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Question: Mechanism of a hypothetical reaction \({X_2} + {Y_2} \to 2XY\) is given below: I. \[{X_2} \rightle...

Mechanism of a hypothetical reaction X2+Y22XY{X_2} + {Y_2} \to 2XY is given below:
I. X2X+X{X_2} \rightleftharpoons X + X (Fast)
ii. X+Y2XY+YX + {Y_2} \to XY + Y (slow)
iii. X+YXYX + Y \to XY (Fast)
The overall order of the reaction will be:
A. 1.51.5
B. 11
C. 22
D. 00

Explanation

Solution

Chemical substances do the reaction with each other and form a new product. During the reaction. To become stable every element donates or accepts a pair of electrons. Some reactions are very fast and some are slow.

Complete step by step answer:
Before finding the order of reaction, let's have a look at some point of the chemical reaction.
Hypothetical reaction - A reaction represented by any symbol that is known as the hypothetical reaction. The symbols like A,B,X,YA,B,X,Y , etc.
Fast reaction - A reaction in which reactants react within a time and produce a product is known as a fast reaction.
Slow reaction - A reaction in which the reactant takes time to react is known as a slow reaction.
Here, we have given a hypothetical representation of reaction that is in three steps fast, slow, and fast.
Now, find the order of the reaction.
The rate of reaction is rr =K[x2]a[y2]bK{[{x_2}]^a}{[{y_2}]^b} -equation 1
Now, find the value of a,ba,b.
The rate of reaction is always in the slow step. So, using step 2 that is X+Y2XY+YX + {Y_2} \to XY + Y, so the rate of reaction of this equation.
rr =K[x][y2]K[x][{y_2}] - equation 2
find the rate of reaction in terms of x2{x_2}.
Now, write the Keq{K_{eq}} (equilibrium) of step 1 that is X2X+X{X_2} \rightleftharpoons X + X.
Keq{K_{eq}} =[x][x][x2]\dfrac{{[x][x]}}{{[{x_2}]}} =[x]2[x2]\dfrac{{{{[x]}^2}}}{{[{x_2}]}}
=> [x][x] =(Keq[x2])1/2{({K_{eq}}[{x_2}])^{1/2}}
Now, this value in equation 2.
rr =K(Keq[x2])1/2[y2]1)K{({K_{eq}}[{x_2}])^{1/2}}{[{y_2}]^1})
=K.Keq1/2[x2]1/2[y2]1K.{K_{eq}}^{1/2}{[{x_2}]^{1/2}}{[{y_2}]^1} here, let K.Keq1/2K.{K_{eq}}^{1/2} =KK
so, rr =K[x2]1/2[y2]1K{[{x_2}]^{1/2}}{[{y_2}]^1}
Here, we got the rate of reaction in the format of equation 1, so using the value of a,ba,b . We can find the order of the reaction.
Now, the order of the reaction is 12+1\dfrac{1}{2} + 1 =1.51.5
Therefore, the option AA is the correct answer.

Note:
There are many types of reactions in chemistry. Photochemical reaction - When atom and molecule absorb energy in the form of energy and convert into the excited state. Precipitation - During the chemical reaction, when a solid particle formed in a solution is known as a precipitation reaction.