2.8 Kinetics
Posted by: intechemistry on: September 23, 2010
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5 Responses to "2.8 Kinetics"
April 22, 2011 at 2:46 am
1) An intermediate is often defined a semi-stabilized species, hence it does have a short existence. That description isn’t there for the transition state as the transition state has no measurable existence at all. If it did it would be classified as an intermediate.
2) In a catalysed reaction, a different set of reactions happens which generate the same products and re-generated the catalyst in it’s original form. These ‘different set of reactions’ require lower energy to occur than is the case in the absence of a catalyst.
3) I’ll have to get back to you on that one – I don’t have the book for reference.
May 4, 2012 at 2:58 am
Q : expln why increasing the temp by a small amount has a much bigger effect on the rate of rxn than increasing the pressure by a small amount.
my ans is that becoz temp inc average ke of molecules whereas pressure increased the number of colliding molecules per unit time…
In your opinion,sir how do you think the ans should be worded?
thanx
May 4, 2012 at 12:28 pm
Hummm… Have the Maxwell-Boltzmann distribution diagrams in your mind when you read this:
Increasing pressure does not lead to more molecules having E >= Ea hence the same proportion of molecules from the whole distribution of can only undergo successful collisions per unit time. The vast majority of extra collisions will involve unsuccessful collisions.
However when the temp is raised, a greater proportion of molecules of the whole will now be able to undergo more successful collisions per unit time. Hence the increase in rate is greater with increased temp than with increased pressure.
(that’s an answer in simple terms – not sure it will appear on the final exams though…. but you never know!!(
May 27, 2012 at 8:08 pm
Sir, when the temperature is increased, do the molecules have greater kinetic energy or do more molecules have energy greater than or equal to the activation energy. If both answers are given, which one should be chosen? Thank you sir.
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April 21, 2011 at 8:23 pm
Hey, Sir. I have 3 questions regarding to intermediate and transition state.
1. How true is that to simplify that existence of transition state is very short while intermediate can stay longer due to its stability? I would see that as a way to differentiate them both aside of the technical definition.
2. Catalyst increase by reaction rate by creating alternative routes (via intermediates). Can sir further elaborate on this?
3. Referring to Fig 1.1.21 A2 Chem Pg 24, the x refers to activated complex. Activated complex is the same as transition state. I thought at that level, intermediate is form while transition state is at the peak due to its highly unstable form?
Thanks Sir.