Spontaneity

IMPORTANT

Spontaneity: Overview

This topic covers concepts, such as, Spontaneity, Spontaneous Reactions, Non-spontaneous Reactions, Entropy, Factors Affecting Entropy & Spontaneity in Terms of Entropy Change etc.

Important Questions on Spontaneity

MEDIUM
IMPORTANT

For vaporization of water at 1 atmospheric pressure, the values of   ΔHandΔSare40.63kJmo l 1 and108.8J K 1 mo l 1 , respectively. The temperature when Gibbs energy change   (ΔG) for this transformation will be zero, is:

                               

MEDIUM
IMPORTANT

The values of  ΔH  and  ΔS for the reaction, C(graphite)+CO2(g)2CO(g)are170kJand170JK1, respectively. This reaction will be spontaneous at

                               

EASY
IMPORTANT

Considering entropy (S) as a thermodynamic parameter, the criterion for the spontaneity of any process is:

                               

EASY
IMPORTANT

Unit of entropy is:

EASY
IMPORTANT

2 mol of an ideal gas at  27°C temperature is expanded reversibly from 2 L to 20 L. Find the entropy change. R=2 cal/mol K    

MEDIUM
IMPORTANT

The enthalpy of vaporization of water at 100°C is 40.63 kJmol-1. Its entropy of vaporization would be

MEDIUM
IMPORTANT

For a spontaneous process,
 

HARD
IMPORTANT

2 mole of an ideal gas at 27°C expands reversibly from 2 litre to 20 litre. The entropy change is: R=2 cal mol-1 K-1

HARD
IMPORTANT

List I (Equations) List II (Type of Processes)
(A) Kp>Q (p) Non-spontaneous
(B) G°<RT ln Q (q) Equilibrium
(C) Kp=Q (r) Spontaneous and endothermic
(D) T>HS (s) Spontaneous

Matching Type Question

HARD
IMPORTANT

The standard entropy change accompanying the cell reaction will be

MEDIUM
IMPORTANT

Enthalpy change for the process,
H2O(ice)H2O(water) is 6.01 kJ mol-1 ,
the entropy change of 1 mole of ice at its melting point will be

HARD
IMPORTANT

Calculate Stotal  hence show whether the following reaction is spontaneous at 25°CHg (s) + O2 (g)  Hg(l) + SO2 (g) H° =-238.6 kJ and S° = +36.7 J K-1

MEDIUM
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For which of the following reactions S is negative?

MEDIUM
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Which of the following processes is nonspontaneous?

MEDIUM
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For the conversion of liquid to solid below the melting point of solid

HARD
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For the process, H2O(l)H2O(g) at 100°C. S is

HARD
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Which member of the pair has larger entropy and why? Na (s) or NaCl (s).

MEDIUM
IMPORTANT

Which member of the pair has larger entropy and why? Xe (g) or Kr (g).

HARD
IMPORTANT

Which member of the pair has larger entropy and why? NO (g) or N2O4 (g).

MEDIUM
IMPORTANT

Which member of the pair has larger entropy and why? CH3OH (l) or C2H5OC2H5 (l).