Chemistry - Chemical Equilibrium
Exam Duration: 45 Mins Total Questions : 30
Which one of the following reactions has the least tendency to go to completion?
- (a)
\(2H_{2}(g)+O_{2}(g)\rightleftharpoons 2H_{2}O; \ K=1.7\times10^{27}\)
- (b)
\(N_{2}(g)+O_{2}(g)\rightleftharpoons 2NO;\ K=5.0\times 10^{-31}\)
- (c)
\(H_{2}(g)+C1_{2}(g)\rightleftharpoons 2HC1(g); \ K=3.2\times10^{16}\)
- (d)
\(2NOC1(g)\rightleftharpoons 2NO(g)+C1_{2}(g);\)
In which of the following does the reaction go almost to completion?
- (a)
\(K_{c}=10^{3}\)
- (b)
\(K_{c}=10^{2}\)
- (c)
\(K_{c}=10^{-2}\)
- (d)
\(K_{c}=10^{-3}\)
The equilibrium constant for the reaction 2X(g)+Y(g)\(\rightleftharpoons \) 2Z(g) is 2.25. What would be the concentration of Y at equilibrium with 2.0 moles of X and 3.0 moles of Z in a litre vessel ?
- (a)
2.25 mol
- (b)
2.0 mol
- (c)
1.0 mol
- (d)
\({1\over2.25}\) mol
The equilibrium constant for the reaction \(H_{2}(g)+CO_{2}(g)\rightleftharpoons H_{2}O(g)+CO(g)\) is 1.8 at \(1000^{o}C.\) If one mole each of \(H_{2}\) and \(CO_{2}\) are placed in one litre flask, the equilibrium concentration of CO at \(1000^{o}C\) will be
- (a)
0.294 mol \(l^{-1}\)
- (b)
0.386 mol \(l^{-1}\)
- (c)
0.575 mol \(l^{-1}\)
- (d)
0.688 mol \(l^{-1}\)
At 700 K, the equilibrium constant for the reaction \(H_{2}(g)+I_{2}(g)\rightleftharpoons 2HI(g)\) is 54.8. If 0.5 mol \(l^{-1}\) of HI(g) is present at equilibrium at 700 K, assuming that we initially started with HI(g) and allowed to reach equilibrium at 700 K. the concemtration of \(H_{2}\) or \(I_{2}\) each would be
- (a)
\(6.56\times10^{-3} mol\ l^{-1}\)
- (b)
\(6.56\times10^{-5} mol\ l^{-1}\)
- (c)
\(6.56\times10^{-6} mol\ l^{-1}\)
- (d)
\(6.56\times10^{-8} mol\ l^{-1}\)
The oxidation of \(SO_{2}\) will be maximum if
- (a)
both temperature and pressure are increased
- (b)
both temperature and pressure are decreased
- (c)
temperature is decreased and pressure is increased
- (d)
temperature is increased and pressure is kept constant.
The equilibrium constant K for the reaction \(N_{2}+3H_{2}??\rightleftharpoons 2NH_{3}\) is \(1.64\times10^{-14}\) and \(400^{o}C.\) The equilibrium constant at \(500^{o}C.\) would be: [given, the heat of reaction in this range is -25140 cal and R=1.987 cal]
- (a)
\(1.44\times10^{-5}\)
- (b)
\(14.4\times10^{-5}\)
- (c)
\(1.64\times10^{-4}\)
- (d)
\(5.76\times10^{-3}\)
The equilibrium constant for the reaction \(N_{2}+3H_{2}\rightleftharpoons 2NH_{3}\), is K. The equilibrium constant for the reation \(NH_{3}\rightleftharpoons {1\over2}N_{2}+{3\over2}H_{2}\) would be
- (a)
\(\sqrt{K}\)
- (b)
\(\sqrt{1/K}\)
- (c)
1/K
- (d)
\(1/K^{3}\)
One more of \(O_{2}\) combines with 2 moles of \(SO_{3}\) in a container of volume V. At equilibrium it was observed that 2 moles of \(SO_{3}\) are produced. The value of k for the equilibrium would be
- (a)
\(x^{2}V/(1-x)^{3}\)
- (b)
\(4x^{2}/(2-x)^{2}(1-x)\)
- (c)
\((1-x)^{3}/x^{2}V\)
- (d)
\(x/(1+x)V\)
The equilibrium constant for the reaction \(2SO_{2}+O_{2}\rightleftharpoons 2SO_{3}\) at a particular temperature is 3.5 \(atm^{-1}\). If equal volumes of SO_{2} and SO_{3} are formed at equalilibrium, the partial pressure of oxygen would be
- (a)
\(0.35 \ atm\)
- (b)
\(0.29 \ atm\)
- (c)
\(0.17 \ atm\)
- (d)
\(0.11 \ atm\)
A reaction is \(A+B\rightleftharpoons C+D.\) Initially, we start with equal concentrations of A and B. At equlilibrium we find the moles of C is two times of A. What is the equilibrium constant of the reaction ?
- (a)
2
- (b)
4
- (c)
1/2
- (d)
1/4
The equilibrium constant in a reversible chemical reaction at a given temperature
- (a)
depends on the initial concentration of the reactants
- (b)
depends on the concentration of one of the produsts at equilibrium
- (c)
does not depend on the initial concentrations of reactants
- (d)
is not characteristic of the reaction
In a reversible chemical reaction having two reactants in equilibrium, if the concentrations of the reactants are doubled then the equilibrium constant will
- (a)
also be doubled
- (b)
be halved
- (c)
become one -fourth
- (d)
remain the same
For a chemical equilibrium \(A(g)+B(g)\begin{matrix} 1\quad atm \\ \rightleftharpoons \\ { 400 }^{ o }C \end{matrix} \ C(g) \ - \ Q \ cal\)
- (a)
\(K_{p}=K_{c}\)
- (b)
\(K_{p}>K_{c}\)
- (c)
\(K_{p}
- (d)
\(K_{c}\) is independent of temperature
In an equilibrium A+B\(\rightleftharpoons \) C+D, A and B are mixed in a vessel at temperature T. The initial concetration of A os twice the initial concentration of B. After the equilibrium has reached, concentration of C becomes thrice the equilibrium concentration of C becomes thrice the equilibrium concentration of B. The value of \(K_{c}\) for the above reaction would be
- (a)
1.0
- (b)
1.2
- (c)
1.6
- (d)
1.8
For the reaction
\(CO(g)+1/2 \ O_{2}(g)\rightarrow CO_{2}(g), {K_{p}\over K_{c}} \) is
- (a)
RT
- (b)
\((RT)^{-1}\)
- (c)
\((RT)^{-1/2}\)
- (d)
\(RT^{1/2}\)
Which of the following is not general characteristic of equilibrium involving physical processes?
- (a)
Equilibrium is possible only in a closed system at a given temperature.
- (b)
All measurable properties of the system remain constant
- (c)
All the physical processes stop at equilibrium
- (d)
The opposing processes occur at the same rate and there is dynamic but stable condition.
In any chemical reaction, equilibrium is supposed to be attain when
- (a)
mutual opposite reactions start
- (b)
concentration of reactants and resulting products are equal
- (c)
concentration of reactants and resulting products are equal
- (d)
the temperature of mutual opposite reactions become equal
The unit of equilibrium constant, K for the reaction, \(A+B\rightleftharpoons C\) would be
- (a)
mol L-1
- (b)
mol L
- (c)
mol-1 L
- (d)
\(1\over mol \ L\)
For the system \( 3A+2B\rightleftharpoons C\) the equilibrium constant is shown by the expression
- (a)
\(\frac { \begin{bmatrix} A \end{bmatrix}^{ 3 }\begin{bmatrix} B \end{bmatrix}^{ 2 } }{ \begin{bmatrix} C \end{bmatrix} } \)
- (b)
\(\frac { \begin{bmatrix} C \end{bmatrix} }{ \begin{bmatrix} A \end{bmatrix}^{ 3 }\begin{bmatrix} B \end{bmatrix}^{ 2 } } \)
- (c)
\(\frac { \begin{bmatrix} 3A \end{bmatrix}\begin{bmatrix} 2B \end{bmatrix} }{ \begin{bmatrix} C \end{bmatrix} } \)
- (d)
\(\frac { \begin{bmatrix} C \end{bmatrix} }{ \begin{bmatrix} 3A \end{bmatrix}\begin{bmatrix} 2B \end{bmatrix} } \)
Equilibrium constant K1 and K2 for the following chemical equilibria \(NO(g)+\frac { 1 }{ 2 } O_{ 2 }(g)\rightleftharpoons NO_{ 2 }(g)\) and, \(2NO_{ 2 }(g)\rightleftharpoons 2NO(g)+O_{ 2 }(g)\) are related as
- (a)
\(K_1={1\over K_2}\)
- (b)
\(K_2={1\over K_1}\)
- (c)
\(K_2={1\over K_1^2}\)
- (d)
\(K_1={1\over K_2^2}\)
What is the effect of having the pressure by doubling the volume on the following reaction at 500oC?
\(H_{ 2 }(g)+I_{ 2 }(g)\rightleftharpoons 2HI(g)\)
- (a)
Shift to products side
- (b)
Shift to reactants side
- (c)
Liquefaction of HI
- (d)
No effect
Match the following and choose the correct option.
Column I | Column II |
---|---|
A. \(\Delta G>0\) | 1. K>1 |
B. \(\Delta G<0\) | 2. K=1 |
C. \(\Delta G=0\) | 3. K=0 |
4. K<1 |
- (a)
A B C 2 4 1 - (b)
A B C 1 3 2 - (c)
A B C 4 1 2 - (d)
A B C 4 2 1
Which of the following options will be correct for the stage of half completion of the reaction \(A\rightleftharpoons B\)?
- (a)
\(\Delta G^o=0\)
- (b)
\(\Delta G^o>0\)
- (c)
\(\Delta G^o<0\)
- (d)
\(\Delta G^o=-RT\ ln \ 2\)
In which of the following reactions, the equilibrium remains unaffected on addition of small amount of argon at constant volume?
- (a)
\(H_{ 2 }(g)+I_{ 2 }(g)\rightleftharpoons 2HI(g)\)
- (b)
\(PCl_{ 5 }(g)\rightleftharpoons 2PCl_{ 3 }(g)+Cl_{ 2 }(g)\)
- (c)
\(N_{ 2 }(g)+3H_{ 2 }(g)\rightleftharpoons 2NH_{ 3 }(g)\)
- (d)
The equilibrium will remain uneffected in all the three cases
What is the equilibrium constant, K for the following reaction at 400K?
\(2NOCl(g)\rightleftharpoons 2NO(g)+Cl_{ 2 }(g)\); \(\Delta H=77.2kJmol^{-1}\) and \(\Delta S=122JK^{-1}mol^{-1}\) at 400K.
- (a)
-3.708
- (b)
1.95X10-4
- (c)
2.8X104
- (d)
1.67X10-5
The incorrect expression among the following is
- (a)
\({\Delta G_{syatem}\over \Delta S_{total}}=-T\)
- (b)
In isothermal process, \(w_{reversible}=-nRT \ In \ {V_f\over V_i}\)
- (c)
In \(K^o={{\Delta H^o}-{T\Delta S^o}\over RT}\)
- (d)
\(K^o=exp(-\Delta G^o/RT)\)
The equilibrium constant (Kc) for the reaction, \(N_{ 2 }(g)+O_{ 2 }(g)\longrightarrow 2NO(g)\), at temperature T is 4X10-4. The value of Kc for the reaction.
\(NO(g)\longrightarrow \frac { 1 }{ 2 } N_{ 2 }(g)+\frac { 1 }{ 2 } O_{ 2 }(g)\) at the same temperature is
- (a)
0.02
- (b)
2.5X102
- (c)
4X10-4
- (d)
50.0
Phosphorus pentachloride dissociates as follows, in a closed reaction vessel, \(PCl_{ 5 }(g)\rightleftharpoons PCl_{ 3 }(g)+Cl_{ 2 }(g)\), If the total pressure, at equilibrium, of the reaction mixture is p and degree of dissociation of PCl5 is x, the partial pressure of PCl3 will be
- (a)
\(({x\over{x+1}})p\)
- (b)
\(({2x\over 1-x})p\)
- (c)
\(({x\over x-1})p\)
- (d)
\(({x\over 1-x})p\)
For the reaction, \(2NO_{ 2 }(g)\rightleftharpoons 2NO(g)+O_{ 2 }(g)\) [Kc=1.8X10-6 at 184oC and R=0.00831kJ/(mol K)] when Kp and Kc are compared at 184oC, it is found that
- (a)
whether Kp is greater than, less than or equal to Kc depends upon the total gas pressure
- (b)
Kp=Kc
- (c)
Kp is less than Kc
- (d)
Kp is greater than Kc