The coefficients in a reaction equation are not necessarily equal to the reactio
ID: 527795 • Letter: T
Question
The coefficients in a reaction equation are not necessarily equal to the reaction orders, whereas the coefficients of an elementary step always equal the reaction orders of its rate law. Explain. A reaction can be thermodynamically favorable, but kinetically unfavourable. What does that mean? When is a reaction thermodynamically or kinetically favorable or unfavorable? Choose a suitable reaction and draw energy diagrams to explain these concepts. For a reaction the following mechanism was proposed: A + B C (fast) C + D rightarrow E (slow) E rightarrow F + B (fast) What is the overall equation? Identify the intermediate(s) and catalyst (s), if any What are the molecularity and the rate law for each step? Is the mechanism consistent with the actual rate law: rate k[A] B][D]?Explanation / Answer
Ans 1.
The number of reacting species in the reaction , taking part in the elimentary reaction which collide simultaneously to bring about a chemical reaction is called as the molecularity of the reaction .
In a complex reaction , that occurs in more than two steps , it is not always necessary that the sum of the coefficients equal to the order of the reaction .
The reaction that may apparently seem as the tenth order reaction might actually be a second order reaction .
The rate of the reaction is determined by the slowest step , which is called as rate determining step.
Hence for elimentary reactions , the molecularity and order can both be same whereas for the complex reactions , molecularity does not make any sense .