21460.The entropy change involved in the isothermal reversible expansion of 2 moles of an ideal gas from a volume of 10 dm3 to a volume of 100 dm3 at 27°C is
42.3 J mol–1 K–1
38.3 J mol–1 K–1
35.8 J mol–1 K–1
32.3 J mol–1 K–1
21461.The Gibbs energy for the decomposition of Al2O3 at 500°C is as follows:
$\dfrac{2}{3}$Al2O3 → $\dfrac{4}{3}$Al + O2, ΔrG = +966 kJ mol–1
The potential difference needed for electrolytic reduction of Al2O3 at 500°C is at least
5.0 V
4.5 V
3.0 V
2.5 V
21462.For the reversible reaction,
A(s) + B(g) ⇌ C(g) + D(g), ΔG° = –350kJ
which one of the following statements is true?
The reaction is thermodynamically non–feasible.
The entropy change is negative.
Equilibrium constant is greater than one.
The reaction should be instantaneous.
21463.If one mole of ammonia and one mole of hydrogen chloride are mixed in a closed container to form ammonium chloride gas, then
ΔH > Δu
ΔH = Δu
ΔH < Δu
there is no relationship
21465.The values of ΔH and ΔS of a certain reaction are –400 kJ mol–1 and –20 kJ mol–1K–1 respectively. The temperature below which the reaction is spontaneous is
100°K
20°C
20°K
120°C
21466.The work done when two mole of an ideal gas is compressed from a volume of 5 m3 to 1 dm3 at 300 K, under a pressure of 100 kPa is
499.9 kJ
–499.9 kJ
–99.5 kJ
42495 kJ
21467.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)irrev > (Tf)rev
Tf > Ti for reversible process but Tf = Ti for irreversible process
(Tf)rev = (Tf)irrev
Tf = Ti for both reversible and irreversible processes
21468.The standard enthalpy of formation (ΔfH°) at 298 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 vaporization of methane
the first four ionization energies of carbon and electron gain enthalpy of hydrogen
the dissociation energy of hydrogen molecule, H2
21469.Based on the first law of thermodynamics, which one of the following is correct?
For an isothermal process, q = +w
For an isochoric process, ΔU = –q
For an adiabatic process, ΔU = –w
For a cyclic process, q = –w
21471.The amount of heat evolved when 500 cm3 of 0.1 M HCl is mixed with 200 cm3 of 0.2 M NaOH is ______.
1.292 kJ
2.292 kJ
3.392 kJ
0.292 kJ
21472.Identify the correct statement from the following in a chemical reaction.
The entropy always increases
The change in entropy along with suitable change in enthalpy decides the fate of a reaction
The enthalpy always decreases
Both the enthalpy and the entropy remain constant
21473.The enthalpy of fusion of water is 1.435 kcal/mol. The molar entropy change for the melting of ice at 0°C is
5.260 cal/(mol K)
0.526 cal/(mol K)
10.52 cal/(mol K)
21.04 cal/(mol K)
21474.The species which by definition has ZERO standard molar enthalpy of formation at 298 K is
Br2(g)
Cl2(g)
H2O(g)
CH4(g)
21475.One mole of which of the following has the highest entropy?
liquid nitrogen
hydrogen gas
mercury
diamond
21476.Consider the reaction :
4NO2(g) + O2(g) ⟶ 2N2O5(g), ΔrH = –111 kJ.
If N2O5(s) is formed instead of N2O5(g) in the above reaction, the ΔrH value will be:
(given, ΔH of sublimation for N2O5 is 54 kJ mol–1)
–219 kJ
–165 kJ
+54 kJ
+219 kJ
21477.For a particular reversible reaction at temperature T, ΔH and ΔS were found to be both +ve. If Te is the temperature at equilibrium, the reaction would be spontaneous when
T = Te
Te > T
T > Te
Te is 5 times T
21478.In a constant volume calorimeter, 3.5 g of a gas with molecular weight 28 was burnt in excess oxygen at 298.0 K. The temperature of the calorimeter was found to increase from 298.0 K to 298.45 K due to the combustion process. Given that the heat capacity of the calorimeter is 2.5 kJ K–1, the numerical value for the enthalpy of combustion of the gas in kJ mol–1 is
3
7
8
9
21479.In which of the following process, a maximum increase in entropy is observed?
dissolution of salt in water
condensation of water
sublimation of naphthalene
melting of ice