Pseudo first order reaction - class-XII
pseudo first order reaction
Questions
In pseudo unimolecule reactions:
- both the reactants are present in low concentration
- Both the reactants are present in same concentration
- One of the reactant is present in excess
- One of the reactant is non-reactive
The value of rate of a pseudo first order reaction depends upon:
- the concentration of both the reactants present in the reaction
- the concentration of the reactant present in small amount
- the concentration of the reactant present in excess
- the value of $\Delta H$ of the reaction
The value of rate constant of a pseudo first order reaction ________.
- depends on the concentration of reactants present in small amount
- depends on the concentration of reactants present in excess
- is independent of the concentration of reactants
- depends only on temperature
Which of the following is/are correct?
- Acid hydrolysis of an ester follows pseudo first order kinetics
- Inversion of cane sugar follows pseudo first order kinetics
- Decomposition of varous gases on the surface of metallic catalysts, such as decomposition of $HI$ on gold surface also exhibits zero roder kinetics
- Radioactivity follows first order kinetics
Which of the following is pseudo-unimolecular reaction?
- $2{ H } _{ 2 }{ O } _{ 2 }\longrightarrow 2{ H } _{ 2 }O+{ O } _{ 2 }$
- ${ C } _{ 6 }{ H } _{ 5 }{ N } _{ 2 }Cl+HOH\longrightarrow { C } _{ 6 }{ H } _{ 5 }OH+{ N } _{ 2 }+HCl$
- $C{ H } _{ 3 }COO{ C } _{ 2 }{ H } _{ 5 }+NaOH\longrightarrow C{ H } _{ 3 }COONa+{ C } _{ 2 }{ H } _{ 5 }OH$
- $2{ O } _{ 3 }\longrightarrow 3{ O } _{ 2 }$
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?
- Same
- Doubled
- Half
- Data insufficient
A first-order reaction which is $30%$ complete in $30$ minutes has a half-life period of:
- $24.2\ min$
- $58.2\ min$
- $102.2\ min$
- $120.2\ min$
The acid hydrolysis of an ester is___________.
- Pseudo first order reaction
- Bimolecular reaction
- Pseudo unimolecular reactions
- None of the above
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 ______________.
- $12 min$
- $34 min$
- $40 min$
- $43 min$
The acid hydroylsis of ester is:
- first order reaction
- bimolecular reaction
- pseudo unimolecular reaction
- none of the above
Inversion of cane-sugar in dilute acid is a:
- biomolecuar reaction
- pseudo-unimolecular reaction
- unimolecular reaction
- trimolecular reaction
The rate of reaction, $A+B\longrightarrow $ Products, is given by the equation, $r=k\left[ A \right] \left[ B \right] $. If $B$ is taken in large excess, the order of reaction would be:
- $2$
- $1$
- $0$
- Unpredictable
In pseudo-unimolecular reactions:
- one of the reactants is present in large excess
- both the reactants have same concentration
- both the reactants are present in low concentration
- one of the reactants is less reactive
Which of the following are pseudo unimolecular reactions?
- $C{ H } _{ 3 }COO{ C } _{ 2 }{ H } _{ 5 }+HOH\xrightarrow [ ]{ \quad { H }^{ + }\quad } C{ H } _{ 3 }COOH+{ C } _{ 2 }{ H } _{ 5 }OH$
- $C{ H } _{ 3 }COO{ C } _{ 2 }{ H } _{ 5 }+HOH\xrightarrow [ ]{ \quad O{ H }^{ - }\quad } C{ H } _{ 3 }COOH+{ C } _{ 2 }{ H } _{ 5 }OH$
- $\begin{matrix} { C } _{ 12 }{ H } _{ 22 }{ O } _{ 11 } \\ \end{matrix}\begin{matrix} +HOH \\ \end{matrix}\begin{matrix} \xrightarrow [ ]{ \quad { H }^{ + }\quad } \\ \end{matrix}\begin{matrix} { C } _{ 6 }{ H } _{ 12 }{ O } _{ 6 } \\ glucose \end{matrix}\begin{matrix} + \\ \end{matrix}\begin{matrix} { C } _{ 6 }{ H } _{ 12 }{ O } _{ 6 } \\ fructose \end{matrix}$
- $S{ O } _{ 2 }{ Cl } _{ 2 }\left( g \right) \longrightarrow S{ O } _{ 2 }\left( g \right) +{ Cl } _{ 2 }\left( g \right) $
The rate of a first order reaction is $0.04$ mole ${ \ell }^{ -1 }{ S }^{ -1 }$ at $10$ seconds and $0.03$ mol ${ \ell }^{ -1 }{ S }^{ -1 }$ at $20$ seconds after initiation of the reaction. The half-life period of the reaction is:
- $48.1$ s
- $24.1$ s
- $34.1$ s
- $44.1$ s
In a pseudo first order acid catalysed hydrolysis of ester in water the following results were obtained:
t/s 0 30 60 90
[ester]/M 0.55 0.31 0.17 0.085
Which of the following is/are correct for the given reaction?
- The average rate of reaction between time interval 30 to 60 seconds is $4.67\times 10^{-3} mol L^{-1} s^{-1}$
- Order of reaction is 2.
- Pseudo first order rate constant for the acid catalysed hydrolysis of ester is $1.92\times 10^{-2}s^{-1}$
- All are correct.
An optically active compound A upon acid catalysed hydrolysis yield two optically active compound B and C by pseudo first order kinetics. The observed rotation of the mixture after 20 min was $ 20^{\circ}$ while after completion of the reaction it was $-20 ^{\circ} .$ If optical rotation per mole of A,B &C are 60$ ^{\circ} ,40$ $^{\circ}$& $-80 ^{\circ} . $Calculate half life of the reaction.
- 20 min
- 24 min
- 28 min
- 32 min
Which of the following is/are examples of pseudo unimolecular reactions ?
- $\displaystyle CH _3CO _2C _2H _5\, +\, H _2O\, \overset{H^{\oplus}}{\rightarrow}\, CH _3CO _2H\, +\, C _2H _5OH$
- $\displaystyle C _{12}H _{22}O _{11}\, +\, H _2O\, \overset{H^{\oplus}}{\rightarrow}\, \begin{matrix} & C _6H _{12}O _6\\ & (Glucose)\end{matrix}\, =\, \begin{matrix} & C _6H _{12}O _6\\ & (Fructose)\end{matrix}$
- $CH _3COCl\, +\, H _2O\, \rightarrow\, CH _3CO _2H\, +\, HCl$
- $\displaystyle CH _3CO _2C _2H _5\, +\, H _2O\, \overset{OH^{\oplus}}{\rightarrow}\, CH _3CO _2H\, +\, C _2H _5OH$
Consider the reaction represented by the equation represented by the equation
$CH _3Cl(g), +, H _2O(g), \rightarrow, CH _3OH(g), +, HCl(g)$
These kinetic data were obtained for the given reaction concentrations
| Initial conc (M) | Initial conc (M) | Initial rate of disappearance of |
|---|---|---|
| $[CH _3Cl]$ | $[H _2O]$ | $CH _3Cl, (M, s^{-1}$ |
| 0.2 | 0.2 | 1 |
| 0.4 | 0.2 | 2 |
| 0.4 | 0.4 | 8 |
If $H _2O$ is taken in large excess, the order of the reaction will be:
- 1
- 2
- 3
- None of these