billybob
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Catalysts!
What do you think would happen to the reaction if a catalyst was removed from a reaction? Will the reaction keep going? What are your thoughts?
I believe that if a catalyst is removed from a reactions, it will not go fast anymore. It will go slow instead. Am I correct?
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byko3y
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Yes, you are. This is a definition of catalyst.
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j_sum1
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Yep.
Although that Wikipedia article is one of those really badly written ones.
| Quote: | | With a catalyst, reactions occur faster and with less energy. |
This is the sort of concept-muddling stuff
that is not needed.
Anyone have a good reference off the top of their head for billibob?
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greenlight
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"Catalysis is an acceleration or retardation of the rate of a chemical reaction, brought about by the addition of a substance (the catalyst ) to
the reaction medium. The catalyst, usually present in small amounts, is not consumed in the reaction. Catalysis today is almost always associated with
rate acceleration, and is very important in industry because rate acceleration usually means that a chemical compound can be made more cheaply and
cleanly."
"What does a catalyst do? First of all, a catalyst does not change the energetic characteristics of the reactants and products and the barriers
between them. It instead finds an alternate reaction pathway that bridges reactants and products, and one that has lower (and thus easier-to-traverse)
energy barriers. An alternate pathway means a faster reaction rate. Although a catalyst can itself be considered a reactant, it is regenerated,
unchanged, at a later stage in the catalytic process. The regenerated catalyst can then be used to catalyze another like reaction. Thus, in principle,
only a very small amount of catalyst is needed to generate copious amounts of product"
Read more: http://www.chemistryexplained.com/Bo-Ce/Catalysis-and-Catalysts.html
[Edited on 2-6-2015 by greenlight]
[Edited on 2-6-2015 by greenlight]
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phlogiston
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| Quote: | What does a catalyst do? First of all, a catalyst does not change the energetic characteristics of the reactants and products and the barriers between
them.
…..snip….
It instead finds an alternate reaction pathway |
This is debatable. Many catalysts work by lowering the energy of an intermediate state (‘activation energy’) or by bringing reactants together
under more optimal local conditions.
Many enzymes for instance work by providing a better relative orientation of the reactants, or via stabilization of an intermediate reaction state by
providing the right electrostatic interactions in the local environment.
Most people would not call that an 'alternative mechanism' or 'alternative reaction pathway'.
The simple definition that ‘a catalyst is a substance that speeds up a reaction but is not consumed by it’ covers most situations well.
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"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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