Introduction to Le Chatelier's Principle

Q. Le-chatelier principle is applicable

1. Both for physical and chemical equilibrium
2. Only for chemical equilibrium
3. Only for physical equilibrium
4. Neither for B nor for C

Q. The following reactions are known to occur in the body $C{O}_2+H_{2}O\rightleftharpoons H_{2}C{O}_3\rightleftharpoons H^{+}+HC{O}_3^{-}$
If $C{O}_2$ escapes from the system

1. pH will decreases
2. Hydrogen ion concentration will decrease
3. $H_{2}C{O}_3$ concentration will remain unchanged
4. The forward reaction will be favoured

Q. The equilibrium constant for the reaction $B{r}_2\left(l\right)+C{l}_2\left(g\right)\rightleftharpoons 2BrCl\left(g\right)$ at ${27}^{\circ }$C is $K_p=1\text{atm}$. In a closed container of volume $164\text{L}$ initially 10 moles of $C{l}_2$ are present at ${27}^{\circ }C$. What minimum moles of $B{r}_2\left(l\right)$ must be introduced into this container so that the above equilibrium is maintained at a total pressure of 2.25 atm? Vapour pressure of $B{r}_2\left(l\right)$ at ${27}^{\circ }$C is 0.25 atm. Assume that volume occupied by the liquid is negligible.
[$R=0.082{\text{Latmmol}}^{-1}{\text{K}}^{-1}$ , Atomic mass of bromine = 80]

Q. Le-Chatelier principle is not applicable to

1. 
   $H_2\left(g\right)+I_2\left(g\right)\rightleftharpoons 2HI\left(g\right)$
   
2. 
   $Fe\left(s\right)+S\left(s\right)\rightleftharpoons FeS\left(s\right)$
   
3. $N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$
   
4. $N_2\left(g\right)+O_2\left(g\right)\rightleftharpoons 2NO\left(g\right)$
   

Q. For the reversible reaction :
$N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)+heat$
The equilibrium shifts in forward direction-

1. By increasing the concentration of $N{H}_3\left(g\right)$
2. By decreasing the pressure
3. By decreasing the concentrations of $N_2\left(g\right)$ and $H_2\left(g\right)$
4. By increasing pressure and decreasing temperature

Q.

4HCl (g) + O₂ (g) ⇌ 2H₂O (g) + 2Cl₂ (g) ΔH° = -114 kJ

What shifts the equilibrium to the left?

1. removing steam

2. increasing the total gas pressure

3. decreasing volume of the container

4. raising the temperature

Q.

A hypothetical reaction : $A_{\left(g\right)}+B_{\left(g\right)}\rightleftharpoons C_{\left(g\right)}+D_{\left(g\right)}$ occurs in a single step, the specific rate constant of forward reaction at TK is $2.0\times {10}^{-3}mo{l}^{-1}L{s}^{-1}$. When start is made with equimolar amounts of A and B, it is found that the concentration of A is twice that of C at equilibrium. The specific rate constant of the backward reaction is ?

1. $5.0\times {10}^{-4}mo{l}^{-1}L{s}^{-1}$

2. $8.0\times {10}^{-3}mo{l}^{-1}L{s}^{-1}$

3. $1.5\times {10}^{2}mo{l}^{-1}L{s}^{-1}$

4. $Noneofthese$

Q. When hydrochloric acid is added to cobalt nitrate solution at room temperature, the following reaction takes place and the reaction mixture becomes blue. On cooling the mixture it becomes pink. On the basis of this information mark the correct answer.

$\underset{pink}{\underset{}{\left[Co\right(H_{2}O{)}_6{]}^{3^{+}}\left(aq\right)}}+4C{l}^{-}\left(aq\right)\leftrightharpoons \underset{blue}{\underset{}{\left[C_{o}C{l}_4{]}^{2^{-}}\right(aq)}}+6H_{2}O\left(l\right)$

1. $△H>o$ for the reaction
2. $△H<o$ for the reaction
3. $△H=o$ for the reaction
4. The sign of $△H$ canot be predicted on the basis of this information

Q. If concentration of $O{H}^{-}$ions in the reaction $Fe\left(OH{)}_3\right(s)\leftrightharpoons F{e}^{3+}+(aq)+3O{H}^{-}(aq)$ is decreased by $1/4$ times, then equilibrium concentration of $F{e}^{3+}$will increase by

1. 8 times
2. 16 times
3. 64 times
4. 4 times.

Q. $S{O}_3\left(g\right)+CO\left(g\right)\rightleftharpoons S{O}_2\left(g\right)+C{O}_2\left(g\right)$
Which of the following activity can reduce the equilibrium concentration of $CO$ to half?

1. Increasing pressure twice
2. Increasing the volume of reaction container to two times of its initial value
3. Adding two moles of $C{O}_2$ gas
4. Adding two mole of helium gas at constant pressure

Q. For the reaction
$2Cl{F}_3\left(g\right)\rightleftharpoons C{l}_2\left(g\right)+3F_2\left(g\right)$
$log{K}_{eq}v/s\frac{1}{T}$ (where temperature is in K) curve is obtained as following
Which of the following change will increase the concentration of $C{l}_2$ in an equilibrium mixture of $C{l}_2,F_{2}andCl{F}_3:$

1. Addition of inert gas at constant pressure
   
2. Increase in temperature at constant volume
   
3. Addition of catalyst at equilibrium
   
4. Removal of $F_2\left(g\right)$ at equilibrium

Q.

For the gas phase reaction $C_2{H}_4+H_2\rightleftharpoons C_2{H}_6,$ $\Delta H$ = -32.7kcal carried out in a vessel, the equilibrium concentration of $C_2{H}_4$ can be increased by -

1. increasing the temperature

2. Increasing concentration of $H_2$

3. Decreasing temperature

4. Increasing pressure

Q. The following reactions are known to occur in the body $C{O}_2+H_{2}O\rightleftharpoons H_{2}C{O}_3\rightleftharpoons H^{+}+HC{O}_3^{-}$
If $C{O}_2$ escapes from the system

1. pH will decreases
2. Hydrogen ion concentration will decrease
3. $H_{2}C{O}_3$ concentration will remain unchanged
4. The forward reaction will be favoured

Q.

A reversible reaction is in equilibrium. If a factor is changed which affects it,

then

1. The speed of forward and backward reaction increases

2. The speed of forward and backward reaction decreases

3. Only the speed of that reaction increases which nullifies the factor

   causing increase of speed

4. No difference

Q. In which of the following system, doubling the volume of the container cause a shift to the right?

1. $H_{2\left(g\right)}+C{l}_{2\left(g\right)}\rightleftharpoons 2HC{l}_{\left(g\right)}$
2. $2C{O}_{\left(g\right)}+O_{2\left(g\right)}\rightleftharpoons 2C{O}_{2\left(g\right)}$
3. $N_{2\left(g\right)}+3H_{2\left(g\right)}\rightleftharpoons 2N{H}_{3\left(g\right)}$
4. $PC{l}_{5\left(g\right)}\rightleftharpoons PC{l}_{3\left(g\right)}+C{l}_{2\left(g\right)}$

Q. The effect of increasing the pressure on the equilibrium $2A\left(g\right)+3B\left(g\right)\rightleftharpoons 3A\left(g\right)+2B\left(g\right)$ is

1. Forward reaction is favoured
2. Backward reaction is favoured
3. No effect
4. None of the above

Q. The exothermic formation of $Cl{F}_3$ is represented by the equation $C{l}_{2\left(g\right)}+3F_{2\left(g\right)}\rightleftharpoons 2Cl{F}_{3\left(g\right)}$; $\Delta H=-329kJ$. Which of the following will increase the quantity of $Cl{F}_3$ in an equilibrium mixture of $C{l}_2,F_2$ and $Cl{F}_3?$

1. Increasing the temperature
2. Removing $C{l}_2$
3. Increasing the volume of the container
4. Adding $F_2$

Q. When hydrochloric acid is added to cobalt nitrate solution at room temperature, the following reaction takes place and the reaction mixture becomes blue. On cooling the mixture it becomes pink. On the basis of this information mark the correct answer.

$\underset{pink}{\underset{}{\left[Co\right(H_{2}O{)}_6{]}^{3^{+}}\left(aq\right)}}+4C{l}^{-}\left(aq\right)\leftrightharpoons \underset{blue}{\underset{}{\left[C_{o}C{l}_4{]}^{2^{-}}\right(aq)}}+6H_{2}O\left(l\right)$

1. $△H>o$ for the reaction
2. $△H<o$ for the reaction
3. $△H=o$ for the reaction
4. The sign of $△H$ canot be predicted on the basis of this information

Q. The effect of increasing the pressure on the equilibrium $2A\left(g\right)+3B\left(g\right)\rightleftharpoons 3A\left(g\right)+2B\left(g\right)$ is

1. Forward reaction is favoured
2. Backward reaction is favoured
3. No effect
4. None of the above

Q. The reaction $A\left(g\right)+B\left(g\right)\rightleftharpoons C\left(g\right)+D\left(g\right)+heat$
has reached equilibrium. The reaction may be made to proceed forward by

1. Adding more C
2. Adding more D
3. Decreasing the temperature
4. Increasing the temperature

Q.

When a change is brought about in pressure, temperature or concentration of a reversible reation which has attained equilibrium, the equilibria tries to shift in such a direction which would neutralize the effect of change. This is known as

1. First law of thermodynamics

2. Le-chatelier's principle

3. Ostwald's rule

4. Hess's law of constant heat summation

Q. At constant pressure, which of the following is true for dissociation of $PC{l}_5$(g) for the addition of inert gases?

1. Reduces the dissociation of $PC{l}_5$
2. Increases the dissociation of $PC{l}_5$
3. Does not affect the degree of dissociation of $PC{l}_5$
4. Decrease in the formation of $PC{l}_3\left(g\right)$​

Q. Following two equilibrium is simultaneously established in a container.
$PC{l}_5\left(g\right)\rightleftharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right)$
$CO\left(g\right)+C{l}_2\left(g\right)\rightleftharpoons COC{l}_2\left(g\right)$
If some $Ni\left(s\right)$ is introduced in the container forming $Ni\left(CO{)}_4\right(g)$ then at new equilibrium:

1. $PC{l}_3$ concentration will increase
2. $PC{l}_3$ concentration will decrease
3. $C{l}_2$ concentration will remain same
4. $CO$ concentration will remain same

Q.

The solubility of a solute in water varies with temperature as given by $:S=A{e}^{\frac{-\Delta H}{RT}},\Delta H$ being the enthalpy of solution. For a given solute, variation of In S with temperature is as shown in the figure. The solute is expected to be ?

1. $CaO$

2. $CuS{O}_4$

3. $MgS{O}_4$

4. $CuS{O}_4.5H_{2}O$

Q. The following reactions are known to occur in the body $C{O}_2+H_{2}O\rightleftharpoons H_{2}C{O}_3\rightleftharpoons H^{+}+HC{O}_3^{-}$
If $C{O}_2$ escapes from the system

1. pH will decreases
2. Hydrogen ion concentration will decrease
3. $H_{2}C{O}_3$ concentration will remain unchanged
4. The forward reaction will be favoured

Q. $A{g}^{+}+2N{H}_3\rightleftharpoons \left[Ag\right(N{H}_3{)}_2{]}^{+}$
On adding more $N{H}_3,$ the above equilibrium shifts:

1. In the forward direction
2. In the backward direction
3. The complex dissociation faster
4. None of these

Q. $N_2\left(g\right)+O_2\left(g\right)\rightleftharpoons 2NO\left(g\right)\Delta H=Qcals$, where Q is positive.
In the above reaction which is the essential condition for the higher production of $NO$ ?

1. High temperature
2. High pressure
3. Low temperature
4. Low pressure

Q. The endothermic reaction $M$(g)+ $N$(g)$\to$ $P\left(g\right)$, is allowed to attain an equilibirium at ${25}^{\circ }$. formation of $P$ can be increased by

1. Raising temperature
2. Lowering temperature
3. Keeping temperature constant
4. Decreasing the concentration of $M$ and $N$

Q.

2SO₃ (g) ⇌ 2SO₂ (g) + O₂ (g) ΔH°= +198 kJ

At equilibrium temperature, what shifts the equilibrium to right?

1. removing sulphur trioxide

2. adding sulphur trioxide

3. decreasing the temperature

4. Fastening decomposition of SO₃

Q. In a reaction $A+2B\leftrightharpoons 2C;2molesofA,3$ mole of $Band2moleofC$ are placed in a 2 L flask and the equilibrium concentration of $Cis0.5mole/L.$ The equilibrium constant K for the reaction is:

1. 0.073
2. 0.147
3. 0.05
4. 0.026