Free Energy and Work Function MCQs

Free energy is the portion of the total energy in a system that is available to do useful work under specific conditions. While the total energy of the system (H) includes some energy that is random and cannot be converted into work, free energy represents the part that can be utilized effectively. Free energy is both a state function and an extensive property. In most thermodynamic processes, neither energy nor entropy remains constant, necessitating the introduction of two new functions that incorporate both energy and entropy. Helmholtz free energy includes elastic and surface energy, with the impact of normal stress being about three orders of magnitude greater than that of elastic energy. Gibbs free energy helps determine the amount of chemical energy a reaction can store or release.

The standard free energy of formation of NO(g) is

(a) 84.8 kJ/mol
(b) 86.8 kJ/mol
(c) 88.8 kJ/mol
(d) 90.8 kJ/mol

Which of the following statements regarding entropy is not true?

(a) S (monoclinic) > S (rhombic)
(b) C (diamond) > C (graphite)
(c) H2O(g) > H2O(l)
(d) O3(g) > O2(g)

If the standard free energy change for a reaction is 1.546 kJ/mol at 500°C, then the value of the standard equilibrium constant for the reaction is

(a) antilog (0.105)
(b) antilog (-0.105)
(c) antilog (0.241)
(d) antilog (-0.241)

Which of the following is an extensive property?

(a) surface area
(b) pressure
(c) molar volume
(d) concentration

During an isothermal expansion of an ideal gas, which of the following is true for the gas?

(a) enthalpy decreases
(b) entropy decreases
(c) enthalpy remains constant
(d) entropy remains constant

Which of the following is expressed to have the largest bond dissociation enthalpy?

(a) HF
(b) HCl
(c) HBr
(d) HI

If one gram of kerosene liberates 46.0 kJ of heat when burned, to what temperature can 0.25 g of kerosene raise the temperature of 75 cm³ of water at 25°C?

(a) 61.6°C
(b) 46.0°C
(c) 66.1°C
(d) 64.0°C

Which of the following is a state function?

(a) q (b) w (c) q_rev/T (d) qw

For a spontaneous process, the change in Gibbs function is equal to the

(a) heat content of the system
(b) entropy change of the system
(c) work of expansion
(d) useful work

The term ( R \ln K_{Po} ) is equal to

(a) – ∆G
(b) – ∆G°
(c) – ∆G/T
(d) – ∆G°/T