Reversible and Irreversible reaction Questions in English

(B) reversible reaction is a chemical reaction that can proceed in both the forward and backward directions. It eventually attains a state of chemical equilibrium where the rate of the forward reaction equals the rate of the backward reaction,and it never goes to completion.

(C) In a reversible reaction,the reaction proceeds in both forward and backward directions,and therefore,it never proceeds to completion because the reactants are never fully converted into products.

(A) reversible reaction is one that can proceed in both forward and backward directions.
$H_2 + I_2 \rightleftharpoons 2HI$ is a classic example of a reversible reaction.
The other reactions involve the formation of a precipitate ($AgCl$,$BaSO_4$) or a stable product $(FeS)$,which makes them essentially irreversible under standard conditions.

(B) $H_{2} + I_{2} \rightleftharpoons 2HI$ is a reversible reaction when carried out in a closed container as all reactants and products are in the gaseous phase.
$CaCO_{3} \rightleftharpoons CaO + CO_{2}$ is a reversible reaction because the decomposition of $CaCO_{3}$ is an equilibrium process.
$O_{2} + 2SO_{2} \rightleftharpoons 2SO_{3}$ is also a reversible reaction in a closed container as it involves gaseous species.
$AgNO_{3} + NaCl \longrightarrow AgCl + NaNO_{3}$ is an irreversible reaction because $AgCl$ is formed as a white precipitate,which removes the product from the reaction mixture,making the backward reaction impossible.
Therefore,option $B$ is correct.

(A) The thermal decomposition of potassium chlorate $(2KClO_3 \xrightarrow{\Delta} 2KCl + 3O_2)$ is an irreversible reaction.
The law of mass action is applicable only to reversible reactions that reach a state of chemical equilibrium.
Since this reaction proceeds only in the forward direction and does not attain equilibrium,the law of mass action cannot be applied.

(B) Chemical dissociation involves the breaking of chemical bonds to form simpler products,which requires the absorption of energy. Therefore,these reactions are endothermic. Furthermore,many dissociation processes are reversible,reaching a state of equilibrium. Thus,the most accurate description is that they are reversible and endothermic.

(C) As a chemical reaction progresses,the reactants are consumed to form products.
Therefore,the concentration of the reactants decreases over time,while the concentration of the products increases.
Thus,the correct statement is that the concentration of the reactants goes on decreasing.

(B) An irreversible reaction proceeds in only one direction and goes to completion.
In the reaction $AgNO_3 + NaCl \rightarrow AgCl + NaNO_3$,$AgCl$ is formed as a white precipitate.
Because the precipitate is removed from the reaction mixture,the reaction cannot proceed in the reverse direction,making it an irreversible reaction.
The other reactions listed involve gases or equilibrium states that are reversible.

(B) reversible reaction is a chemical reaction that can proceed in both the forward and backward directions.
In such reactions,the products can react to reform the original reactants under the same conditions.
This is represented by a double arrow symbol $( \rightleftharpoons )$.

(A) reversible reaction is a chemical reaction that can proceed in both the forward and backward directions.
Because the reaction can go in both directions,it never reaches $100\%$ completion in a closed system,as the products react to reform the reactants.
Therefore,the correct characteristic is that it never proceeds to completion.

(D) The given reaction involves gaseous reactants and products ($H_2O_{(g)}$ and $H_{2(g)}$).
In an open vessel,the gaseous product $H_2$ escapes into the atmosphere,preventing the reverse reaction from occurring,thus making it an irreversible process.
In a closed vessel,the gaseous products are trapped,allowing the system to reach chemical equilibrium where both forward and backward reactions occur at the same rate.
Therefore,the reaction becomes reversible in a closed vessel.

(N/A) Physical equilibrium refers to a state where the physical state of a substance changes but its chemical composition remains the same,such as $H_2O(s) \rightleftharpoons H_2O(l)$.
Chemical equilibrium refers to a state in a reversible chemical reaction where the rate of the forward reaction equals the rate of the backward reaction,and the concentrations of reactants and products remain constant,such as $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$.
Key differences include:
$1$. Physical equilibrium involves only physical changes,whereas chemical equilibrium involves chemical changes.
$2$. Physical equilibrium is established in physical processes like phase transitions or dissolution,while chemical equilibrium is established in chemical reactions.
$3$. In physical equilibrium,the chemical identity of the species is preserved,whereas in chemical equilibrium,new substances are formed.

(B) When ice is placed in water,the process involves the phase transition between solid ice and liquid water at $0 \ ^\circ C$ (or $273 \ K$).
This is represented as: $H_2O(s) \rightleftharpoons H_2O(l)$.
Since there is no chemical change occurring and only a change in the physical state of the substance,this is an example of physical equilibrium.

(A) Fog is a colloidal system where liquid water droplets are dispersed in air (gas).
This represents a physical state where the liquid phase and the gaseous phase coexist in a state of dynamic equilibrium.
Therefore,it is an example of physical equilibrium.

(N/A)

Homogeneous equilibrium	Heterogeneous equilibrium
$I$. $A$ system in which all the reactants and products are in the same phase is called homogeneous equilibrium.	$I$. $A$ system having more than one phase is called heterogeneous equilibrium.
$II$. In homogeneous reactions,all components are in the gas,aqueous,or liquid phase. Examples: $2HI_{(g)} \rightleftharpoons H_{2(g)} + I_{2(g)}$ $Fe^{3+}_{(aq)} + SCN^{-}_{(aq)} \rightleftharpoons [Fe(SCN)]^{2+}_{(aq)}$ $CH_{3}COOH_{(l)} + C_{2}H_{5}OH_{(l)} \rightleftharpoons CH_{3}COOC_{2}H_{5(l)} + H_{2}O_{(l)}$	$II$. In heterogeneous equilibrium,components exist in different phases (gas,liquid,or solid). Examples: $CaCO_{3(s)} \rightleftharpoons CaO_{(s)} + CO_{2(g)}$ $Ag_{2}O_{(s)} + 2HNO_{3(aq)} \rightleftharpoons 2AgNO_{3(aq)} + H_{2}O_{(l)}$
$III$. All components are included in the expression of the equilibrium constant.	$III$. Pure solids and pure liquids are ignored in the expression of the equilibrium constant.

(A) process is reversible if it occurs in equilibrium,meaning the driving force is infinitesimally small.
$I$. Vaporization of a liquid at its boiling point occurs at constant temperature and pressure where liquid and vapor are in equilibrium. Thus,it is a reversible process.
$II$. Expansion of gas into vacuum is a free expansion,which is irreversible.
$III$. Transformation of a solid substance into liquid at its melting point occurs at constant temperature and pressure where solid and liquid are in equilibrium. Thus,it is a reversible process.
$IV$. Neutralization of an acid by a base is a spontaneous,highly exothermic reaction that proceeds to completion,making it irreversible.
Therefore,$I$ and $III$ are reversible processes.