Thermodynamics ...

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 :

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

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.

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.

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

Statement–1 : The enthalpy of formation of H₂O(l) is greater than of H₂O (g).
Statement–2: Enthalpy change is negative for the condensation reaction H₂O (g) → H₂O(l)

Statement–1 : Heat of neutralisation of perchloric acid, HClO₃, with NaOH is same as that of HCl with NaOH.
Statement–2: Both HCl and HClO₄ are strong acids.

Statement–1 : When a gas at high pressure expands against vacuum, the work done is maximum.
Statement–2: Work done in expansion depends upon the pressure inside the gas and increase