (g) → 2C(g) + 6H(g) is X kJ. The bond energy of C–H bond is:
• The difference between ∆H and ∆E on a molar basis for the combustion of methane gas at 300K (kelvin) would be :
• Given below are two statements Statement I : Internal energy is a microscopic state variable. Statement II : Internal…
• For the reaction : C _ 2 H _ 4 ( ~g )+3 O _ 2 ( ~g ) 2 CO _ 2 ( ~g )+2 H _ 2 O ( ) at 298 K, ∆U = – 1415 kJ. If R =…
• Which of the following compounds will absorb maximum quantity of heat when dissolved in the same amount of water. The…
• For a reversible process at equilibrium, the change in entropy may be expressed as:
• Given below are two statements. One is labelled as Assertion and the other is labelled as Reason. STATEMENT-1…
• The maximum work obtained by an isothermal reversible expansion of 1 mole of an ideal gas at 27°C from 2.24 to 22.4 L…
• A solution of 200 mL of 1 M KOH is added to 200 mL of 1 M HCl and the mixture after attaining reaction equilibrium…
• A heat engine carries one mole of an ideal mono-atomic gas around the cycle as shown in figure, the amount of heat…
• The correct order of bond enthalpy ( (k J m o l^ -1 ) is : (Jee Main 2023)
• The work done by a weightless piston in causing an expansion ∆V (at constant temperature), when the opposing pressure P…
• An ideal gas is taken through the cycle A → B → C → A as shown in fig. If the net heat supplied to the gas in cycle is…
• Given below are two statements. One is labelled as Assertion and the other is labelled as Reason. STATEMENT-1…
• An ideal gas is allowed to expand form 1 L to 10 L against a constant external pressure of I bar. The work done in kJ…
• The standard heat of formation at 101.3 kNm –2 and 298 K is arbitrarily taken to be zero for :
• Which of the following salts will have maximum cooling effect when 0.5 mole of the salt is dissolved in same amount of…
• Based on the values of B.E. given, ∆ f H o of N 2 H 4 (g) is: Given: N–N = 159 kJ mol –1 ; H–H = 436 kJ mol –1 N N =…
• In an irreversible process taking place at constant T and P and in which only pressure-volume work is being done, the…
• Given : H 2 (g) + ½O 2 (g) → H 2 O(g) + q 1 H 2 (g) + ½O 2 (g) → H 2 O ( l ) + q 2 The enthalpy of vaporisation of…
• In the thermodynamic sense of the word, an irreversible process
• For an endothermic reaction, ∆S is positive. The reaction is :
• Two mole of a monoatomic ideal gas is expanded irreversibly and isothermally at T Kelvin until its volume is doubled…
• For a particular process q = –10 kJ and w=25 kJ. Which of the following statements is true?
• At standard conditions, if the change in the enthalpy for the following reaction is -109 kJ mol -1 H _ 2[a] + Br _ 2[a]…
• The standard enthalpies of formation of HCl(g), H(g) and Cl(g) are –92.2, 217.7 and 121.4 kJ mol –1 respectively. The…
• In a reversible reaction of the type A + B ⇌ AB, in general:
• In a given process of an ideal gas, dw = 0 and dq < 0. Then, for the gas:
• Ice–Water mass ratio is maintained as 1 : 1 in a given system containing water in equilibrium with ice at constant…
• One mole of an ideal diatomic gas (C v = 5 cal) was transformed from initial 25°C and 1 L to the state when temperature…
• A reaction has ∆H = – 33 kJ and ∆S = +58 J/K. This reaction would be :
• Warming ammonium chloride with sodium hydroxide in a test tube is an example of :
• The enthalpies of solution of anhydrous CuSO 4 and CuSO 4 .5H 2 O are –15.89 and 2.80 k cal mol –1 respectively. The…
• For the reaction, PCl _ 5 ( ~g ) PCl _ 3 ( ~g )+ Cl _ 2 ( ~g )
• Calculate the heat required to make 6.4 Kg CaC 2 from CaO(s) and C(s) from the reaction : CaO(s) + 3 C(s) → CaC 2 (s) +…
• Two moles of an ideal gas undergoes isothermal reversible expansion from 2 L to 8 L at 300K. The enthalpy change of the…
• In the reaction : CO _ 2 ( ~g )+ H _ 2 ( ~g ) CO ( ~g )+ H _ 2 O ( ~g ) ∆H = 2.8 kJ then ∆H represents
• What happens when methane undergoes combustion in systems A and B respectively? (Jee Main 2023)
• The products of combustion of an aliphatic thiol, (RSH) at 298 K are:
• Given below are two statements. One is labelled as Assertion and the other is labelled as Reason. STATEMENT-1…
• Heat of neutralization of four monobasic acids A, B, C and D are -13.7, -9.4, -11.2 and -12.4 kcal/mol respectively…
• Given (A) 2 CO (g)+ O _ 2 (g) 2 CO _ 2 (g) H_ 1 ^ =-x ~kJ ~mol ^ -1 (B) C(graphite) + O _ 2 ( ~g ) CO ( ~g ) . H _ 2 ^…
• Given below are two statements. One is labelled as Assertion and the other is labelled as Reason. STATEMENT - 1…
• Vapour pressure and temperature relationship is shown as, log P= -500[K] T +15 . Heat of vaporisation will be:
• The enthalpies of elements in their standard states are taken as zero. Hence the enthalpy of formation of a compound
• A sample of liquid in a thermally insulated container (a calorimeter) is stirred for 2 hr by a mechanical linkage to a…
• For the reaction: array l X _ 2 O _ 4 (t) 2 XO _ 2 ( ~g ) U=2.1 k cal , S=20 cal ~K ^ -1 at 300 ~K array Hence G is:
• 10 mole of ideal gas expand isothermally and reversibly from a pressure of 10 atm to 1 atm at 300 K. What is the…
• The enthalpies of formation of N 2 O and NO at 298 K are 82 and 90 kJ mol –1 . The enthalpy of the reaction : N _ 2 O (…
• Water is boiled under a pressure of 1.0 atm. When an electric current of 0.50 A from a 12V supply is passed for 300 s…
• A given mass of gas expands from the state A to the state B by three paths 1, 2 and 3 as shown in the figure. If w 1 …
• (∆U – ∆H) for the following equation is N 2 + 3H 2 → 2NH 3 .
• Given below are two statements. One is labelled as Assertion and the other is labelled as Reason. STATEMENT-1…
• In which of the following cases, the reaction is spontaneous at all temperatures ?
• What should be the H _ f ^ a of OH ^ - ion, if the standard enthalpy of formation of liquid water is -68.31 kcal and H_…
• The heat of neutralisation of NaOH and HCl is 57.3 kJ mol –1 . The amount of heat liberated when 0.25 mol of H 2 SO 4…
• The standard reaction Gibbs energy for a chemical reaction at an absolute temperature T is given by _ r G =A-B t Where…
• In which of the processes, does the internal energy of the system remains constant?
• For the reaction at 300 K A(g) + B(g) → C(g) ∆U = –3.0 kcal ∆S = –10.0 cal/K (R ≈ 2 cal mol –1 K –1 ) ∆G is :
• If S + O 2 → SO 2 ∆H = –298.2 kJ SO _ 2 + 1 2 O _ 2 SO _ 3 ∆H = –98.2 kJ SO _ 3 + H _ 2 O H _ 2 SO _ 4 ∆H = –130.2 kJ H…
• In the above question calculate ∆S gas if process is carried out at constant volume :
• The standard enthalpy and entropy of vaporization of a liquid are 25 kJ mol -1 and 100 J K -1 mol -1 , respectively…
• When a solid is converted directly into gaseous state, the process is called sublimation. The entropy change during the…
• A sample of gas changes from P 1 , V 1 and T 1 to P 2 , V 2 and T 2 by one path and then back to P 1 , V 1 and T 1 , ∆U…
• When steam condenses to water at 90 o C, the entropy of the system decreases. What must be true if the second law of…
• The statement “A heat engine always loses some of its heat energy to the surroundings.” is an example of which of the…
• Heat cannot flow by itself from a body at lower temperature to a body at higher temperature a statement of consequence…
• For the process : CO 2 (s) → CO 2 (g)
• Two moles of Helium gas undergo a reversible cyclic process as shown in figure. Assuming gas to be ideal. What is the…
• Which of the following processes is not accompanied by increase of entropy ?
• The difference between heat of reaction at constant pressure and constant volume for the reaction: 2C 6 H 6 (l) + 15O 2…
• The heat of formation of Fe 2 O 3 (s) is –824.2 kJ mol –1 . ∆H for the reaction. 2 Fe _ 2 O _ 3 ( ~s ) 4 Fe ( ~s )+3 O…
• Heat of neutralization between HCl and NaOH is -13.7 kcal equiv -1 . Heat of neutralization of H 2 C 2 O 4 (oxalic…
• Which one of the following demonstrates a decrease in entropy?
• The difference between heats of reaction at constant pressure and constant volume for the reaction. 2C 6 H 6 ( l ) +…
• In which of the following neutralisation reaction, the heat of neutralisation will be highest ?
• ∆H for the reaction, SO _ 2 ( ~g )+ 1 2 O _ 2 ( ~g ) SO _ 3 ( ~g ) H =-98.3 ~kJ If the enthalpy of formation of SO 3…
• Calculate the work done when 1 mol of an ideal gas is compressed reversibly from 1 bar to 4 bar at a constant…
• As per the First Law of thermodynamics, which of the following statement would be appropriate :
• Find ΔH at 358 K for the reaction, Fe _ 2 O _ 3 (5)+3 H _ 2 ( ~g ) ZFe (5)+3 H _ 2 O ( l ) Given that, H _ 29: =-33.29…
• The enthalpy of vaporisation of a compound AB at its boiling point (127°C) is 6.4 kJ mol –1 . Its entropy of…
• Given below are two statements. One is labelled as Assertion and the other is labelled as Reason. STATEMENT - 1…
• Which of the following is not a state function of thermodynamic system?
• The entropy change when two moles of ideal monoatomic gas is heated from 200°C to 300°C reversibly and isochorically ?
• Given ∆ r S o = –266 and listed [ S _ m ^ o values] calculate S o for Fe 3 O 4 (s) : 4 Fe _ 3 O _ 4 ( ~s )[ .]+ O _ 2 (…
• The enthalpy of formation of two compounds A and B are –84 kJ and –156 kJ respectively. Which one of the following…
• In what proportion 1 M NaOH and 0.5M H 2 SO 4 are mixed so as to release maximum amount of energy and to form 100 mL…
• The heat of combustion of yellow phosphorus and red phosphorus are - 9.19 and - 8.78 kJ mol -1 respectively, then heat…
• One mole of ice at 0°C and 4.6 mm of Hg is converted to water vapour at a constant temperature and pressure. Find H and…
• At 25°C and 1 atm pressure, the enthalpies of combustion are as given below: Substance H 2 C(graphite) C 2 H 6 (g) A _…
• If the bond dissociation energies of XY, X 2 and Y 2 (all diatomic molecules) are in the ratio of 1 : 1 : 0.5 and ΔH f…
• An ideal gas receives 10 J of heat in a reversible isothermal expansion. Then the magnitude of work done by the gas :
• Molar heat capacity of water in equilibrium with ice at constant pressure is
• The lattice enthalpy and hydration enthalpy of four compounds are given below: array ccc Compound & array c Lattice…
• For the reaction : C _ ( s ) + O _ 2( ~g ) CO _ 2( ~g )
• Two moles of an ideal gas at 2 bar and 27 ° C expand isothermally against a constant pressure of 1 bar. The work done…
• Given below are two statements. One is labelled as Assertion and the other is labelled as Reason. Assertion: Mass and…
• During the adiabatic expansion of an ideal gas against atmospheric pressure, the internal energy will
• Consider the reaction at 300 K H 2 (g) + Cl 2 (g) → 2HCl(g); ∆Hº = –185 kJ If 2 mole of H 2 completely react with 2…
• Heat of formation of a compound is equal in magnitude to its:
• Using the following energy values, determine the lattice energy of KF(s): array ll Property & Energy ( k J ~ m o l ^ -1…
• What is the relation between, ∆H and ∆U in this reaction: CH 4 (g) + 2O 2 (g) → CO 2 (g) + 2H 2 O(l)
• The enthalpy change for the following reaction is 368 kJ. Calculate the average O–F bond energy. OF _ 2 ( ~g ) O ( ~g…
• The entropy change involved in the isothermal reversible expansion of 2 moles of an ideal gas from a volume of 10 dm 3…
• Which of the following reactions represents enthalpy of formation of AgCl ?
• An imaginary reaction X → Y takes place in three steps X → A, ∆H = –q 1 ; B → A, ∆H = –q 2 , B → Y, ∆H = –q 3 If Hess’…
• Enthalpy of sublimation of iodine is 24 cal g -1 at 200°​C. If specific heat of I 2 (s) and I 2 (vap) are 0.055 and…
• The following data is known about the melting of a compound AB. ∆H = 9.2 kJ mol –1 . ∆S = 0.008 kJ K –1 mol –1 . Its…
• Which of the following changes would definitely increase the internal energy of a system?
• The standard enthalpy of formation of NH 3 is - 46.0 kJ mol -1 . If the enthalpy of formation of H 2 from its atoms is…
• One mole of an anhydrous salt AB dissolves in water with the evolution of 21 Jmol -1 of heat. If the heat of hydration…
• When 0.5 g of sulphur is burnt to SO 2 4.6 kJ of heat is liberated. What is the enthalpy of formation of sulphur…
• Which of the following conditions is not favourable for the feasibility of a process ?
• Given below are two statements. One is labelled as Assertion and the other is labelled as Reason. STATEMENT-1…
• Which of the following relation is not correct? (JEE Main 2022)
• The following reaction occurs at 25 o C, 2 NO ( ~g ) [1 10^ -5 ~atm ]+ Cl _ 2 ( ~g ) [1 10^ -2 ~atm ] ⇌ ZNOCl [1 10^ -2…
• Which of the following equations represents standard heat of formation of methane ?
• The enthalpy of neutralisation of NH 4 OH and HCl is :
• The enthalpies of neutralization of a weak base AOH and a strong base BOH by HCl are –12250 cal/mol and –13000 cal/mol…
• Which of the following is true for the reaction ? H 2 O (  ) ⇌ H 2 O (g) at 100°C and 1 atm pressure
• If one mole of an ideal gas ( C _ p . m . = 5 2 R ) is expanded isothermally at 300 K until it’s volume is tripled…
• A system absorb 10 kJ of heat at constant volume and its temperature rises from 27°C to 37°C. The value of ∆U is
• The enthalpies of combustion of carbon and carbon monoxide are - 393.5 and - 283 kJ mol -1 respectively. The enthalpy…
• Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R) Assertion (A)…
• 5 mole of an ideal gas expand isothermally and irreversibly from a pressure of 10 atm to 1 atm against a constant…
• The entropy change for the conversion of 1 mol of α–tin (at 13°C, 1 atm) to 1 mol of β–tin (13°C, 1 atm), if enthalpy…
• The enthalpy of vaporisation of a substance is 8400 J mol –1 and its boiling point is –173ºC. The entropy change for…
• The internal energy change when a system goes from state 'A' to 'B' is 40 kJ mol -1 . If the system goes from 'A' to…
• C(s) + O 2 (g) → CO 2 (g) + 400 kJ C(s) + 1 2 O 2 (g) → CO(g) + 100 kJ When coal of purity 60% is allowed to burn in…
• In a system where ∆E = –51.0 kJ, a piston expanded against a p ext of 1.2 atm giving a change in volume of 32.0 L. What…
• In a given process of an ideal gas, W > 0 and U > 0. From this it can be concluded that
• Calculate the heat of formation of PCl 5 (s) from the following data : 2P(s) + 3Cl 2 (g) ⟶ 2PCl 3 ( l ) ∆H = –151.8…
• Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A)…
• The enthalpies of combustion of rhombic sulphur and monoclinic sulphur are –295.1 and –296.4 kJ mol –1 respectively…
• Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R Assertion A: The…
• The ∆H θ for the reaction, 4S(s) + 6O 2 (g) → 4 SO 3 (g) is –1583.2 kJ. Standard enthalpy of formation of sulphur…
• If mass-energy equivalence is taken into account, when water is cooled to form ice, the mass of water should
• Given below are two statements. One is labelled as Assertion and the other is labelled as Reason. STATEMENT - 1…
• The enthalpy of neutralization of the given reaction H _ 2 SO _ 4 +2 NaOH Na _ 2 SO _ 4 +2 H _ 2 O + y kcal is:
• Which of the following is a state function and also an extensive property?
• The enthalpies of combustion of carbon and carbon monoxide are –393.5 and –283.0 kJ mol –1 respectively. The enthalpy…
• When 1 mole of gas is heated at constant volume, the temperature is raised from 298 to 308 K. Heat supplied to the gas…
• One mole of ice melts at 0°C and 1 atm absorbing 1440 cal of heat. The molar volume of ice and water are 0.0196 and…
• The heat of neutralisation of strong base and strong acid is 57.0 kJ. The heat released when 0.5 mol of HNO 3 is added…
• One mole of an ideal gas expands reversibly and adiabatically from a temperature of 27 o C. If the work done during the…
• Calculate the entropy change (J/mol K) of the given reaction. The molar entropies [J/K–mol] are given in brackets after…
• On combustion, carbon forms two oxides CO and CO 2 . Heat of formation of CO 2 is –393.5 kJ and that of CO is –110.5…
• 2 mole of an ideal gas at 27 o C expands isothermally and reversibly from a volume of 4 litres to 40 litre. The work…

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