Thermodynamics of Equilibrium

IMPORTANT

Thermodynamics of Equilibrium: Overview

This topic covers concepts, such as, Relationship between Equilibrium Constant (K) & Reaction Quotient (Q) and Gibbs Free Energy Change (ΔG) etc.

Important Questions on Thermodynamics of Equilibrium

MEDIUM
IMPORTANT

The Haber’s process for the formation of  NH 3 at 298 K is N2+3H22NH3;ΔH=46.0KJ. Which of the following is the correct statement?

EASY
IMPORTANT

The enthalpy and entropy change for the reaction

  B r 2 (l)+C l 2 (g)2BrCl(g)

are   30kJmo l 1 and105J K 1 mo l 1  respectively. The temperature at which the reaction will be in equilibrium is

                               

HARD
IMPORTANT

In a one-litre flask, 6 moles of A undergoes the reaction A( g)P( g). The progress of product formation at two temperatures (in Kelvin), T1 and T2, is shown in the figure:

Question Image

If T1=2T2 andΔG2o-ΔG1o=RT2lnx , then the value of x is
[ ΔG1o and ΔG2o are standard Gibb's free energy change for the reaction at temperatures T1 and T2, respectively.]

MEDIUM
IMPORTANT

What is the (approx) partial pressure of CO2at equilibrium at 427°C?

CaCO3sCaOs+CO2g   G=-13.5 kJ

EASY
IMPORTANT

Which of the following is correct at equilibrium?

HARD
IMPORTANT

Select the graph which can be used to determine standard free energy of the reaction given below:

CaCO3(s)CaO(s)+CO2(g)
Assume that the reaction is at equilibrium.

EASY
IMPORTANT

Among the following set of conditions, which condition necessarily holds true for a non-feasible process?
(Where, K=equilibrium constant)

EASY
IMPORTANT

Calculate the temperature given that the value of Kc = 103 and ΔGf° of A, B and C are 100, 200 and 500 kJ/mol  and the reactants A and B is in equilibrium with C.

MEDIUM
IMPORTANT

The value of Kc for the following reaction at 298 K is:

2NH3(g)+CO2(g)NH2CONH2(aq)+2H2O()  

Given, standard Gibbs energy change ΔG° at the given temperature is -13.6kJ/mol-1

EASY
IMPORTANT

For the following reaction,

C2H6(g)C2H4(g)+H2(g)

the kp=0.05 atm. What is the value of ΔG° of the reaction at 627C?

MEDIUM
IMPORTANT

Consider that for a hypothetical reaction, ΔH° and ΔS° are -30 kJ mol-1 and -100 JK-1mol-1 at 300K. What is the equilibrium constant for the reaction at 298 K?

MEDIUM
IMPORTANT

Consider the curve between ln K and 1/T. Which plot will be correct for exothermic reaction?

HARD
IMPORTANT

Among the following, select the correct option if there is an increase of pressure on ice water system at a constant temperature.

EASY
IMPORTANT

The plot of log K against 1T is a straight line with a positive slope (K being the equilibrium constant of a reaction). The correct statement among the following is:

MEDIUM
IMPORTANT

What is the value of free energy change for a reversible reaction at equilibrium?

EASY
IMPORTANT

Only a few reactions are simple or straight forward, $i . e .$ purely first, second or third order reactions. But in most of the reactions, the interpretation of variety of data becomes difficult due to several other reactions taking place simultaneously along with the main reaction and thus smooth progress of the reaction is disturbed. Such reactions include the following different types. The reactions, in which a substance reacts or decomposes in more than one way, are called parallel or competing or side reaction. The reactions which take place exclusively on the walls of containing vessels are known as surface reactions. The reactions in which the products of chemical change react together to form the original reactants are called reversible reactions or opposing reactions or counter reactions. The reactions which proceeds from reactants to final products through one or more intermediate stages are called consecutive reactions.

The relation H=Ea(f)-Ea(b) is valid for:

HARD
IMPORTANT

The ionisation constant of NH4+ in water is 5.6×10-10 at 25°C. The rate constant for the reaction of NH4+ and OH- to form NH3 and H2O at 25°C is 3.4×1010 L mol-1sec-1. If dissociation constant of water at 25°C is 1.8×10-16. If Kw of water at 60°C is 9.5×10-14, then the heat of neutralisation is:

EASY
IMPORTANT

The change in standard Gibbs energy for a reaction at equilibrium, $eg . \mathrm{PCl}_{5}(g) \rightleftharpoons \mathrm{PCl}_{3}(g)+\mathrm{Cl}_{2}(g),$ on addition of an inert gas at constant pressure and then at constant volume respectively are :

MEDIUM
IMPORTANT

5 moles of N2O4 taken in a one litre flask dissociates to 20% extent to reach equilibrium. What is ΔG° of the reaction ?

N2O4(g)2NO2(g)

HARD
IMPORTANT

Solid CaCO3 is heated in a closed container to 900 K. When equilibrium is reached, the pressure becomes 500 Torr. Similarly, the equilibrium pressure at 1000 K was found to be 2000 Torr. Hence H for the given reaction.

CaCO3(s)CaO(s)+CO2(g)

At this temperature range is: