Questions tagged [reaction-control]

Questions related to the chemical and physical influences that influence the rate and probability of chemical reactions. Not to be confused with [catalysis] or [reaction-mechanism].

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What's the difference between “conversion” in condensation polymerization and in radical polymerization?

The conversion in condensation polymerization is defined as the fraction of functional groups reacted, $$p=\frac{[M]_0-M}{[M]_0}$$ while in radical polymerization it's defined as the fraction of ...
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Can there be gaps in autoignition temperatures?

I recently saw a request for solids that auto-ignite between 80C and 160C. I can't find any, and none have yet been suggested. Which leads me to the theoretical question: Is it possible for there to ...
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Controlling the reaction of alcohols with acid to either ether synthesis or elimination

Let’s say you take ethanol: $\ce{CH3-CH2-OH}$ and you add an acid and heat. You can get water, the acid, and $\ce{CH2=CH2}$ (a dehydration reaction). However, you can also get $\ce{CH3-CH2-O-CH2-CH3}$,...
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Why does sulfonation of alcohols even work?

I am now near the end of organic chemistry 2, and I'm trying to understand the patterns of reactions so that I can predict them rather than brute force memorizing all of them. Looking at the ...
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Clash between thermodynamic and kinetic processes

I have often come across reactions where kinetic and thermodynamic processes give completely different outputs. I was told that in such cases check temperature, if temperature controlled, then take ...
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Strip away a small amount of aluminium with household chemicals

I'm trying to turn a 6″ diameter mirror (I have spares) into a two-way mirror. It shouldn't be too hard to remove the backing, but then I need to remove most, but not all of the Aluminium plating. My ...
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4k views

How does the solvent determine whether mono- or tribromination of phenol occurs?

In phenol, the $-\ce{OH}$ group activates the benzene ring towards electrophilic substitution. But why is it that the electrophilic bromination of phenol gives trisubstitution (forming 2,4,6-...
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2k views

Relationship between Productivity and Yield

I am trying to formulate an optimization problem. Can you help me understand the definition of productivity and yield? Why is there a trade-off between them during the reaction? Thanks in advance.
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Why is the sneaky method of smothering a grease fire more effective?

In this demonstration, a grease fire is temporarily extinguished if you put the cover on the pan, but reignites as soon as you take the cover off. However, if you slowly slide the cover across the ...
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2k views

How to inhibit Mn2+ autocatalysis in the oxalate-permanganate reaction?

It is well known that permanganate in acidic solution can oxidize oxalate ions (or oxalic acid). The reaction produces $\ce{Mn^2+}$, which catalyzes this very reaction. $$\ce{2MnO4^- + 16H^+ + 5C2O4^...
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Why does the Birch reaction not yield fully saturated products?

Why isn't benzene reduced all the way down to cyclohexane when performing a Birch reaction? (Why is it not reduced further?) Similarly for the reaction with sodium dissolved in liquid ammonia, why ...
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Grignard reaction - exchange of groups

Why is this reaction successful: Why doesn't metal-halide exchange occur easily to get Ar-MgCl and R-Br?
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What makes a compound a dehydrating agent?

When a carboxylic acid with low molecular weight is heated with $\ce{P2O5}$ we get the corresponding anhydride. My book says that this reaction happens with dehydrating agents such as $\ce{P2O5}$. I ...
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What are the differences between diesel and unleaded gasoline?

I am curious about the flammability of diesel fuel and its properties, as I don't deal with it on a regular basis (at all). In particular, I want to know how the fuel works when powering a diesel ...
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1k views

Does pressure affect non-gaseous reactions?

Pressure holds a great significance when it comes to reactions involving gaseous species. Changing pressure can affect the kinetics and even mechanisms of such reactions. However, does pressure hold ...
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Why does addition polymerisation of high density poly(ethene) use low temperature and pressure?

Logically thinking, I thought that it would be high pressure and high temperature that would create high density poly(ethene)... However, that's not the case. Is it because of the catalyst? Why is the ...
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620 views

Does a change in partial pressure for a gas-solid reaction, changes the equilibrium?

This is my reaction, $$\ce{Cd (g) + 1/2 Te2 (g) -> CdTe (s)}.$$ Considering the solid CdTe, $$K = P_{\ce{Cd}}^\mathrm{Eq}\cdot \left(P_{\ce{Te}}^\mathrm{Eq}\right)^{\frac{1}{2}}$$ I only have ...
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Can we do combustion caused by limited supply of air in a lab? How?

For example Ethyne in combustion by limited supply of air $$ \ce{ 2C2H2 + 3O2 ->[\Delta] 2CO2 + 2H2O + 2C } $$ vs. $$ \ce{ 2C2H2 + 5O2 -> 4CO2 + 2H2O + Energy } $$ What are the limits ...
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Relationship between surface area of electrode and reaction rate of hydrogen in fuel cells

I am looking at the effects of increasing the surface area of which the flowing hydrogen fuel is in contact with the anode in a fuel cell. At the anode the hydrogen is catalytically split into ...
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797 views

Free rotation of sigma bonds; diastereomer formation; thermodynamic and kinetic products

For the reaction of 1,3-butadiene with DBr (D = heavy hydrogen), I found that several possible products could be formed. Kinetic products A pair of enantiomers is formed. One of the pi bonds ...
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Other than heating, is there any evidence that normal RF radiation (say, microwave range) can affect chemical reactions?

There's been a lot written (and debunked) about alleged biological effects from RF radiation, even when it's too low powered to cause heating effects or ionization. Is there any chemical reason to ...
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Does anyone know where I can find the reaction rate coefficient and design equation for the electrolysis of brine and sodium hydroxide solution?

equation 1) $\ce{2 Cl^{–} -> Cl_2 + 2e^{-}}$ equation 2) $\ce{2 H2O + 2 e^{–} -> H2 + 2OH^{–}}$ These equations are the key reactions in the chlor-alkali process. I want to model a reactor ...
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3k views

Equilibrium rate constants forward and backwards

Correct me If I am wrong, given a reaction at equilibrium, if we say add more concentration of products to the reaction, the rate going backwards would increase to try to get back to equilibrium. I ...
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774 views

Unfavorable reactions

How can you make an unfavorable reaction go backwards? From my understanding if we wanted a reaction at equilibrium to go backwards (i.e. form reactants from products), we would add more product into ...
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Why does water favour nucleophilic substitution over elimination?

The two broad ways a halogen can leave a haloalkane are nucleophilic substitution and elimination reactions. I was told that elimination reactions (that form a double bond as a $H^+$ is also removed) ...
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Michael reaction or nucleophilic attack at the alpha carbon of an alpha-beta-unsaturated ketone?

What conditions promote a nucleophile to undergo the Michael reaction over the nucleophilic attack at the alpha carbon of the carbonyl group in an alpha-beta-unsaturated ketone? I'm looking for an ...

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