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Questions tagged [reaction-mechanism]

The detailed (and as complete as possible) description of plausible or observable pathways leading from reactants to products of a chemical process. This tag should be applied to questions about these processes. It may be applied to hypothetical and/or proposed mechanisms.

Definition (IUPAC goldbook: mechanism of a reaction)

mechanism of a reaction
Synonym: reaction mechanism
A detailed description of the process leading from the reactants to the products of a reaction, including a characterization as complete as possible of the composition, structure, energy and other properties of reaction intermediates, products, and transition states. An acceptable mechanism of a specified reaction (and there may be a number of such alternative mechanisms not excluded by the evidence) must be consistent with the reaction stoichiometry, the rate law and with all other available experimental data, such as the stereochemical course of the reaction. Inferences concerning the electronic motions which dynamically interconvert successive species along the reaction path (as represented by curved arrows, for example) are often included in the description of a mechanism. It should be noted that for many reactions all this information is not available and the suggested mechanism is based on incomplete experimental data. It is not appropriate to use the term mechanism to describe a statement of the probable sequence in a set of stepwise reactions. That should be referred to as a reaction sequence, and not a mechanism.

Related definitions:

Further reading

Aplicability of the tag

This tag should be applied to questions, which seek information on elementary steps of chemical reactions. It may be applied to hypothetical and/or proposed mechanisms.

Related tags

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How exactly does UV light break bonds?

For example, in the photochemical decomposition of hydrogen peroxide, the weak $\ce{O-O}$ bond is broken by UV light. Ultraviolet light can also dissociate relatively strong bonds such as the double oxygen bond ($\ce{O=O}$) in molecular oxygen…
Brian Blumberg
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How to create black precipitate in clear liquid

I am not a chemistry person at all, so my apologies if my question seems dumb. I am working on the set for a short film and in one of the scenes we would like the main actor to look at a sample of water, drop something into it and watch a black…
Petra Rolinec
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Is there a general way to predict products of a chemical reaction

Is there a general way to predict products of a chemical reaction, given only the atomic masses of masses of all elements involved? for example: $\ce{CuFeS2 + O2->}$ $\ce{K2CrO4 + H2SO4->}$ $\ce{FeOCr2O3 + K2CO3 + O2->}$ $\ce{K2Cr2O7 +…
Hashir Omer
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Heating copper wire and sulfur powder

In an experiment in school, we heated copper wire (Cu) and yellow sulfur powder together in a crucible. I was wondering why this reaction cannot produce Copper Sulfate. I know it produces Copper Sulfide but I want to know why don't oxygen from the…
Joe Slater
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Exothermic or Endothermic reactions

Can we determine whether a reaction is endothermic or exothermic? For example if we are given the following reactions: $$\ce{2SO2 + O2 -> 2SO3}$$ $$\ce{H2 + I2 ->2HI}$$ $$\ce{N2 + 3H2 -> 2NH3}$$ Can we determine weather these reactions are…
Rafique
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Common Elemental Termolecular Reactions

Are there any common elemental (single-step) reactions with three reactants? Everything I've found either says that they're very rare, or can be broken down into two bimolecular steps with combined reaction rates far greater than the termolecular…
rmmh
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Why is it necessary to avoid even traces of moisture from a Grignard reagent?

This fact was written in my text book. I wonder why that should be so.
user4972
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Reaction between sulfur and sodium hydroxide

Sulfur reacts with sodium hydroxide in the following way: $\ce{3S + 6NaOH->2Na_2S + Na_2SO_3 + 3H_2O}$ It is a disproportionation reaction: sulfur's oxidation changes from zero to -2 in sodium sulfide and from zero to +4 in sodium sulfite. But how…
CowperKettle
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How is this an autocatalytic reaction?

I'm probably missing a simple component of this reaction, but for some reason I not seeing it. These are two steps that compose a radical process of the Briggs-Rauscher reaction (that are autocatalytic): $IO_3^- + HIO_2+H^+ \rightarrow 2IO_2 \cdot…
Mlagma
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Significance of Proton Tunneling

It has been repeatedly emphasized that proton transfers "involving" three or four membered ring transition states are not favorable and should not be drawn as the primary mechanism for any reaction. However, with regard to a recent discussion…
Dissenter
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What are some ways to predict that a double replacement reaction will occur?

For instance, say: $\ce{2KOH + Pb(NO3)2 -> 2KNO3 + Pb(OH)2}$ How would I even go about beginning to predict this?
Hello
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How can I know the colour change of this reaction?

After you react rotundone ($\ce{C_{15}H_{22}O}$) with water it loses all of the double bonds (except the carboxylic bond, $\ce{C=O}$) and gets two of the functional group $\ce{-OH}$ (alcohol). Two compounds are formed, one (A) where both the alcohol…
ODP
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Diethyl Ether reaction mechanism

I was trying to determine the reaction mechanism behind the production of diethyl ether. Looking at the ethyl alcohol + sulphuric acid method, I have come to the following conclusions for the reaction steps: The ethanol nucleophilic oxygen gets…
jakerz
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Dehydration of methylcyclobutanol

In one of the exams I saw it was written that dehydration of 1-methyl-cyclobutanol yields cyclobutylmethylene (double bond outside the ring) which is the anti Zaitzev product, instead of methylcyclobutene. Why? Thanks!
Neta
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Why doesn't rubidium react with nitrogen gas?

I ran across a problem in which I was asked to predict the result of a reaction between $\ce{Rb}$ and $\ce{N2}$. I was frustrated until I found a note in my textbook which stated that out of all the alkali metals, only $\ce{Li}$ reacts with…
Jephron
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