Catalyst and Catalysis Questions in English

(A) The reaction $SO_{2(g)} + Cl_{2(g)} \rightarrow SO_2Cl_{2(l)}$ is catalyzed by activated charcoal.
This is a classic example of heterogeneous catalysis where charcoal acts as the catalyst.

(D) The catalytic activity is localised on the surface of the catalyst. The mechanism involves five steps:
$(i)$ Diffusion of reactants to the surface of the catalyst.
$(ii)$ Adsorption of reactant molecules on the surface of the catalyst.
$(iii)$ Occurrence of chemical reaction on the catalyst surface,through the formation of an intermediate.
$(iv)$ Desorption of reaction products away from the catalyst surface.
$(v)$ Diffusion of reaction products away from the catalyst surface.
Therefore,the first step is the diffusion of reactants towards the catalyst surface.

(B) catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
In a reversible reaction,a catalyst increases the rates of both the forward and backward reactions to the same extent.
This allows the system to reach the state of equilibrium more quickly.
However,a catalyst does not alter the position of the equilibrium,nor does it change the thermodynamic properties like the energies of reactants and products.
It works by providing an alternative reaction pathway with a lower activation energy.

(C) The statement that nanosized $Cu$ and $Pd$ clusters have less hardness than bulk metal is incorrect.
In reality,nanosized copper and palladium clusters with a diameter in the size range of $5-7 \ nm$ can have hardness up to $500 \%$ greater than the bulk metal due to the Hall-Petch effect.

(A) catalyst provides an alternative reaction pathway with lower activation energy.
It does not affect the potential energy of the reactants or products.
It does not change the equilibrium constant $(K_{eq})$ or the Gibbs free energy change $(\Delta G)$ of the reaction.
Therefore,the statement that the potential energy of reactants and products changes is incorrect.

(D) catalyst is a substance that increases the rate of a chemical reaction by providing an alternative pathway with lower activation energy.
It does not change the thermodynamic properties of the reaction,such as the Gibbs free energy change $(\Delta G)$ or the equilibrium constant $(K_{eq})$.
Therefore,the statement that it increases the free energy change for the reaction is incorrect.

(D) catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
It functions by providing an alternative reaction pathway with a lower $Activation \ energy$ $(E_a)$.
It does not alter the $Gibbs \ energy$ $(\Delta G)$,$Enthalpy$ $(\Delta H)$,or the $Equilibrium \ constant$ $(K_{eq})$ of the reaction.
Therefore,the correct option is $D$.

(D) The Wacker process is an industrial method for the oxidation of ethylene to acetaldehyde.
In this process,$PdCl_2$ (palladium$(II)$ chloride) is used as the primary catalyst,typically in the presence of $CuCl_2$ as a co-catalyst.
Therefore,the correct option is $D$.

(C) In homogeneous catalysis,the reactants and the catalyst are in the same phase.
$(A)$ $2SO_{2(g)} + O_{2(g)} \xrightarrow{Pt_{(s)}} 2SO_{3(g)}$ (Contact process): This is an example of heterogeneous catalysis as the catalyst $(Pt_{(s)})$ is in the solid phase while reactants are in the gaseous phase.
$(B)$ $N_{2(g)} + 3H_{2(g)} \xrightarrow{Fe_{(s)}} 2NH_{3(g)}$ (Haber's process): This is an example of heterogeneous catalysis as the catalyst $(Fe_{(s)})$ is in the solid phase.
$(C)$ $C_{12}H_{22}O_{11(aq)} + H_2O_{(l)} \xrightarrow{HCl_{(aq)}} C_6H_{12}O_{6(aq)} + C_6H_{12}O_{6(aq)}$: Here,the reactant (sucrose) and the catalyst $(HCl_{(aq)})$ are both in the aqueous phase. Thus,it is an example of homogeneous catalysis.
$(D)$ Hydrogenation of oil involves solid catalysts like $Ni_{(s)}$,thus,it is an example of heterogeneous catalysis.

(C) The reaction is $2 SO_{2(g)} + O_{2(g)} \xrightarrow{V_{2}O_{5(s)}} 2 SO_{3(g)}$.
In this reaction,the reactants ($SO_2$ and $O_2$) are in the gaseous phase,while the catalyst $(V_2O_5)$ is in the solid phase.
Since the reactants and the catalyst are in different phases,this is an example of heterogeneous catalysis.

(A) The hydrogenation of vegetable oil involves the reaction of liquid oil with gaseous $H_2$ in the presence of solid $Ni$ catalyst.
Since the catalyst $(Ni)$ is in a solid phase and the reactants (oil and $H_2$) are in liquid/gas phases,the phases are different.
Therefore,this is an example of heterogeneous catalysis.

(A)
$2 SO_{2(g)} + O_{2(g)} \xrightarrow{NO_{(g)}} 2 SO_{3(g)}$
In this reaction,the reactants ($SO_2$ and $O_2$) and the catalyst $(NO)$ are all in the gaseous phase,which defines homogeneous catalysis.

(D) Reactions in $Zeolite$ catalysts are shape-selective in nature.
These reactions depend on the pore structure of the catalyst,the size of the apertures,and the size of the cavities within the $Zeolite$ framework.

(B) Adsorption theory is applicable for solid catalysts which show heterogeneous catalysis.
According to this theory,the gaseous reactants are adsorbed on the surface of the solid catalyst.
As a result,the concentration of the reactants increases on the surface and hence the rate of reaction increases.

(C) Catalytic converters in automobiles use noble metals like $Pt$,$Pd$,and $Rh$ as catalysts to reduce the emission of harmful gases.
These converters facilitate the conversion of toxic gases like carbon monoxide $(CO)$ and nitrogen oxides $(NO_x)$ into less harmful gases like carbon dioxide $(CO_2)$ and nitrogen gas $(N_2)$.
Specifically,the catalyst helps in the reduction of $NO_2$ (a major component of $NO_x$) to $N_2$,preventing its release into the atmosphere.
Therefore,$(X)$ is a metal like $Pt$ or $Pd$ and $(Y)$ is $NO_2$.

(B) In the contact process,sulfur dioxide $(SO_2)$ is oxidized to sulfur trioxide $(SO_3)$ using vanadium pentoxide $(V_2O_5)$ as a catalyst.
In Deacon's process,hydrogen chloride $(HCl)$ is oxidized to chlorine $(Cl_2)$ using copper$(II)$ chloride $(CuCl_2)$ as a catalyst.
Therefore,the correct catalysts are $V_2O_5$ and $CuCl_2$ respectively.

(A) The thermal decomposition of potassium permanganate $(KMnO_4)$ is given by the reaction: $2 KMnO_4 \xrightarrow{\Delta} K_2MnO_4 + MnO_2 + O_2$.
Here,$X$ is manganese dioxide $(MnO_2)$.
$MnO_2$ acts as a catalyst in the decomposition of potassium chlorate $(KClO_3)$ to produce oxygen gas.
The reaction is: $2 KClO_3 \xrightarrow{MnO_2, \Delta} 2 KCl + 3 O_2$.
Therefore,the correct option is $A$.

(A) Ethene reacts with oxygen in the presence of palladium$(II)$ chloride as a catalyst to form acetaldehyde.
This process is known as the Wacker process.
The chemical reaction is: $CH_2=CH_2 + \frac{1}{2}O_2 \xrightarrow{Pd(II), Cu(II)} CH_3CHO$.

(C) The correct matches are:
$A$. $N_{2(g)} + 3H_{2(g)} \longrightarrow 2NH_{3(g)}$ uses $Fe$ as a catalyst (Haber process) $(IV)$.
$B$. $2H_{2(g)} + O_{2(g)} \longrightarrow 2H_2O_{(l)}$ uses $Pt$ as a catalyst $(II)$.
$C$. $CO_{(g)} + 3H_{2(g)} \longrightarrow CH_{4(g)} + H_2O_{(g)}$ uses $Ni$ as a catalyst $(I)$.
$D$. $CO_{(g)} + 2H_{2(g)} \longrightarrow CH_3OH_{(g)}$ uses $ZnO-Cr_2O_3$ as a catalyst $(III)$.
Thus,the correct sequence is $A-IV, B-II, C-I, D-III$.

(A) The correct matches are:
$A$. Ostwald's process uses $Pt/Rh$ gauge as a catalyst.
$B$. Lead Chamber process uses $NO$ as a catalyst.
$C$. Deacon's process uses $CuCl_2$ as a catalyst.
$D$. Haber's process uses $Fe$ as a catalyst.
Therefore,the correct sequence is $A-III, B-I, C-IV, D-II$.

(C) In the hydrogenation of vegetable oil,the reactants and catalyst exist in three different states.
Vegetable oil is a liquid (reactant),hydrogen is a gas (reactant),and the catalyst (typically nickel,$Ni$) is a solid.
Thus,the system involves three distinct physical states.

(D) The reaction between $KMnO_4$ and oxalic acid $(H_2C_2O_4)$ in the presence of dilute $H_2SO_4$ is given by the equation:
$2KMnO_4 + 3H_2SO_4 + 5H_2C_2O_4 \rightarrow K_2SO_4 + 2MnSO_4 + 8H_2O + 10CO_2$.
In this reaction,$Mn^{2+}$ ions are produced as a product.
These $Mn^{2+}$ ions act as an autocatalyst,meaning they increase the rate of the reaction as the reaction proceeds.
Therefore,$MnSO_4$ (which provides $Mn^{2+}$ ions) acts as the autocatalyst.

(D) Zeolites are aluminosilicates with a three-dimensional network structure. Statement $(I)$ is correct as they are shape-selective catalysts due to their pore structure.
Statement $(II)$ is correct as they possess an $Al-O-Si$ framework.
Statement $(III)$ is incorrect because zeolites are found in nature as minerals and can also be synthesized.
Statement $(IV)$ is correct as they are widely used in the petrochemical industry for cracking hydrocarbons and isomerization.
Therefore,statements $(I)$,$(II)$,and $(IV)$ are correct.

(B) The adsorption theory of catalysis explains the mechanism of $Heterogeneous \ catalysis$.
According to this theory,the reactant molecules are adsorbed on the surface of the solid catalyst,which increases the concentration of reactants on the surface and facilitates the formation of an intermediate,thereby lowering the activation energy of the reaction.

(C) In heterogeneous catalysis,the reactants and the catalyst are in different phases.
$(A)$ Ammonia synthesis $(N_2(g) + 3H_2(g) \xrightarrow{Fe(s)} 2NH_3(g))$ involves gaseous reactants and a solid catalyst.
$(B)$ Lead chamber process $(2SO_2(g) + O_2(g) \xrightarrow{NO(g)} 2SO_3(g))$ is a homogeneous reaction.
$(C)$ Hydrogenation of vegetable oils $(R-CH=CH-R(l) + H_2(g) \xrightarrow{Ni(s)} R-CH_2-CH_2-R(s))$ involves liquid and gaseous reactants with a solid catalyst.
$(D)$ Hydrolysis of methyl acetate $(CH_3COOCH_3(l) + H_2O(l) \xrightarrow{H^+(aq)} CH_3COOH(aq) + CH_3OH(aq))$ is a homogeneous reaction.
Both $(A)$ and $(C)$ represent heterogeneous catalysis. However,in the context of standard chemistry problems,the hydrogenation of vegetable oils is the classic example of heterogeneous catalysis involving different phases of reactants (liquid oil and gaseous hydrogen).

(C) According to the adsorption theory of heterogeneous catalysis,the mechanism involves the following steps:
$1$. Diffusion of reactants to the surface of the catalyst.
$2$. Adsorption of reactant molecules on the surface of the catalyst.
$3$. Occurrence of a chemical reaction on the catalyst surface through the formation of an intermediate.
$4$. Desorption of product molecules from the surface,thereby making the surface available again for more reaction.
$5$. Diffusion of reaction products away from the surface.
Since the product molecules must desorb to free the surface for further reaction,the statement that product molecules remain permanently bound to the catalyst surface is incorrect.

(B) The correct matches are as follows:
$A$. Hydrogenation of vegetable oils uses $Ni$ as a catalyst $(A-I)$.
$B$. Decomposition of potassium chlorate $(2KClO_3 \rightarrow 2KCl + 3O_2)$ uses $MnO_2$ as a catalyst $(B-II)$.
$C$. Oxidation of $SO_2$ in the lead chamber process uses $NO_{(g)}$ as a catalyst $(C-IV)$.
$D$. Oxidation of ammonia in Ostwald's process uses $Pt$ as a catalyst $(D-III)$.
Therefore,the correct sequence is $A-I, B-II, C-IV, D-III$.

(C) In heterogeneous catalysis,the physical state of the catalyst is different from the physical state of the reactants.
In option $C$,the reactants $A$ and $B$ are in the gaseous state $(g)$,while the catalyst $C$ is in the solid state $(s)$.
Therefore,this reaction represents heterogeneous catalysis.

(C) catalyst provides an alternative reaction pathway with a lower activation energy.
This increases the rate of both the forward and backward reactions equally,thereby shortening the time required to reach chemical equilibrium without altering the equilibrium position or the equilibrium constant.

(D) In Haber's process for the manufacture of ammonia,the catalyst used is finely divided $Fe$,the promoter used is $Mo$ (or $K_2O$ and $Al_2O_3$),and the poison for the catalyst is $CO$.

(A) The correct matches are as follows:
$A$. Ostwald's process uses $Pt$ gauge as a catalyst $(A-III)$.
$B$. Haber's process uses $Fe$ as a catalyst $(B-IV)$.
$C$. Deacon's process uses $CuCl_2$ as a catalyst $(C-I)$.
$D$. Cracking of hydrocarbons uses Zeolites as a catalyst $(D-II)$.
Therefore,the correct sequence is $A-III, B-IV, C-I, D-II$.

(C) In the Haber's process for the synthesis of ammonia from $N_2$ and $H_2$,$Fe$ is used as a catalyst and $Mo$ acts as a promoter (activator).
The chemical equation is: $N_{2(g)} + 3H_{2(g)} \rightleftharpoons[Mo]{Fe} 2NH_{3(g)} + 22.4 \text{ kcal}$.

(D) In the contact process for the manufacture of sulfuric acid $(H_2SO_4)$,the sulfur dioxide $(SO_2)$ gas obtained from burning sulfur or roasting sulfide ores contains impurities like arsenic compounds.
These impurities act as catalytic poisons for the platinum catalyst used in the converter.
To remove these arsenic impurities,an arsenic purifier is used.
The arsenic purifier contains ferric oxide $(Fe_2O_3 \cdot xH_2O)$,which effectively adsorbs the arsenic impurities from the gas stream.

(A) The catalysts for the given reactions are as follows:
$(I)$ Acidic hydrolysis of ester uses a strong acid like $HCl$ as a catalyst.
$(II)$ The Contact process for the oxidation of $SO_2$ to $SO_3$ uses $Pt_{(s)}$ or $V_2O_5$ as a catalyst.
$(III)$ The Lead Chamber process for the oxidation of $SO_2$ to $SO_3$ uses $NO_{(g)}$ as a catalyst.
$(IV)$ The Haber process for the synthesis of $NH_3$ uses $Fe_{(s)}$ as a catalyst.
Therefore,the correct sequence is $HCl_{(l)}, Pt_{(s)}, NO_{(g)}$ and $Fe_{(s)}$.

(D) An auto-catalytic reaction is one in which one of the products formed acts as a catalyst for the reaction itself.
In the reaction between oxalate ions and permanganate ions:
$5C_2O_4^{2-} + 2MnO_4^{-} + 16H^{+} \longrightarrow 10CO_2 + 2Mn^{2+} + 8H_2O$
The $Mn^{2+}$ ions produced in the reaction act as an auto-catalyst,significantly increasing the rate of the reaction as the concentration of $Mn^{2+}$ increases.
Therefore,option $(D)$ is the correct answer.

(C) In a heterogeneous catalysis reaction,the catalyst and the reactants exist in different phases.
In the reaction $2 H_2 O_{2(l)} \xrightarrow{Pt_{(s)}} 2 H_2 O_{(l)} + O_{2(g)}$,the reactant $H_2 O_2$ is in the liquid phase $(l)$ while the catalyst $Pt$ is in the solid phase $(s)$.
Since they are in different phases,this is an example of heterogeneous catalysis.

(C) Heterogeneous catalysis is a process where the catalyst exists in a different phase from the reactants.
In the reaction $2 CO_{(g)} + O_{2(g)} \xrightarrow{Pt_{(s)}} 2 CO_{2(g)}$,the reactants ($CO$ and $O_2$) are in the gaseous phase,while the catalyst $(Pt)$ is in the solid phase.
Since the phases are different,this is an example of heterogeneous catalysis.

(C) In the Haber's process for the synthesis of $NH_3$,$Fe$ is used as the catalyst.
$Mo$ was used as a promoter in earlier industrial processes.
Currently,a mixture of $K_2O$ and $Al_2O_3$ is used as the promoter to increase the efficiency of the catalyst.

(D) The Wacker process involves the oxidation of ethylene to acetaldehyde using oxygen in the presence of a palladium$(II)$ chloride $(PdCl_2)$ catalyst and a copper$(II)$ chloride $(CuCl_2)$ co-catalyst.
The chemical equation for the reaction is: $C_2H_4 + \frac{1}{2}O_2 \xrightarrow{PdCl_2, CuCl_2} CH_3CHO$.
Thus,$PdCl_2$ acts as the primary catalyst in this industrial process.