Thermodynamics Questions

Which of the following is correct option for free expansion of an ideal gas under adiabatic condition ?

Under the same conditions how many ml of 1 M KOH and 0.5 M H₂SO₄ solutions respectively when mixed for a total volume of 100 ml produce the highest rise in temperature -

1 gm H₂ gas at S.T.P. is expanded so that volume is doubled. Hence work done is -

The lattice enthalpy and hydration enthalpy of four compounds are given below – Compound Lattice enthalpy Hydration enthalpy P +780 −920 Q +1012 −812 R +828 −878 S +632 −600 The pair of compounds which is soluble in water is -

Standard enthalpies of formation of O₃, CO₂, NH₃ and HI are 142.2, −393.2, −46.2 and +25.9 kJ mol⁻¹ respectively. The order of their increasing stabilities will be -

Consider the following reactions at 1000°C - I. Zn(s) + 1/2 O₂(g) → ZnO(s); ΔG° = −360 kJ mol⁻¹ II. C(graphite) + 1/2 O₂(g) → CO(g); ΔG° = −460 kJ mol⁻¹ Choose the correct statement at 1000°C :

The value of ΔH° for the reaction Cu⁺(g) + I⁻(g) → CuI(g) is − 446 kJ mol⁻¹. If the ionization energy of Cu(g) is 745 kJ mol⁻¹ and the electron affinity of I(g) is − 295 kJ mol⁻¹, then the value of ΔH° for the formation of one mole of CuI(g) from Cu(

F₂C = CF−CF = CF₂ ⟶ cyclic product For this reaction (ring closure), ΔH = −49 kJ mol⁻¹, ΔS = −40.2 J K⁻¹ mol⁻¹. Upto what temperature is the forward reaction spontaneous ?

Equal volumes of 1 M HCl and 1 M H₂SO₄ are neutralized by 1 M NaOH solution and x and y kJ/equivalent of heat are liberated respectively. Which of the following relations is correct ?

The enthalpy of combustion at 25°C of H₂, cyclohexane (C₆H₁₂) and cyclohexene (C₆H₁₀) are − 241, −3920 and −3800 kJ/mol respectively. The heat of hydrogenation of cyclohexene is -

When ethyne is passed through a red hot tube, then formation of benzene takes place - ΔHf°(C₂H₂)(g) = 230 kJ mol⁻¹ ΔHf°(C₆H₆)(g) = 85 kJ mol⁻¹ Calculate the standard heat of trimerisation of ethyne to benzene. 3 C₂H₂(g) ⟶ C₆H₆(g)

Under certain conditions, the value of ΔG for a hypothetical reaction, X + Y ⟶ Z is greater than zero, then –

The Bond-energies of C ≡ C, C—H, H—H and C = C are 198, 98, 103, 145 kcal respectively. The enthalpy change of the reaction HC ≡ CH + H₂ ⟶ C₂H₄ is -

The value of ΔHf° of U₃O₈ is −853.5 KJ mol⁻¹. Also ΔH° for the reaction 3 UO₂ + O₂ ⟶ U₃O₈, is −76.00 KJ. The value of ΔHf° of UO₂ is approx –

Which of the following process/es proceed towards more disordered state ? (i) Stretching the rubber band (ii) Sublimation of dry ice (iii) Crystallisation of salt from solution (iv) dissolution of sugar in water

The heat produced by complete neutralisation of 100 ml of HNO₃ with 300 ml of decimolar KOH solution is 1.713 kJ. The molarity of HNO₃ solution will be –

For the chemical reaction A + B ⟶ P + Q two paths are given in the diagram. Which of the following relationship is correct –

The heat of combustion of ethylene C₂H₄(g) is − 1420 kJ/mole. The volume of C₂H₄ at NTP that would evolve 355 kJ on combustion is -

Two moles of an ideal monoatomic gas are allowed to expand adiabatically and reversibly from 300 K to 200 K. The work done in the process is (Cv = 12.5 J/K/mol) -

The standard free energy change ΔG° is related to equilibrium constant, Kp as -

ΔS° and ΔH° for combustion of methane are 186 JK⁻¹ and − 74.8 kJ mol⁻¹ respectively. The value of ΔU° for the process would be -

The bond enthalpies of H₂, X₂ and HX are in the ratio of 2 : 1 : 2. if the enthalpy for formation of HX is − 50 kJ mol⁻¹, the bond enthalpy of H₂ is -

Which of the following process involves decrease in the entropy of system -

The solubility product of AgCl is 1.6 × 10⁻¹⁰ and log ksp is −9.80. The value of ΔG° for the process, AgCl (s) + aq ⇌ Ag⁺ (aq) + Cl⁻ (aq) is -

Latent heat of vaporisation of water is 540 cal g⁻¹. The entropy change during the evaporation of 1 mole of water at 100°C is -

For the reaction, bond energies are given as under – (i) C—C, 346 kJ/mol (ii) C—H, 413 kJ/mol (iii) H—H, 437 kJ/mol and (iv) C=C, 611 kJ/mol What will be the value of ΔH at 25°C for the above reaction ?

Given that CO(g) + O₂(g) ⟶ CO₂(g); ΔH° = − x kJ which of the following is correct –

The enthalpy of neutralization of NH₄OH and CH₃COOH is − 10.5 kcal/mole and enthalpy of neutralization of strong base and CH₃COOH is − 12.5 kcal/mole. Calculate the enthalpy of dissociation of NH₄OH –

A mixture of 2 mole of carbon monoxide gas and one mole of dioxygen gas is enclosed in a vessel and is ignited to convert carbon monoxide into carbon dioxide. If the enthalpy change is ΔH and internal energy change is ΔU, then for the above process –

Given : Heat of ionization of two acids : ΔH° (HCN) = 45.2 kJ mol⁻¹ ΔH° (CH₃COOH) = 2.1 kJ mol⁻¹ which relationship for the two acids is true –

The enthalpies of formation of N₂O and NO are 82 and 90 kJ mol⁻¹, respectively. The enthalpy of the reaction is : 2N₂O(g) + O₂(g) → 4NO(g) would be -

Work done in vaporisation of one mol of water at 373 K against the pressure of 1 atmosphere is approximately -

For the process : NH₃ (g) + HCl (g) → NH₄Cl (s) ; Which one is correct ?

For the process 2F (g) → F₂(g), the sign of ΔH and ΔS respectively are -

For a reversible process -

Enthalpy of neutralisation of NaOH with H₂SO₄ is − 57.3 KJ mole⁻¹ and − 55.2 KJ mol⁻¹ with ethanoic acid. Which of the following is the best explanation of this difference -

The heat change accompanying the reaction 2H₂ (g) + O₂ (g) → 2H₂ O (ℓ) ; Δ H = −136 kcal is called -

The work done by the system in a cyclic process involving one mole of an ideal monoatomic gas is −50 kJ/cycle. The heat absorbed by the system per cycle is -

For a reaction A (g) + 3 B (g) → 2C(g) ; Δ H° = −24 kJ The value of ΔG° is - 9 kJ. The standard entropy change of reaction is :

(i) H₂(g) + Cl₂(g) →2HCl(g) ; Δ H= − x kJ (ii) NaCl + H₂SO₄ → NaHSO₄ +HCl ; Δ H= − y kJ (iii)2H₂O +2Cl₂ →4HCl +O₂ ; Δ H= − z kJ From the above equations, the value of ΔHf of HCl is -

Bond energy of a substance -

N₂(g) + 2O₂(g) → 2NO₂ + X kJ 2NO(g) + O₂(g) → 2NO₂(g) + Y kJ The enthalpy of formation of NO is

The work done by the system in the conversion of 1 mol of water at 100° C and 760 torr to steam is 3.1 KJ. Calculate Δ E for the conversion (Latent heat of vaporisation of water is 40.65 kJ. mol⁻¹)

For a reversible reaction at equilibrium, ΔG is -

The solubility of NaCl in water at 25° C is about 6 moles per litre. Suppose you add 1 mole of NaCl to a litre of water. For the reaction, NaCl + H₂O → Salt solution -

The heat change for the reaction C (s) + 2S (s) → CS₂(ℓ) is called -

If for H₂ (g) + 1/2 O₂ (g) → H₂O (g); Δ H₁ is enthalpy of reaction and for H₂(g) + 1/2 O₂ (g) → H₂O (ℓ) Δ H₂ is enthalpy of reaction. Then magnitude of-

Enthalpy change of the reaction 2H (g) → H₂(g) is − 104 kcal The H - H bond dissociation energy is-

The difference between Δ H and Δ E at constant volume is equal to -

The heat of combustion of ethanol determined in a bomb calorimeter is −670.48 K. cals mol⁻¹ at 25°C. What is ΔE at 25°C for the reaction -