Single Choice

The rate of the reaction $$H_{2}(g)+Br_{2}(g)\rightarrow 2HBr(g)$$ is given by: $$r=k[H_{2}][Br_{2}]^{1/2}$$ Which among the following is correct?

AOrder of reaction is 2
BMolecularity of reaction is 2
COrder of reaction is 1.5
Correct Answer
DMolecularity of reaction is 2.5

Solution

Molecularity is the number of reacting species (atoms, ions or molecules ) taking part in an elementary reaction.
Since this is not an elementary reaction ( as can be seen from order of reaction) molecularity cannot be predicted until we know the mechanism.
$$H_{2}+Br_{2}\rightarrow 2HBr$$
Order $$=1+\dfrac{1}{2}=\dfrac{3}{2}$$


SIMILAR QUESTIONS

Physical World

Statement - I: For the reaction given below: The molecularity of the first step is 1 and the second step is 2. $$2O_3(g) \rightarrow 3O_2(g)$$ Step 1: $$O_3(g)\rightleftharpoons \, O_2(g) + O(g)$$ Step 2: $$O_3(g) + O \xrightarrow[]{slow} 2O_2(g)$$ Statement - II: O(g) is an intermediate. The rate of reaction is $$K[O_3]^2[O_2]^{-1}$$ and the order of the reaction is 1.

Physical World

Which of the following is/are true :

Physical World

For a reaction; $$X + Y\rightarrow Z, rate \propto [X]$$. What is (i) molecularity and (ii) order of the reaction?

Physical World

For the reaction : $$ 2NH_3 (g) \rightarrow N_2(g) + 3H_2 (g) $$ Rate $$ = k $$ Write the order and molecularity of this reaction .

Physical World

Why is molecularity applicable only for elementary reactions and order is applicable for elementary as well as complex reactions ?

Physical World

What is the difference between the order of a reaction and its molecularity?

Physical World

What is the difference between order of a reaction and the molecularity of a reaction?

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