Introduction to Reversible and Irreversible Reactions

Q. Hydrolysis of sucrose is given by the following reaction. $\text{Sucrose}+H_{2}O\rightleftharpoons \text{Glucose+Fructose}$
If the equilibrium constant $\left(K_c\right)$ is $2\times {10}^{13}$ at $300K$, the value of ${\Delta }_r{G}^0$ at the same temperature will be :

1. $-8.314Jmo{l}^{-1}{K}^{-1}\times 300K\times \ln (2\times {10}^{13})$
2. $8.314Jmo{l}^{-1}{K}^{-1}\times 300K\times \ln (2\times {10}^{13})$
3. $-8.314Jmo{l}^{-1}\times 300K\times \ln (3\times {10}^{13})$
4. $-8.314Jmo{l}^{-1}{K}^{-1}\times 300K\times \ln (4\times {10}^{13})$

Q. The equilibrium concentration of $[B{]}_{eq}$ for the reversible reaction $A\rightleftharpoons B$ can be evaluated by the expression:

1. $K_c[A{]}_{eq}$
2. $\frac{k_f}{k_b}\left[A\right]e_{eq}$
3. $k_f{k}_b^{-1}[A{]}_{eq}$
4. $k_f{k}_b[A{]}^{-1}$

Q. $2\text{mol}$ of $PC{l}_5$ were heated to $327{}^{o}C$ in a closed $2L$ vessel and when equilibrium was achieved, $PC{l}_5$ was found to be $40\%$ dissociated into $PC{l}_3$ and $C{l}_2.$ What will be the equilibrium constant $\left(K_C\right)$ for the reaction:

1. $1.267{\text{mol L}}^{-1}$
2. $0.267{\text{mol L}}^{-1}$
3. $1.967{\text{mol L}}^{-1}$
4. $2.967{\text{mol L}}^{-1}$

Q. The vapour density of a mixture containing $N{O}_2$ and $N_2{O}_4$ is 27.6. The mole fraction of $N{O}_2$ in the mixture will be :

1. 0.2
2. 0.4
3. 0.6
4. 0.8

Q. The reactions $PC{l}_5\left(g\right)\rightleftharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right)$ and $COC{l}_2\left(g\right)\rightleftharpoons CO\left(g\right)+C{l}_2\left(g\right)$ are simultaneously in equilibrium at constant volume. A few moles of $CO\left(g\right)$ are introduced into the vessel. After some time, the new equilibrium concentration of

1. $PC{l}_5\text{will remain unchanged}$
2. $C{l}_2\text{will be greater}$
3. $PC{l}_5\text{will become less}$
4. $PC{l}_5\text{will become greater}$

Q. Vapour density of $PC{l}_5$ is 104.16 but when heated at 230${}^{o}C$ its vapour density is reduced to 62. The degree of dissociation of $PC{l}_5$ at this temperature will be:

1. $6.8$%
2. $60$%
3. $46$%
4. $68$%

Q. 20 ml of mixture of CO and $H_2$ were mixed with excess of $O_2$ and exploded and cooled . There was a volume contraction of 18 ml . All volume measurements corresponds to room temperature $\left({27}^{0}C\right)$ and one atmosphere pressure . Determine the volume ratio $V_1:V_2$ of CO and $H_2$ in the original mixture.

1. 1 : 2
2. 3 : 2
3. 2 : 3
4. 4 : 1

Q. Two moles of $P{Cl}_5$ were introduced in a $2$ litre flask and heated at $600K$ to attain equilibrium. $P{Cl}_5$ was found to be $40$% dissociated into $P{Cl}_3$, ${Cl}_2$. Calculate the value of $K_c$.

Q.

For the reaction $PC{l}_5$ (g) $\leftrightharpoons$ $PC{l}_3$ (g) + $C{l}_2$ (g) if we start with only a moles of $PC{l}_5$
$\begin{array}{cccc}& PC{l}_5& PC{l}_3& C{l}_2\left(g\right)\\ Molest=0& a& 0& 0\\ MolesAtEq.& a(1-\alpha )& a\alpha & a\alpha \end{array}$
$\alpha$ is called the degree of dissociation - True or false?

1. True

2. False

Q. Consider the following reaction sequence,
${CH}_{3}C\equiv CH\underset{HCl}{\overset{2mole}{\to }}A\underset{aq.KOH}{\overset{Heat}{\to }}B$
The products (A) and (B) are, respectively :

1. (A): ${CH}_3{CH}_2{CHCl}_2$ and (B): ${CH}_3{CH}_{2}CHO$
2. (A): ${CH}_3{C\left(Cl\right)}_2{CH}_3$ and (B): ${CH}_3{COCH}_3$
3. (A): ${CH}_3{C\left(Cl\right)}_2{CH}_3$ and (B): ${CH}_{3}C\equiv CH$
4. (A): ${CH}_3{CH\left(Cl\right)CH}_{2}Cl$ and (B): ${CH}_3{CH\left(OH\right)CH}_{2}Cl$

Q.

For the reaction $PC{l}_5$ (g) $\leftrightharpoons$ $PC{l}_3$ (g) + $C{l}_2$ (g) if we start with only a moles of $PC{l}_5$
$\begin{array}{cccc}& PC{l}_5& PC{l}_3& C{l}_2\left(g\right)\\ Molest=0& a& 0& 0\\ MolesAtEq.& a(1-\alpha )& a\alpha & a\alpha \end{array}$
$\alpha$ is called the degree of dissociation - True or false?

1. True

2. False

Q.

$C{H}_{3}COOH\left(l\right)+C_2{H}_{5}OH\left(l\right)\rightleftharpoons C{H}_{3}COO{C}_2{H}_5\left(l\right)+H_{2}O\left(l\right)$

In the above reaction, one mole of each of acetic acid and alcohol are heated in the presence of

little conc. $H_{2}S{O}_4$. On equilibrium being attained

1. 1 mole of ethyl acetate is formed

2. 2 mole of ethyl acetate are formed

3. $\frac{1}{2}$ moles of ethyl acetate is formed

4. $\frac{2}{3}$ moles of ethyl acetate is formed

Q.

For the reaction $PC{l}_5$ (g) $\leftrightharpoons$ $PC{l}_3$ (g) + $C{l}_2$ (g) if we start with only a moles of $PC{l}_5$
$\begin{array}{cccc}& PC{l}_5& PC{l}_3& C{l}_2\left(g\right)\\ Molest=0& a& 0& 0\\ MolesAtEq.& a(1-\alpha )& a\alpha & a\alpha \end{array}$
$\alpha$ is called the degree of dissociation - True or false?

1. True

2. False

Q. $2$ mole each of $P{Cl}_3$ and ${Cl}_2$ and $1$ mole of $P{Cl}_3$ are taken in $5$ lt. flask at ${27}^{o}C$. After following equilibrium is attained in gaseous phase, $P{Cl}_5\rightleftharpoons P{Cl}_3+{Cl}_2$. $P{Cl}_5$ is found to be $40$% dissociated. Calculate equilibrium constant $K_C$.

Q. At ${1200}^{o}C$, mixture of $C{l}_2$ and $Cl$ atoms (both in gaseous state) effuses 1.16 times faster than krypton effuses under identical conditions. The fraction of chlorine molecules dissociated into atoms is approximate:

1. 22%
2. 87%
3. 13%
4. 44%

Q. The alkylation of benzene with n-propyl chloride in the presence of anhydrous ${AlCl}_3$ produces:

1. n-propyl benzene
2. isopropyl benzene
3. o-dipropyl benzene
4. a mixture of all of these

Q.

$C{H}_{3}COOH\left(l\right)+C_2{H}_{5}OH\left(l\right)\rightleftharpoons C{H}_{3}COO{C}_2{H}_5\left(l\right)+H_{2}O\left(l\right)$

In the above reaction, one mole of each of acetic acid and alcohol are heated in the presence of

little conc. $H_{2}S{O}_4$. On equilibrium being attained

1. 1 mole of ethyl acetate is formed

2. 2 mole of ethyl acetate are formed

3. $\frac{1}{2}$ moles of ethyl acetate is formed

4. $\frac{2}{3}$ moles of ethyl acetate is formed

Q. If different quantities of ethyl alcohol and acetic acid are used in the reversible reaction $C{H}_{3}COOH+C_2{H}_{5}OH\iff C{H}_{3}COO{C}_2{H}_5+H_{2}O$
then the equilibrium constant will have the values:

1. different in all cases
2. same in all cases
3. higher in cases when higher concentration of acetic acid is used
4. higher in cases when higher concentration of ethyl alcohol is used

Q. 2 mole each of $PC{l}_5$ and $C{l}_2$ and 1 mole of $PC{l}_3$ are taken in 5lt. flask at ${27}^{o}C$. After following equilibrium is attained in gaseous phase, $PC{l}_5\rightleftharpoons PC{l}_3+C{l}_2,PC{l}_5$ is found to be 40% dissociated. Calculate equilibrium constant $K_c$.

Q. The following equilibrium constants were determined at $1120K$:
$2CO\left(g\right)\rightleftharpoons C\left(s\right)+C{O}_2\left(g\right);K_{p1}={10}^{-14}{\text{atm}}^{-1}$
$CO\left(g\right)+C{l}_2\left(g\right)\rightleftharpoons COC{l}_2\left(g\right);K_{p2}=6\times {10}^{-3}{\text{atm}}^{-1}$
What is the equilibrium constant $K_P$ for the following reaction at same temperature?
$C\left(s\right)+C{O}_2\left(g\right)+2C{l}_2\left(g\right)\rightleftharpoons 2COC{l}_2\left(g\right)$

1. $6\times {10}^8{\text{atm}}^{-1}$
2. $36\times {10}^{11}{\text{atm}}^{-1}$
3. $36\times {10}^8{\text{atm}}^{-1}$
4. $6\times {10}^{11}{\text{atm}}^{-1}$

Q. Find $K_p$ for the following reactio,
$S{O}_2{Cl}_2\left(g\right)\rightleftharpoons S{O}_2\left(g\right)+{Cl}_2\left(g\right)$
If sulphuryl chloride decomposes to the extent of $91.2$% at ${102}^{o}C$ and total pressure $1$ atmosphere

Q.

$C{H}_{3}COOH\left(l\right)+C_2{H}_{5}OH\left(l\right)\rightleftharpoons C{H}_{3}COO{C}_2{H}_5\left(l\right)+H_{2}O\left(l\right)$

In the above reaction, one mole of each of acetic acid and alcohol are heated in the presence of

little conc. $H_{2}S{O}_4$. On equilibrium being attained

1. 1 mole of ethyl acetate is formed

2. 2 mole of ethyl acetate are formed

3. 1/2 moles of ethyl acetate is formed

4. 2/3 moles of ethyl acetate is formed

Q. A mixture of 2 moles of $C{H}_4$ & 34 gms of $H_{2}S$ was placed in an evacuated container, which was then heated to & maintained at ${727}^{\circ }C$. When equilibrium was established in the gaseous reaction $C{H}_4+2H_{2}S\rightleftharpoons C{S}_2+4H_2$; the total pressure in the container was 0.92 atm & the partial pressure of hydrogen was 0.2 atm. What was the volume of the container?

1. 298L
2. 400L
3. 330.18L
4. 480L

Q. Given,
$X\left(g\right)\rightleftharpoons nY\left(g\right)$
If degree of dissociation is $\alpha$, then $K_c$ of the reaction in a vessel of $1$ litre is:

1. $\frac{n{\alpha }^n}{1-\alpha }$
2. $\frac{n\alpha }{1-\alpha }$
3. $\frac{{\left(n\alpha \right)}^n}{1+\alpha }$
4. $\frac{{\left(n\alpha \right)}^n}{1-\alpha }$

Q. 1 mol of a gaseous aliphatic compound $C_n{H}_{3n}{O}_n$ is completely burnt in an excess of oxygen. The contraction in volume is: (assume water get condensed out)

1. $(1+\frac{1}{2}n-\frac{3}{4}m)$
2. $(1+\frac{3}{4}n-\frac{1}{4}m)$
3. $(1-\frac{1}{2}n-\frac{3}{4}m)$
4. $(1+\frac{3}{4}n-\frac{1}{2}n)$.

Q. Vapour density of $PC{l}_5$ at equilibrium is 52.125 at $T^{o}C$. Then degree of dissociation of $PC{l}_5$ is: (Mw = 208.5)

1. 100%
2. 30%
3. 20%
4. 15%

Q. $8$ mole of a gas ${AB}_3$ are introduced into a $1.0{dm}^3$ vessel. It dissociates as:
$2A{B}_3\left(g\right)\rightleftharpoons A_2\left(g\right)+3B_2\left(g\right)$
at equilibrium, $2$ mole of $A_2$ are found to be present. The equilibrium constant of the reaction is:

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

Q.

A reversible reaction is one which :

1. Proceeds spontaneously

2. Proceeds in one direction

3. Proceeds in both directions

4. None of the above

Q.

A reversible reaction is one which :

1. Proceeds spontaneously

2. Proceeds in one direction

3. Proceeds in both directions

4. None of the above

Q. The standard Gibbs energy channge at 300 K for the reaction, $2A\rightleftharpoons B+C$ is 2494. 2J. At a given time, the composition of the reaction mixture is $\left[A\right]=\frac{1}{2},\left[B\right]=2$ and $\left[C\right]=\frac{1}{2}.$ The reaction proceeds in the (R = 8.314JK / mol, e = 2.718)

1. forward direction because $Q>K_c$
2. reverse direction because $Q>K_c$
3. forward direction because $Q>K_c$
4. reverse direction because $Q<K_c$