Tag: chemical kinetics

Questions Related to chemical kinetics

The value of rate constant of a pseudo first order reaction ________.

pseudo first order reaction order of reactions chemical kinetics electrochemistry and chemical kinetics chemistry

  1. depends on the concentration of reactants present in small amount

  2. depends on the concentration of reactants present in excess

  3. is independent of the concentration of reactants

  4. depends only on temperature

Show answer
Correct Option: B
Explanation:

Pseudo first-order reaction is not the first-order reaction by nature. It is made the first order by adding something in excess.so, the rate constant depends on the concentration of reactants present in excess.

Which of the following is/are correct?

pseudo first order reaction order of reactions chemical kinetics electrochemistry and chemical kinetics chemistry

  1. Acid hydrolysis of an ester follows pseudo first order kinetics

  2. Inversion of cane sugar follows pseudo first order kinetics

  3. Decomposition of varous gases on the surface of metallic catalysts, such as decomposition of $HI$ on gold surface also exhibits zero roder kinetics

  4. Radioactivity follows first order kinetics

Show answer
Correct Option: A,B,C,D
Explanation:

 Pseudo first order reaction is a reaction in which concentration of one of the species dominates over the other. Hence the reaction follows the first order kinetics.

Options A, B and C all are the examples of pseudo first order reaction.
Radioactive decay follows first order reaction.

$\mathbf {Hence\ all\ the\ options\ are\ correct.}$

Nitrosy ligand binds to d-metal atoms in liner and bent fashion and behaves, respectively, as _______________.

pseudo first order reaction order of reactions chemical kinetics electrochemistry and chemical kinetics chemistry

  1. $NO^{+}$ and $NO^{+}$

  2. $NO^{+}$ and $NO^{-}$

  3. $NO^{-}$ and $NO^{-}$

  4. $NO^{-}$ and $NO^{+}$

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Correct Option: B

Triple point temperature for water is nearly:

pseudo first order reaction order of reactions chemical kinetics electrochemistry and chemical kinetics chemistry

  1. $273.16K$

  2. $373.16K$

  3. ${100}^{o}C$

  4. ${444.6}^{o}C$

Show answer
Correct Option: A
Explanation:

Triple point temperature for water is nearly $0.01^{o} \ C$, which is $273.16 \ K$.

Hence, option A is correct.

Which of the following is pseudo-unimolecular reaction?

pseudo first order reaction order of reactions chemical kinetics electrochemistry and chemical kinetics chemistry

  1. $2{ H } _{ 2 }{ O } _{ 2 }\longrightarrow 2{ H } _{ 2 }O+{ O } _{ 2 }$

  2. ${ C } _{ 6 }{ H } _{ 5 }{ N } _{ 2 }Cl+HOH\longrightarrow { C } _{ 6 }{ H } _{ 5 }OH+{ N } _{ 2 }+HCl$

  3. $C{ H } _{ 3 }COO{ C } _{ 2 }{ H } _{ 5 }+NaOH\longrightarrow C{ H } _{ 3 }COONa+{ C } _{ 2 }{ H } _{ 5 }OH$

  4. $2{ O } _{ 3 }\longrightarrow 3{ O } _{ 2 }$

Show answer
Correct Option: B
Explanation:

In a chemical reaction if two or more reactants are involved but the rate of reaction depends only upon the concentration of one of the reactant and independent of other reactants then it is said to be a pseudo unimolecular reaction.

so the option B shows the pseudotype of reaction 

Rate law for the following reaction; $Ester+H^+\rightleftharpoons Acids+ Alcohol$; is $\frac {dx}{dt}=k [ester]^1 [H^+]^0$. What would be the effect on the rate if concentration of $H^+$ ion is doubled?

pseudo first order reaction order of reactions chemical kinetics electrochemistry and chemical kinetics chemistry

  1. Same

  2. Doubled

  3. Half

  4. Data insufficient

Show answer
Correct Option: A
Explanation:

As reaction does not depend on the concentration of $H^+$, therefore, rate will be the same.

A first-order reaction which is $30\%$ complete in $30$ minutes has a half-life period of:

pseudo first order reaction order of reactions chemical kinetics electrochemistry and chemical kinetics chemistry

  1. $24.2\ min$

  2. $58.2\ min$

  3. $102.2\ min$

  4. $120.2\ min$

Show answer
Correct Option: B
Explanation:

It is a 1st order reaction


$k = \dfrac{2.303}{t} log \dfrac{a}{a-x}$

but $k=\dfrac{0.693}{t _{\frac{1}{2}}}$

$\dfrac{0.693}{{t} _{1/2}} = \dfrac{2.303}{30} log \dfrac{100}{70}$

${t} _{1/2} = 58.2 min$

Hence, the correct option is $B$

The acid hydrolysis of an ester is___________.

pseudo first order reaction order of reactions chemical kinetics electrochemistry and chemical kinetics chemistry

  1. Pseudo first order reaction

  2. Bimolecular reaction

  3. Pseudo unimolecular reactions

  4. None of the above

Show answer
Correct Option: A,C

In a first order reaction $A \rightarrow B, 60\%$ of the given sample of compounds decomposes in $45$ minutes. The half life of the reaction is ______________.

pseudo first order reaction order of reactions chemical kinetics electrochemistry and chemical kinetics chemistry

  1. $12 min$

  2. $34 min$

  3. $40 min$

  4. $43 min$

Show answer
Correct Option: C

The acid hydroylsis of ester is:

pseudo first order reaction order of reactions chemical kinetics electrochemistry and chemical kinetics chemistry

  1. first order reaction

  2. bimolecular reaction

  3. pseudo unimolecular reaction

  4. none of the above

Show answer
Correct Option: A,B,C
Explanation:

The acid hydrolysis of ester is a first-order reaction, bimolecular reaction and pseudo unimolecular reaction.


When an ester (such as ethyl acetate) is mixed with water it is converted into alcohol and acid according to the following equation: 

$CH _3COOC _2H _5 + H _2O \rightarrow CH _3COOH + C _2H _5OH$

When the amount of water is relatively large, the reaction goes practically to completion (the equilibrium shifts to the right) and the rate is first order with respect to the ester. The hydrolysis takes place slowly with pure water and is catalyzed by acids.

Hence, options A, B and C are correct.