Questions tagged [catalysis]

This tag is appropriate for reactions, their mechanisms, their kinetics, when catalysts of any kind are involved.

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0answers
38 views

CuAAC “Click” reaction giving inconsistent results

I apologize in advance for the large amount of text and thank all those who take the time to read it. The "Click" reaction after Fokin and Sharpless is known to achieve high yields without long ...
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28 views

Is activation energy directly related to the reaction rate? (keeping the temperature, concentration, catalyst, particle size and pressure constant)

For different chemical reactions, does the activation energy of that reaction directly relate to the reaction rate? In other words, would a reaction always be slower if it had a higher activation ...
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22 views

Will a Lewis acid catalyze the reaction of HBr with primary alcohols?

It is well-established that a Lewis acid catalyst (popularly $\ce{ZnCl2})$ is necessary to form an alkyl chloride when reacting $\ce{HCl}$ with a primary alcohol. This actually changes the mechanism: ...
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1answer
28 views

How can some enzymes work faster than the diffusion rates of the reactants allow?

Quoting Wikipedia: "Some enzymes operate with kinetics which are faster than diffusion rates, which would seem to be impossible." Which are those enzymes and how can they be so fast? One example is ...
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16 views

Catalyzing the breakdown of Si-O bonds

What catalysts can catalyze the breakdown of (Si-O) bond ? Can you mention some books(ebooks or hard cover) or websites that cover a lot of information about (Si-O) bond characteristics? I have ...
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0answers
23 views

What is the equation that describes the variation in concentration of an inhibitor in an heterogeneous catalysis?

I find myself in quite a pinch: I have to sustain a Chemical Physics exam, and I know for a fact that the professor often asks this particular question: Suppose that we have both a reacting species ...
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0answers
21 views

Why isn't the base reformed in base-catalyzed hydrolysis of esters?

In acid-catalyzed hydrolysis, the hydronium ion is clearly reformed; however, in the base-catalyzed hydrolysis, an alcohol is formed as a by-product, but the strong base isn't reformed. Is it a ...
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2answers
132 views

Rate of reaction graph

An autocatalytic reaction is a reaction in which one of the products catalyses the reaction. In general what will be the shape of curve if the rate of reaction was plotted against time for an ...
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1answer
24 views

Catalysts to accelerate foamy polyurethane reaction

This is the reaction that I am referring to: https://www.youtube.com/watch?v=EoRUSo0BWC0 I am interested in finding catalysts to accelerate this fun chemistry demonstration. I have heard that some ...
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1answer
47 views

Is activation energy time-dependent?

I was thinking lately about activation energy's dependency on time. I couldn't find any information on the internet. Only answer that came up to my mind is the fact that activation energy is constant, ...
4
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1answer
71 views

What is the crystal structure of bismuth oxyhydroxyphosphate (BOHP)?

The recent Chemical & Engineering News article Photocatalyst shreds drinking water contaminant PFOA report the following: Cates and his colleagues made an accidental breakthrough while testing ...
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1answer
77 views

Help with finding the right catalyst and reaction conditions for hydroamination reaction

A friend of mine, final year PhD, and I, final year Bachelor, are focusing on hydroamination reactions. In particular those with secondary amines and substituted alkenes. The reaction in particular is ...
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16 views

Why do electrocatalysts based on polyoxometalates and carbon materials have a weaker activity/performance in acidic media?

I am testing now some doped N and S doped carbon nanomaterials alone and immobilized in POM for the purpose of developing a nanocomposite that can serve as an electrocatalyst for energy-related ...
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19 views

Why do polyoxometalates have good electrochemical/ redox properties?

Many authors are using polyoxomethalates immobilised in carbon nanomaterial as electrocatalysts for energy related reactions (ORR, HER, OER). Other metal alloys have also shown to be successful as ...
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0answers
20 views

What are the reasons that make platinum a good electrocatalyst for oxygen reduction reaction? [duplicate]

Researchers are trying to find new electrocatalysts for energy related reactions in fuel cells in order to replace the expensive platinum-based materials. I would like to know what are exactly the ...
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0answers
32 views

Reactivity of Ni Vs. Pd - available oxidation states

I'm hoping someone can help me tighten up my understanding of the origins of the differences between Ni and Pd catalysis. I understand that Ni has higher charge density and this is the reason for it'...
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21 views

Specific solvents for Wacker-Oxidation

I am currently working on a way to perform a Wacker oxidation of 1-Dodecene into 2-Dodecanone in a continous reaction where it flows through a benchtop NMR, which allows me to monitor the reaction ...
2
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35 views

What is the mechanism of platinum as catalyst poisons on alumina?

I'm wondering if anyone knows by what mechanism is platinum (or other noble metals) catalyst on alumina substrate poisoned? Presently, I'm using platinum on alumina to decompose a hydrogen peroxide / ...
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2answers
95 views

Intuition for why catalyst affects both forward and reverse reactions equally?

I have looked for quite a long time on the site however all the answers involve mathematical explanations involving Arrhenius's equation. I would really like an intuitive reason (or one using ...
2
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0answers
17 views

Metal catalysts used in C-H bond functionalisation [closed]

Why are the late transition metals used for C-H bond activation/functionalisation? What atomic properties of the late TM make them attractive for coordinating C-H sigma bonds? Thanks.
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29 views

Improvement of the thermal stability of hydrous zirconia by post-synthesis treatment with NaOH and NH4OH solutions

I read a paper about how researchers improved the thermal stability of hydrous zirconia by post-synthesis treatment with $\ce{NaOH}$ and $\ce{NH4OH}$.[1] While the surface area of non-treated ...
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2answers
407 views

Using TBAI (tetra-butylammonium iodide) as a catalyst. Ideas on the mechanism or the driving force?

for my etherification of an alcoxide with alkylbromide I used TBAI as a catalyst. The catalyst transfers the alkylbromide into an alkyliodide which is more reactive. I was wondering, what is the ...
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1answer
139 views

Hydrogenation of 1-hexene with Raney nickel

For my high school senior chemistry project, I need to create and perform a lab. I've chosen to do the hydrogenation of 1-hexene with the catalyst of Raney nickel. I'm struggling because I'm not ...
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2answers
297 views

Why isn't iron (III) oxide an effective catalyst for decomposing hydrogen peroxide?

I've been working on a project involving the catalyst iron(III) oxide for decomposing hydrogen peroxide. It barely seemed to produce any oxygen. https://www.youtube.com/watch?v=Ta4DomSDzF8 This video ...
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1answer
166 views

Is it possible to convert methane and carbon dioxide to acetic acid?

Please forgive a bumbling amateur. I have been looking up bond strengths and it seems to me that it should be possible to combine methane with carbon dioxide to make acetic acid: $$\ce{CH4 + CO2 -&...
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38 views

Constraints on rate coefficients in chiral catalytic system

Consider some reversible chemical reaction in a closed system: $$\ce{A <=> B + D} \tag{1}$$ where $\ce{A}$ is some input reagent and $\ce{B}$, $\ce{D}$ are some output reagents. Let's denote ...
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1answer
194 views

How do catalysts provide alternative routes for reactions?

According to collision theory, a reaction will take place between, say, two molecules, if the collision between the atoms has a sufficiently high kinetic energy (to meet the activation energy ...
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58 views

Enantioselective alkylation of Aldehydes by Dialkylzinc reagents

Enantioselective catalysis is one of the important reactions in Organic chemistry which has huge applications in practical basis for synthesis of optically pure natural compounds. In this respect, I ...
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82 views

Why mixture turns brown upon heating, during esterification with H2SO4?

In the lab I was synthesising an ester with sulphuric acid as a catalyst. However the mixture turned brown and my teacher said I had burnt the acid, but what does this actually mean?
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44 views

Meaning of electrochemical vs nonelectrochemical steps

Can someone please explain to me what is meant by an electrochemical reaction step and how it differs from a nonelectrochemical reaction step in the same overall reaction in the context of ...
3
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2answers
776 views

Rate of catalytic hydrogenation of alkenes

What does the rate of catalytic hydrogenation of alkenes depend upon? What'd be the increasing order of rate towards catalytic hydrogenation of the following alkenes, A (2-methylpropene), B (cis-but-2-...
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1answer
104 views

Are there any process and catalyst for convert CO2 and H2O into CH4 and O2 [duplicate]

The equation is simple $$\ce{CO2 + 2 H2O -> CH4 + 2 O2}$$ Yet, is it possible? Are there processes like heat, pressure, electricity, laser and/or any catalyst that could do this process directly? ...
4
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1answer
72 views

Two reactions that catalyze each other [closed]

Is there an example of two reactions that catalyze one another? More than two is also helpful, but I guess it will be hard to find one. By "catalyze one another", I mean that one of the products of ...
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29 views

Application of BET to micropore

'application of the BET equation should be restricted to the range where the term n(1 – p/p0) continuously increases with p/p0'see 5.2.2 in the reference This is one of the criterias IUPAC proposes ...
4
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1answer
327 views

How does calcium chloride act as a sequestrant (food science)?

This Wikipedia page lists common sequestrants (with respect to food science). As stated on the page: A sequestrant forms chelate complexes with polyvalent metal ions, especially copper, iron and ...
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129 views

What happens to promoters or poisons during a catalyzed reaction?

Catalysts are substances that influence reaction rates without undergoing changes in their mass and chemical composition, but may undergo physical changes. Promoters, poison etc. affect the activity ...
3
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1answer
662 views

Catalyst with zero order kinetics

I've read in a book that a catalyst may be included in the rate equation even though it is never used up. It was written as having zero order kinetics however I thought catalyst concentration will ...
2
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1answer
342 views

Catalytic poison in Pt catalysed manufacture of H2SO4

I came across a question that goes as: In manufacturing of sulfuric acid in presence of platinum catalyst, which metal impurity acts as a catalytic poison? Fe Cr Cu V I searched ...
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1answer
194 views

Shift in the position of equilibrium by a catalyst to favor the forward reaction

We were looking at the factors that affect dynamic equilibrium today. The teacher explained how catalysts only affect the rate at which dynamic equilibrium is achieved, and not its position. My ...
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0answers
1k views

What is the annelation effect?

My textbook had this question: Hydrogenation of napthalene with excess hydrogen gas stops cleanly at 1,2,3,4-tetrahydronapthalene. What conclusion can be drawn from this experiment? I observed ...
2
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1answer
2k views

What is the order of the catalytic decomposition of hydrogen peroxide?

I recently did an experiment to determine the activation energy of the decomposition of hydrogen peroxide using iron (III) chloride as a catalyst. I repeated this experiment at different temperatures. ...
2
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1answer
104 views

What causes the anti-siccative effect of soot (amorphous carbon) as a pigment in oil paints?

Oil paint containing carbon black (soot, charcoal) pigment is known to polymerize ("dry") a lot slower than if it has other pigments. I understand this is not just due to the absence of pigments which ...
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1answer
879 views

can a thermodynamically unfavorable reaction be made favorable by a catalyst?

The question i am asking about is pertaining simply to chemical use of a catalyst. It drives a reaction along a different path without taking part chemically. I know this fact. Is it possible so like ...
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46 views

Do catalysts themselves need an input of energy to work?

Do catalysts themselves need an input of energy to work? My book says "catalysts do not per se require an energy source". What does it mean by per se? If they don't use energy how do they activate?
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2answers
829 views

Choice of Lewis Acid for EAS reaction

Why is AlCl3 or FeCl3 might be preferred for chlorination reactions and AlBr3 or FeBr3 for bromination reactions? Why not use AlCl3 for bromination reactions? Source: https://www....
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2answers
622 views

How do I heat my borosilicate reflux column?

I am gonna use a ceramic tape heater, but cannot wrap it around evenly. Is the glass column gonna be okay? I am running some tests on plastic pyrolysis. I am using the reflux condenser to make the ...
4
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1answer
252 views

Why doesn't a catalyst shift the position of equlibrium, when temperature does?

Maybe this is a silly question, but it's not one I've been able to answer to my own satisfaction. Increasing the temperature of a reaction favours the endothermic direction, because it makes it ...
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1answer
352 views

Potential Energy Diagrams and the Effect of Catalysts [closed]

Why does a potential energy diagram showing the effect of a catalyst on activation energy not move left on the reaction pathway scale (compared to uncatalysed reaction) if a catalyst speeds up ...
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0answers
103 views

Role of Lewis acid in synthesis of adamantane from bicyclic species

What is the role of $\ce{AlCl3}$ in the following synthesis of adamantane? I'm guessing it functions as a Lewis acid, but I am unsure how the mechanism of the second step works, as there is no region ...
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64 views

Reaction Kinetics and Catalyst Addition

The addition of a catalyst is known to increase the rate constant of a reaction by providing an easier pathway for the reaction to occur, one with lesser activation energy. My doubt is: Is it ...