Reaction Quotient

Q.

Ethyl acetate is formed by the reaction between ethanol and acetic acid and the equilibrium is represented as:
$C{H}_{3}COOH\left(l\right)+C_2{H}_{5}OH\left(l\right)\leftrightarrow C{H}_{3}COO{C}_2{H}_5\left(l\right)+H_{2}O\left(l\right)$

(i) Write the concentration ratio (reaction quotient), Qc, for this reaction (note: water is not in excess and is not a solvent in this reaction)

(ii) At 293 K, if one starts with 1.00 mol of acetic acid and 0.18 mol of ethanol, there is 0.171 mol of ethyl acetate in the final equilibrium mixture. Calculate the equilibrium constant.

(iii) Starting with 0.5 mol of ethanol and 1.0 mol of acetic acid and maintaining it at 293 K, 0.214 mol of ethyl acetate is found after some time. Has equilibrium been reached?

Q.

For the reaction$\underset{\mathrm{Dinitrogen}\mathrm{pentoxide}}{\underbrace{2{\mathrm{N}}_2{\mathrm{O}}_5\left(\mathrm{g}\right)}}\to \underset{\mathrm{Nitrogen}\mathrm{dioxide}}{\underbrace{4{\mathrm{NO}}_2}}\left(\mathrm{g}\right)+\underset{\mathrm{Oxygen}}{\underbrace{{\mathrm{O}}_2\left(\mathrm{g}\right)}}$. The rate of formation of ${\mathrm{NO}}_2\left(\mathrm{g}\right)$is $2.8\times {10}^{-3}{\mathrm{Ms}}^{-1}$. Calculate the rate of disappearance of ${\mathrm{N}}_2{\mathrm{O}}_5\left(\mathrm{g}\right)$.

Q. For the equilibrium
$LiCl.3N{H}_3\left(s\right)\rightleftharpoons LiCl.N{H}_3\left(s\right)+2N{H}_3\left(g\right);$
$K_p=9at{m}^2$ at ${37}^{\circ }C.$ A $5L$ vessel contains $0.1$ mole of $LiCl.N{H}_3$. How many moles of $N{H}_3$ should be added to the flask at this tremperature to derive the backward reaction for completion?
Use : $R=0.082atmL/molK$

1. $0.2$
2. $0.59$
3. $0.69$
4. $0.79$

Q. The optical rotations of sucrose in $0.5MHCl$ at ${35}^o\text{C}$ at various time intervals are given below. The reaction of sucrose with HCl follows first order reaction. Find the rate constant of the given reaction.

Time (minutes)	0	10	20	30	40	$\infty$
Rotation (degrees)	+32.4	+28.8	+25.5	+22.4	+19.6	-11.1

Take, $ln1.09=0.086$

1. $16.2\times {10}^{-4}$
2. $8.6\times {10}^{-3}$
3. $8.6\times {10}^{-2}$
4. $4.3\times {10}^{-2}$

Q. The Reaction Quotient (Q) for the reaction $N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$ is given by $Q=\frac{[N{H}_3{]}^2}{\left[N_2\right][H_2{]}^3}$, the reaction will shift in forward direction if :

1. $Q=K_c$
2. $Q=0$
3. $Q<K_c$
4. $Q>K_c$

Q. Calculate the equilibrium constant for the reaction at 25 ºC.

1. 10 +26.33

2. 10 --20.69

3. 10 +20.69

4. 10 --26.33

Q. 2HI=H2+I2 ( reversible reaction) 2 moles of HI is introduced in 1 litre container. If 60% of HI is decomposed and attain the equilibrium, find the value of Kc.

Q.

For a reaction

$\mathrm{X}+\mathrm{Y}\rightleftharpoons 2\mathrm{Z}$

$1.0$ mol of $\mathrm{X}$, $1.5$mol of $\mathrm{Y}$ and $0.5$ mol of Z were taken in a $1$ $\mathrm{L}$ vessel and allowed to react. At equilibrium, the concentration of $\mathrm{Z}$ was$1.0$ $\mathrm{mol}{\mathrm{L}}^{-1}$. The equilibrium constant of reaction is $\frac{\mathrm{x}}{15}$. The value of $\mathrm{x}$ is _________.

Q.

At 700 K, equilibrium constant for the reaction

is 54.8. If 0.5 molL^–1 of HI_(g) is present at equilibrium at 700 K, what are the concentration of H_2(g) and I_2(g) assuming that we initially started with HI_(g) and allowed it to reach equilibrium at 700 K?

Q.

n-factor for the following reaction is :
${\mathrm{FeS}}_2\to {\mathrm{Fe}}_2{\mathrm{O}}_3+{\mathrm{SO}}_2$

1. 8

2. 9

3. 10

4. 11

Q. For the reaction A + B= Products, a. On doubling the initial concentration of A only the rate of reaction is also doubled & b. On doubling the initial concentration of both A& B, there is A change in rate of reaction by A factor of 8. The rate of reaction is given by:- ?

Q. The $K_P$ value for the reaction $H_2\left(g\right)+I_2\left(g\right)\rightleftharpoons 2HI\left(g\right)$ at $460{}^{o}C$ is 49. If the initial pressure of $H_2$ and $I_2$ is $0.5atm$ respectively, determine the partial pressure of $H_2$ at equilibrium.

1. $0.22atm$
2. $0.11atm$
3. $0.02atm$
4. $0.01atm$

Q.

The equilibrium composition for the reaction is -

$PC{l}_3+C{l}_2\rightleftharpoons PC{l}_5$

0.20 0.10 0.40 mole/litre

If 0.20 mole of $C{l}_2$ is added at same temp. Find equilibrium concentration of $PC{l}_5$ $K_C=20$

1. 1.20 moles

2. 0.48 moles

3. 0.38 moles

4. 0.56 moles

Q.

A mixture of 1.57 mol of $N_2$, 1.92 mol of $H_2$ and 8.13 mol of $N{H}_3$ is introduced into a 20 L reaction vessel at 500 K. At this temperature, the equilibrium constant, $K_c$ for the reaction
$N_2\left(g\right)+3H_2\left(g\right)\leftrightarrow 2N{H}_3\left(g\right)is1.7\times {10}^2$
Is the reaction mixture at equilibrium? If not, what is the direction of the net reaction?

Q.

NO and $B{r}_2$ at initial partial pressure of 98.4 and 41.3 torr, respectively were allowed to react at 300K. At equilibrium the total pressure was 110.5 torr. Calculate the value of KP for the following reaction at 300K.

$2NO\left(g\right)+B{r}_2\left(g\right)\rightleftharpoons 2NOBr\left(g\right)$

1. 12.4

2. 13.4

3. 15.4

4. 17.4

Q. At a certain temperature (T), the equilibrium constant $\left(K_c\right)$ is 1 for the reaction $N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$
If 2 moles of $N_2,$ 4 moles of $H_2,$ 6 moles of $N{H}_3$ and 3 moles of inert gas are introduced into a two litre rigid vessel at constant temperature T. It has been found that equilibrium concentration of $H_2$ and $N{H}_3$ are equal then what is the equilibrium concentration of $N_2$ (in M)?

Q.

What happens if the $∆\mathrm{G}$ is positive ?

Q.

Equilibrium constant, $K_c$ for the reaction.

$N_2\left(g\right)+3H_2(g\leftrightarrow 2N{H}_3(g)$ at 500 K is 0.061.
At a particular time, the analysis shows that composition of the reaction mixture is 3.0 mol $L^{-1}{N}_2,2.0mol{L}^{-1}{H}_2$ and 0.5 mol $L^{-1}N{H}_3$, Is the reaction at equilibrium? If not in which direction does the reaction tend to proceed to reach equilibrium?

Q. Calculate the value of $Q_c$ value, for the given reaction below. Also, given the concentration of all the species involved at a certain time:
$CO\left(g\right)+H_{2}O\left(g\right)\rightleftharpoons C{O}_2\left(g\right)+H_2\left(g\right)\left[C{O}_2\right]=2M\left[H_2\right]=2M\left[CO\right]=1M\left[H_{2}O\right]=1M$

If $K_c=1$ , in which direction the reaction will shift to attain equilibrium?

1. $Q_C=2$ and backward
2. $Q_C=4$ and forward
3. $Q_C=4$ and backward
4. $Q_C=2$ and forward

Q.

If K_p for the reaction, A(g)+2B(g)⇌3C(g)+D(g) is 0.05 atm at 1000K. Its K_c in terms of unit R will be:

1. 
2. 
3. 
4. 

Q. For a reaction,
$HCl\left(aq\right)+NaOH\left(aq\right)\rightleftharpoons NaCl\left(aq\right)+H_{2}O\left(l\right)Given{K}_c=0.5,\left[HCl\right]=3M,\left[NaOH\right]=4M,\left[NaCl\right]=6M$
Find $Q_c$ and the direction in which reaction will shift.

1. $Q_c=0.5$ ; reaction shifts in backward direction
2. $Q_c=0.5$ ; reaction shifts in forward direction
3. $Q_c=0.5$ ; reaction is at equilibrium
4. $Q_c=1$ ; reaction shifts in backward direction

Q. calculate the equilibrium constant for the reaction :- Mg(s) | Mg2+(0.0001M) || Cu2+(0.0001M) | Cu(s) Given E^° (Mg2+/Mg)= -2.37 V, E^°=+0.34 V.

Q. At a certain temperature, equilibrium constant $K_c=4\times {10}^{-2}$ for the reaction $N_2\left(g\right)+O_2\left(g\right)\rightleftharpoons 2NO\left(g\right)$
If we take $1.5mol$ of NO and $2mol$ each of $N_{2}and{O}_2$ in $5L$ vessel, what would be the equilibrium concentration of $NO$ (in $mol/L$)?

Q. Form the Ellingham graph between Gibb's energy and temperature, out of $C$ and $CO$ which is a better reducing agent for $ZnO$?

1. Carbon
2. $CO$
3. Both of these
4. None of these

Q. Which of the following do not change the value of equilibrium constant (K) for a reaction?

1. Addition of catalyst
   
2. Increase in temperature
   
3. Increase in pressure
   
4. Removal of one of the product

Q. Consider the following reaction and its equilibrium constant:
$N_2{O}_4\left(g\right)\rightleftharpoons 2N{O}_2\left(g\right)Kc=5.85\times {10}^{-3}$

A reaction mixture at a particular time, t contains: $\left[N{O}_2\right]=0.025Mand\left[N_2{O}_4\right]=0.033M.$ Calculate $Qc$, and determine the direction in which the reaction will proceed.

1. $1.9\times {10}^{-3}$, the reaction will proceed in forward direction
2. $1.9\times {10}^{-2}$, the reaction will proceed in backward direction
3. None of the above
4. $5.85\times {10}^{-3}$, it will be equal to the equilibrium constant

Q. Which of the following statements about the reaction quotient, Q , are correct?

1. The reaction quotient, Q and the equilibrium constant always have the same value
2. Q may be greater than or less than or equal to the value of $K_c$
3. Value of Q does not depend on concentration of the products in a reaction
4. Q =1 at equilibrium

Q. $K_C$ for the reaction,
$A_{\left(g\right)}+B_{\left(g\right)}\rightleftharpoons C_{\left(g\right)}+D_{\left(g\right)}$ is $20$ at $25{}^{\circ }\text{C}$. If a container contains $1,2,4,5$ moles per litre of $A_{\left(g\right)},B_{\left(g\right)},C_{\left(g\right)}$ and $D_{\left(g\right)}$ respectively at $25{}^{\circ }\text{C}$, then the reaction shall:

1. Proceeds from left to right
2. Proceeds from right to left
3. Be at equilibrium
4. None

Q.

For a hypothetical reaction $A\left(g\right)+3B\left(g\right)\rightleftharpoons 2C\left(g\right)\Delta H=–100kJ$ and $\Delta S=–200J{K}^{-1}$
Then the temperature at which the reaction will be in equilibrium.

1. 480 K

2. 500K

3. 520 K

4. 510 K

Q. 8 moles of a gas $A{B}_3$ attain equilibrium in a closed container of volume $1{dm}^3$ as,

1. $72{mol}^2{L}^{-2}$
2. $36{mol}^2{L}^{-2}$
3. $3{mol}^2{L}^{-2}$
4. $27{mol}^2{L}^{-2}$