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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Apollo on April 12, 2007, 08:28:26 PM

Title: Molecularity and Rate Law
Post by: Apollo on April 12, 2007, 08:28:26 PM
I have a few questions in my chemistry review that I'm not quite sure what they mean. The question asks:

Determine the molecularity and write the rate law for each of these elementary steps:

a) X ---> products

Can someone explain to me what they are asking for?
Title: Re: Molecularity and Rate Law
Post by: polly on April 13, 2007, 04:57:37 AM
Firstly consider the definitions:

An elementary reaction is one that takes place in a single step, which does not involve the formation of any reaction intermediate.

Molecularity of an elementary reaction is a method of classifying the reaction in terms of the number of reactants species that take part

so for your reaction x----> products

it is an elementary reaction because it is a single step, no intermediate formed.
and the molecularity is one (unity) since there is only reactant species (x)

the rate law would then be:

v=k(x)

where k is the first order rate constant and (x) is the concentration of species x.

hope this is a bit clearer now

Title: Re: Molecularity and Rate Law
Post by: Apollo on April 13, 2007, 09:01:26 AM
that makes sense  :) thank you for clearing that up for me