Arrhenius Equation

Q.

The time required for $10\%$ completion of a first order reaction at 298 K is equal to that required for its $25\%$ completion at 308K. If the value of A is 4 \times ${10}^{10}{s}^{-1}$. Calculate K at 318 K and $E_a$

Q. Plots showing the variation of the rate constant (k) with temperature (T) are given below. The plot that follows Arrhenius equation is:

1. 
2. 
3. 
4. 

Q.

An increase in the concentration of the reactants of reaction leads to change in:

1. Heat of reaction

2. Threshold energy

3. Collision frequency

4. Activation energy

Q.

The decomposition of hydrocarbon follows the equation $k=(4.5\times {10}^{11}{s}^{-1})e^{-28000}K/T$. Calculate the activation energy $E_a$

Q. A first order reaction is 50% complete in 20 minutes at $27{}^{\circ }C$ and in 5 minutes at $47{}^{\circ }C$. The energy of activation of the reaction is:

1. 11.97 kJ/mol
2. 55.14 kJ/mol
3. ​​​​​​6.65 kJ/mol
4. 43.85 kJ/mol

Q. A first order reaction takes 20 minutes for 25% decomposition. Calculate the time when 75% of the reaction will be completed.
(Given: $log2=0.3010,log3=0.4771,log4=0.6021)$

Q. For a complex reaction $A\stackrel{K}{\to }Products,E_{a_1}=180KJ/mole,E_{a_2}=80KJ/mol,E_{a_3}=50KJ/mol.$ overall rate constant k is related to individual rate constant by the equation $k={\left(\frac{K_1-K_2}{K_3}\right)}^{2/3}.$ Activation energy (KJ/mol) for the overall reaction is

1. 43.44
2. 150
3. 140
4. 100

Q.

The plot of concentration of the reactant R versus time for a reaction is a straight line with a negative slope. The reaction follows a

1. third order rate equation

2. first order rate equation

3. second order rate equation

4. zero order rate equation

Q.

What is the instantaneous Rate of Reaction? How is it determined?

Q. A reaction is 50percent complete in 2 hrs and 75percent complete in 4 hrs. Show that it is a first order reactio

Q. The relation between Boyle’s Temperature T_B and critical temperature T_C is:

1. $2T_B=\frac{8}{27}{T}_C$
2. $T_B=\frac{27}{8}{T}_C$
3. $T_B=\frac{3}{2}{T}_C$
4. $3T_B=\frac{5}{13}{T}_C$

Q. The decomposition of $N_2{O}_5$ according to the equation:
$2N_2{O}_5\left(g\right)\to 4N{O}_2\left(g\right)+O_2\left(g\right)$ is a first order reaction. After $30$ min from the start of the decomposition in a closed vessel, the total pressure developed is found to be $284.5\text{mm}$ of Hg and on complete decomposition, the total pressure is $548.5$ mm of Hg.
$(\log 1.169=0.06)$

1. $\text{Initial pressure of}{N}_2{O}_5=350.80\text{mm of Hg}$
2. Pressure of $N_2{O}_5$ after $30$ min = $200$ mm of Hg
3. Rate constant of the reaction is $10.2\times {10}^{-3}{\text{min}}^{-1}$
4. Rate constant of the reaction is $4.6\times {10}^{-3}{\text{min}}^{-1}$

Q. The rate constant for a zero-order reaction is $2\times {10}^{–2}{\text{mol L}}^{–1}{\text{sec}}^{–1}$, if the concentration of the reactant after $25\text{sec}$ is $0.25M$, calculate the initial concentration.

Q.

The rate constant for the decomposition of hydrocarbons is $2.418\times {10}^{-5}{s}^{-1}$ at 546 K. If the energy of activation is 179.9 kJ/mol, what will be the value of preexponential factor?

Q.

The decomposition of A into product has values of K as $4.5\times {10}^3{s}^{-1}$ at ${10}^{\circ }C$ and energy of activation $60kJmo{l}^{-1}$. At what temperature would K be $1.5\times {10}^4{s}^{-1}$

Q.

The rate constant for a chemical reaction taking place at $500k$ is expressed as $k=A.e^{-1000}$. The activation energy $\left(Ea\right)$ of the reaction is:

1. $100Kcal$

2. $1000Kcal$

3. $10000Kcal$

4. $100000Kcal$

Q.

Time required to decompose SO₂Cl₂ to half of its initial amount is 60 minutes. If the decomposition is a first order reaction, calculate the rate constant of the reaction.

Q. Consider the following cell reaction

$C{d}_{\left(s\right)}+H{g}_{2}S{O}_{4\left(s\right)}+\frac{9}{5}{H}_2{O}_{\left(l\right)}\rightleftharpoons CdS{O}_4.\frac{9}{5}{H}_2{O}_{\left(s\right)}+2H{g}_{\left(l\right)}$

The value of $E_{cell}^0$ is $4.315V$ at ${25}^{0}C$ . If $\Delta H^0=-825.2$
kJ $mo{l}^{-1}$ , the standard entropy change $\Delta S^0$ in $J{K}^{-1}$ is _________ . ( Nearest integer )

$[Given:\text{Faraday constant}=96487Cmo{l}^{-1}]$

Q. Calculate the activation energy of a reaction whose rate constant is tripled by ${10}^{o}C$ rise in the temperature from ${22}^{o}C$.
Take
$ln\left(3\right)=1.1$

1. $46.3kJmo{l}^{-1}$
2. $82.2kJmo{l}^{-1}$
3. $168Jmo{l}^{-1}$
4. $2403Jmo{l}^{-1}$

Q. Consider the following reversible reaction, $A\left(g\right)+B\left(g\right)\rightleftharpoons AB\left(g\right)$.The activation energy of the backward reaction exceeds that of the forward reaction by 2RT $inJmo{l}^{-1}$. If the pre-exponential factor for the forward reaction is 4 times that of the reverse reaction, the absolute value of $\Delta G^{\theta }\left(inJmo{l}^{-1}\right)$ for the reaction at 300 K is.
(Given; ln(2) =0.7, $RT=2500Jmo{l}^{-1}$ at 300 K and G is the Gibbs energy)

Q.

Is that possible to have zero activation energy in a reaction? Explain why?

Q.

During decomposition of an activated complex
(a)energy is always released
(b) energy is always absorbed
(c) energy does not change
(d) reactants may be formed

Q. The rate constant of a reaction becomes equal to the pre-exponential factor at temperature.

1. 0 K
2. infinite
3. 1000 K

Q. 54 In the presence of a catalyst activation energy of a reaction is lowered by 2 kcal at 27 degree celcious.Hence rate will be

Q.

The decomposition of N₂O₅ is first order reaction and represented by

After 15 minutes the volume of O₂ produced is 9 cc and at the end of the reaction 35 cc. The rate constant is equal to

1. 

2. 

3. 

4. 

Q.

In the equation k = Z_AB e^-E_a^/RT, e^-E_a^/RT represents

1. The fraction of molecules with energies equal to or greater than Ea

2. Activation energy

3. Threshold energy

4. Total collisions take place in the reaction

Q. 2. The activation energy for hypothetical reaction A---- products is 12.49 Kcal/mol . if temp is raised from 295 to 305 rate of reaction increases by A)60% B)100% C)50% D)20%

Q. 10. estimate the minimum potential difference needed to reduce Al2O3 at 500 C . the free energy change for decomposition reaction 2/3 Al2O3 -> 4/3 Al + O2 is 960KJ

Q.

Consider the Arrhenius equation given below and mark the correct option.
$k=A.e-\frac{E_a}{RT}$
(a) Rate constant increases exponentially with increasing activation energy and decreasing temperature
(b) Rate constant decreases exponentially with increasing activation energy and decreasing temperature
(c) Rate constant increases exponentially with decreasing activation energy and decreasing temperature
(d) Rate constant increases exponentially with decreasing activation energy and increasing temperature

Q. For a reaction, given below is the graph of $lnk\text{vs}\frac{1}{T}$ . The activation energy for the reaction is equal to $calmo{l}^{-1}$. (Nearest integer)

(Given: $R=2cal{K}^{-1}mo{l}^{-1}$)