Thermodynamics Questions

The enthalpy of the reaction H₂O₂(l) → H₂O(l) + 1/2 O₂(g) − 23.5 kcal mol⁻¹ and the enthalpy of formation of H₂O(l) is − 68.3 kcal mol⁻¹. The enthalpy of formation of H₂O₂(l) is -

The heat of combustion of solid benzoic acid at constant volume is −321.30 kJ at 27°C. The heat of combustion at constant pressure is -

Calculate the bond energy of C-H bond from the following data : (a) C(s) + 2H₂(g) → CH₄(g) ; ΔH = −74.8 KJ (b) H₂(g) → 2H(g) ; ΔH = 435.4 KJ (c) C(s) → C(g) ; ΔH = 718.4 KJ.

How much heat is liberated when 100 mL of 0.1 M NaOH are completely neutralised by 100 mL of 0.1 M HCl -

For an endothermic reaction ΔS is positive. The reaction is -

The heat of neutralisation is constant when dilute solution of -

Heat of neutralisation of HF is -

For a certain reaction the change in enthalpy and change in entropy are 40.63 kJ mol⁻¹ and 100 JK⁻¹ mol⁻¹. What is the value of ΔG at 27°C and indicate whether the reaction is spontaneous or not -

The work done on the system when one mole of an ideal gas at 500 K is compressed isothermally and reversibly to 1/10th of its original volume (R = 2 cal) -

Heat evolved in the reaction H₂ + Cl₂ → 2HCl is 182 KJ. Bond energies H − H =430 KJ/mole, Cl − Cl = 242 KJ/mole. The H − Cl bond energy is-

According to the diagram given below, the value of ΔH for conversion of A to B is -

The enthalpies of combustion of carbon and carbon monoxide are − 390 KJ and −278 KJ respectively. The enthalpy of formation of CO in kJ is -

H₂ + Cl₂ → 2 HCl; ΔH = − 44K. cals. In this reaction heat of formation of 1 mole of HCl in K. cals is -

Heats of combustion of CH₄, C₂H₆ , C₃H₈ , C₈H₁₈ in K. cals mole⁻¹ as − 210.8, − 368.4, − 526.3, −1302.7 respectively. Decide which is better rocket fuel -

The latent heats of fusion in J g⁻¹ of five substances a (mol.mass = 18) ; b (mol. mass = 20) ; c (mol. mass = 30), d (mol. mass = 60) and e (mol. mass = 30) are respectively 80, 45, 90, 45, 45. Which of following pair has same value of ΔHfusion-

Given that ΔHcomb. of cyclopropane is − 4000 kJ mol⁻¹. The amount of cyclopropane that needs to be burnt in oxygen for producing 2 × 10⁵ kJ of heat is -

Latent heat of vaporisation of a liquid at 500 K and 1 atm pressure is 10.00 kcal/mol. What will be the change in internal energy (ΔE) for 3 mol of liquid at same temperature-

X g of ethanal (CH₃CHO) was subjected to combustion in a bomb calorimeter and the heat produced is Y Joules. Then which of following is correct -

The enthalpy of formation for C₂H₄(g), CO₂(g) and H₂O(l) at 25°C and 1 atm pressure be 52, −394 and −286 kJ mol⁻¹ respectively. The enthalpy of combustion of C₂H₄(g) will be -

How many kcal of heat is evolved by the complete neutralisation of one mole sulphuric acid with NaOH -

The heat of combustion of benzene determined in a bomb calorimeter is − 870 K.cal. mol⁻¹ at 298 K. The value of ΔE for the reaction is -

In a change from state A to state B -

A hypothetical reaction , A → 2B, proceeds through following sequence of steps - A → C; ΔH = q₁ C → D; ΔH = q₂ 1/2 D → B; ΔH = q₃ The heat of reaction is :

The occurrence of reaction is impossible if

The heat of formation of water is given by :

For the spontaneity of a reaction , which is true-

For which of the following substances, the standard heat of formation is zero :

An exothermic reaction has a large positive entropy change. The reaction will be -

For the reaction between CO₂ and graphite CO₂(g) + C(s) → 2CO(g) ΔH = + 170.0 kJ and ΔS = 170 JK⁻¹. The reaction is spontaneous at -

The product of combustion of an aliphatic thiol (R SH) at 298 K are :

One mole of an ideal gas at 300 K is expanded isothermally from an initial volume of 1 litre to 10 litres. The ΔE for this process is (R = 2 cal mol⁻¹ K⁻¹) -

Which law of thermodynamics helps in calculating the absolute entropies of various substances at different temperatures -

In any natural process -

Which of the following state function is not zero at standard state -

The total entropy change for a system and its surroundings increases, if the process is

Which law of thermodynamics introduces the concept of entropy ?

A gas is allowed to expand at constant pressure from a volume of 1.0 litre to 10.0 litre against an external pressure of 0.50 atm. If the gas absorbs 250 J of heat from the surroundings, what are the values of q, w and ΔE ? (Given 1 L atm = 101 J)

For the reaction 2SO₂(g) + O₂(g) → 2SO₃(g) the entropy-

If the enthalpy of vapourisation of water is 186.5 J mol⁻¹, the entropy of its vapourisation will be -

Calculate the temperature at which ΔG = − 5.2 kJ mol⁻¹ ΔH = 145.6 kJ mol⁻¹ and ΔS = 216 JK⁻¹ mol⁻¹ for a chemical reaction -

For the process - CO₂(s) → CO₂(g)

The least random state of H₂O is -

For the reversible vapourisation of water at 100° C and 1 atmospheric pressure. ΔG is equal to?

Which of the following has highest entropy -

Which one of the following is correct -

Free energy change of reversible reaction at equilibrium is -

When an egg is hard boiled, there is -

According to Hess's Law the thermal effect of a reaction depends on -

The net heat change in a chemical reaction is same whether it is brought about in two or more different ways in one or several steps. It is known as -

The enthalpy of formation of ammonia is −46.0 kJ mol⁻¹. The enthalpy for the reaction 2N₂(g) + 6H₂(g) → 4NH₃(g) is equal to -