Which of the following statements is FALSE? In order for a reaction to occur, re
ID: 564062 • Letter: W
Question
Which of the following statements is FALSE?
In order for a reaction to occur, reactant molecules must collide.
The rate of the bimolecular reaction A + B products is proportional to the frequency of collisions between A and B.
The transition state is a short-lived, high energy state, intermediate between reactants and products.
A catalyst alters the rate of a reaction and is neither a product nor a reactant in the overall equation.
A reaction of the form, 2 A + B products, will usually have a one-step mechanism.
a.In order for a reaction to occur, reactant molecules must collide.
b.The rate of the bimolecular reaction A + B products is proportional to the frequency of collisions between A and B.
c.The transition state is a short-lived, high energy state, intermediate between reactants and products.
d.A catalyst alters the rate of a reaction and is neither a product nor a reactant in the overall equation.
e.A reaction of the form, 2 A + B products, will usually have a one-step mechanism.
Explanation / Answer
(a) As per the kinetic molecular theory of gases, gas molecules must collide among themselves. These collisions lead to the formation of new molecules (product molecules) and hence, statement (a) is correct.
(b) A chemical reaction takes place when the reactant molecules collide. How fast or slow the reactant molecules collide determines the rate of the reaction. Therefore, the rate of the reaction is directly proportional to the frequency of collisions of the reactant molecules. Hence, statement (b) is correct.
(c) The transition state is formed by rearrangement of the reactant molecules and decomposes to form the products. The transition state has a higher energy than the reactants and the products (hence, it breaks down to form the products). The transition state is rarely isolated from the reaction mixture; hence, it is short-lived. Therefore, (c) is a correct statement.
(d) A catalyst is a chemical entity that alters the rate of a reaction. In general, a catalyst speeds up a very slow reaction or slows down a very fast reaction (that is acts as an inhibitor). The catalyst is recovered at the end of the reaction, hence, it is neither a reactant nor a product. Therefore, statement (d) is correct.
(e) is a false statement. The reactants A and B may react to form the products in a single step; however, a mechanism may be possible where on molecule, each of A and B react to form an intermediate (say C) and the intermediate then reacts with a second molecule of A to form the products. Another mechanism may lead to formation of an intermediate (say D) by combining two molecules of A and this intermediate reacts with B to form the products. Hence, (e) is false.
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