Law of Mass Action

Q. Under a given set of experimental conditions, with increase in the concentration of the reactants, the rate of a chemical reaction________for positive order reactions.

1. Decreases
2. Increases
3. Remains unaltered
4. First fecreases and then increases

Q.

NX is produced by the following step of reactions M + $X_2$$⟶$$M{X}_2$$⟶$$M{X}_2$+$X_2$$⟶$$M_3{X}_8$

$M_3{X}_8$+$N_{2}C{O}_3$$⟶$NX +$C{O}_2$+$M_3{O}_4$ How much M (metal) is consumed to produce 206 gm of NX. (Take at wt. of M = 56, N = 23, X = 80)

1. 42 g

2. 56 g

3. $\frac{14}{3}g$

4. $\frac{7}{4}g$

Q. Define law of mass action with mathematical derivation

Q.

NX is produced by the following step of reactions M + $X_2$$⟶$$M{X}_2$$⟶$$M{X}_2$+$X_2$$⟶$$M_3{X}_8$ $M_3{X}_8$+$N_{2}C{O}_3$$⟶$NX +$C{O}_2$+$M_3{O}_4$ How much M (metal) is consumed to produce 206 gm of NX. (Take at wt. of M = 56, N = 23, X = 80)

1. 

2. 

3. 56 g

4. 42 g

Q. The following concentration were obtained for the formation of $N{H}_3$ form $N_2$ and $H_2$ at equilibrium for the reaction $N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$

$\left[N_2\right]=1.5\times {10}^{-2}M$
$\left[H_2\right]=3.0\times {10}^{-2}M$
$\left[N{H}_3\right]=1.2\times {10}^{-2}M$

Calculate equilibrium constant.

1. $310.0$
2. $536.0$
3. $556.0$
4. $356.0$

Q. $2X\left(g\right)+3Y\left(g\right)+Z\left(g\right)\to P\left(g\right)+Q\left(g\right)$
The order of the given reaction is $\frac{3}{4}$ and the experimental rate law of the given reaction is $K\left[X{]}^{\frac{1}{2}}\right[Y{]}^{\frac{3}{4}}[Z{]}^a$. Find the order of reaction with respect to Z.

1. $\frac{-1}{2}$
2. $0$
3. $\frac{1}{2}$
4. $1$

Q. Write the unit of equilibrium constant $\left(K_c\right)$ for the given reaction.
$C\left(s\right)+\frac{1}{2}{O}_2\left(g\right)\to C{O}_2\left(g\right)$

1. $(mol/L{)}^{\frac{3}{2}}$
2. $\left(mol/L\right)$
3. $(mol/L{)}^{\frac{-1}{2}}$
4. $(mol/L{)}^{\frac{1}{2}}$

Q. For, $Zn\left(s\right)+2HCl\left(aq\right)\rightleftharpoons ZnC{l}_2\left(aq\right)+H_2\left(g\right)$
what will be the expression of $K_c$:

1. $K_c$ = $\left[H_2\right]$
2. $K_c$ = $\frac{\left[H_2\right]\left[ZnC{l}_2\right]}{[HCl{]}^2}$
3. $K_c$ = $\frac{\left[H_2\right]}{\left[HCl\right]}$
4. $K_c$ = $\frac{\left[H_2\right]\left[ZnC{l}_2\right]}{\left[HCl\right]\left[Zn\right]}$

Q.

For a given reversible reaction if the concentrations of the reactants are quadrupled, the equilibrium constant will be

1. be quadrupled

2. be one fourth of the previous value

3. remain the same

4. be halved

Q. In the thermal decomposition of potassium chlorate given as $2KCl{O}_3\left(s\right)\to 2KCl\left(s\right)+3O_2\left(g\right)$,
The law of mass action :

1. Cannot be applied
2. Can be applied
3. Can be applied at high temperature
4. Can be applied at low temperature and pressure

Q. The following concentration were obtained for the formation of $N{H}_3$ form $N_2$ and $H_2$ at equilibrium for the reaction $N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$

$\left[N_2\right]=1.5\times {10}^{-2}M$
$\left[H_2\right]=3.0\times {10}^{-2}M$
$\left[N{H}_3\right]=1.2\times {10}^{-2}M$

Calculate equilibrium constant.

1. $310.0$
2. $536.0$
3. $556.0$
4. $356.0$

Q. Identify the equilibrium reaction in which $K_C$ has no units.

1. All of the above
2. Decomposition of $PC{l}_5$
3. Decomposition of $HI$
4. Decomposition of $N{H}_3$

Q. Equation for the reaction when compound $A$ is bubbled through bromine dissolved in carbon tetrachloride is as follows :
$A\underrightarrow{B{r}_2/C{Cl}_4}\begin{array}{c}C{H}_{2}Br\\ |\\ C{H}_{2}Br\end{array}$
(i) Draw the structure of $A$.
(ii) State your observation during this reaction.

Q. The rate law for reaction b/w A and B is given by rate = k[A]m[B]n on doubling the concentration of A and halving the concentration of B , THE ratio the new rate to the earlier rate of reaction will be as

Q. For the chemical reaction $N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$ the correct option is :

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Q.

Why the reaction is endothermic in the figure shown below?

1. Because product is at lower energy than reactant

2. Because product is at same energy as reactant

3. None of the these

4. Because product is at higher energy than reactant

Q. Draw the energy profile diagram of SN1 reaction.

Q.

The law of mass action was proposed by:

1. Guldberg and Waage

2. Kossel and Lewis

3. Van’t Hoff

4. Le Chatelier and Braun

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

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

Q. Under a given set of experimental conditions, with increase in the concentration of the reactants, the rate of a chemical reaction________for positive order reactions.

1. Decreases
2. Increases
3. Remains unaltered
4. First fecreases and then increases

Q. $NO$ and $B{r}_2$ at initial partial pressures of 98.4 and 41.3 $\text{torr}$, respectively, were allowed to react at $300\text{K}$. At equilibrium the total pressure was $110.5\text{torr}$. Calculate the value of the equilibrium constant ($Kp$) at $300\text{K}$, for the reaction $2NO\left(g\right)+B{r}_2\left(g\right)\rightleftharpoons 2NOBr\left(g\right).$

1. $134at{m}^{-1}$
2. $164at{m}^{-1}$
3. $234at{m}^{-1}$
4. $264at{m}^{-1}$

Q.

The equilibrium expression, K = [Ag⁺][Cl^–] describes the reaction:

1. AgCl → Ag⁺ + Cl¯

2. Ag⁺ + Cl¯ → AgCl

3. Ag⁺ + Cl¯ → Ag + Cl

4. Ag + Cl → Ag⁺ + Cl¯

Q. Which is false about the equilibrium N2 + 3H2 ⇌ 2NH3 + x kJ ?

• a On raising the temperature, yield of NH3 is reduced
• b On adding inert gas at constant pressure, the yield of NH3 is reduced
• c On adding inert gas at constant volume, the yield of NH3 is increased
• d On increasing the pressure, yield of NH3 is increased
• e On increasing the concentrations of N2 and H2 yield of NH3 is increased

Q. The law of mass action states that at a constant temperature, the rate of a chemical reaction is proportional to the _____ of the reacting substances.

1. total mass
2. molecular weights
3. active masses
4. None of these

Q. The vapor density of completely dissociated $N{H}_{4}Cl$ would be

1. same as that of $N{H}_{4}Cl$
2. double than that of $N{H}_{4}Cl$
3. half than that of $N{H}_{4}Cl$
4. slightly less than that of $N{H}_{4}Cl$

Q.

The active mass of a solid is taken to be unity - true or false?

1. True

2. False

Q. Write the expression for the equilibrium constant, $K_c$ for each of the following reactions.
(i) $2NOCl\left(g\right)\rightleftharpoons 2NO\left(g\right)+{Cl}_2\left(g\right)$
(ii) ${2Cu\left({NO}_3\right)}_2\left(s\right)\rightleftharpoons 2CuO\left(s\right)+4{NO}_2\left(g\right)+O_2\left(g\right)$
(iii) ${CH}_3{COOC}_2{H}_5\left(aq\right)+H_{2}O\left(1\right)\rightleftharpoons {CH}_{3}COOH\left(aq\right)+C_2{H}_{5}OH\left(aq\right)$
(iv) ${Fe}^{3+}\left(aq\right)+3{OH}^{-}\left(aq\right)\rightleftharpoons {Fe\left(OH\right)}_3\left(s\right)$
(v) $I_2\left(s\right)+5F_2\rightleftharpoons 2I{F}_5$