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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51 views

Real life examples of chemical reactions [closed]

For my upcoming lab report, I want to look at exactly how a simple variable, such as heat or surface area, affects a reaction. But I'm having trouble finding a reaction to test this on, as my results ...
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1answer
28 views

Chemical reaction of radicals with different multiplicity

I am studying the chemical reaction of radicals by computational chemistry software. I just want to know what is the rules for multiplicity. I have two radicals for which, the ground state of one is a ...
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What is the opposite of a catalyst and examples? [duplicate]

I remember a while ago I heard of something that slowed reactions and was effectively the opposite of a catalyst. What is this called? Also would appreciate examples and an explanation of their uses ...
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32 views

What does spontaneous mean in term of forward and reverse reactions?

I just learnt about Gibb's Free Energy and was thinking about an exothermic reaction with a negative change in entropy. This means that the reaction would occur at low temperatures. But that means ...
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1answer
75 views

Reaction Of Carbonic Acid With NaCl [duplicate]

I was just wondering if it was possible for anyone to specify what reaction conditions are required for the reaction between $\ce{H2CO3}$ (Carbonic Acid) and $\ce{NaCl}$ (Sodium chloride)? Does this ...
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2answers
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How can I have iron powder without a fast reaction with oxygen? [closed]

I've seen this video in which fine iron powder reacts immediately with oxygen when exposed to the air, turning into rust. Now, will this reaction always occur with iron powder? Or is there something ...
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1answer
56 views

Formation of Acetal from Hemiacetal?

In the reaction mechanism of formation of Acetal from Hemiacetal, why doesn't H+ attack the Oxygen of OR Group instead of the OH? Since O in OR group has +I effect from two alkyl groups, shouldn't it ...
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16 views

How to measure the speed in a catalized reaction? [closed]

What is cheaper? Set up a constant time of reaction and measure the concentration of the products or; Set up a constant quantity of reactants and, with an indicator, measure the time until the ...
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Why does Sodium Bicarb. Reduce Combustion Rate? [closed]

In many common solid-propellant model rocket engines, Sodium Bicarbonate, $\ce{NaHCO3}$, is used to predictably regulate/limit the rate of combustion of the fuel. My questions are as follows: What is ...
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Decarboxylation of THCA during CO2 Extraction of Cannabis

We have a strange problem. We are performing CO2 extraction on cannabis and we are seeing considerable decarboxylation of THCA to THC. We have high quality temperature sensors at the heat exchangers, ...
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45 views

Is the activation energy always inversely proportional to the reaction rate?

When I obtained the activation energy using the Arrhenius equation for a 10-minute glowstick (rapid, rigorous reaction), it was almost 4 times that of a 12-hour glowstick (slow, mild reaction). ...
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53 views

Are there reactions operated at high temperature at industrial level? [closed]

Temperature is an important parameter when you deal with a chemical reaction, first of all $\Delta G$ and $\Delta G^\circ$ depend on temperature, and as a consequence the spontaneity of a reaction ...
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273 views

How long does it take Freon refrigerant to disappear from a room after an accidental major leakage?

I would like to know please how long does it take Freon refrigerant to completely disappear from a room after an accidental major leakage? Does it stick to surfaces , clothes or walls? Does natural ...
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Controlling rate of endothermic reaction

In an experiment, I have two endothermic reactions taking place simultaneously: $$ \begin{align} \ce{A + B &-> C + D}\tag{1}\\ \ce{E + G &-> Z + F}\tag{2} \end{align} $$ $\ce{C}$ and $\...
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1answer
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Why does phenolphthalein form in this reaction?

This reaction (http://orgsyn.org/demo.aspx?prep=CV1P0476) gives quinizarin as the major product in about 70% yield. However, when the same reaction is conducted with phenol insteas of p-chlorophenol, ...
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34 views

What factors affect the chemiluminesnence of a glow stick reaction?

I know that temperature affects the reaction rate of a glowstick, but are there any other factors? I was thinking the different color dye molecules would have an effect on the reaction rate, since ...
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1answer
110 views

Increasing temperature in system of dynamic equilibrium

According to the article Summary of Le Chatelier's Principle on dynamicscience.com.au, for the process $$\ce{N2(g) + 3 H2(g) <=> 2 NH3(g)}\quad ΔH = \pu{-92 kJ/mol}$$ the forward reaction is ...
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204 views

Do secondary alcohols react faster than primary alcohols or is it the other around? [closed]

My questions is that do secondary alcohols react faster than primary alcohols or is it the other around? This for the oxidation of the alcohol to a ketone or an aldehyde. This reaction is with KMnO4 ...
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75 views

Catalyst that combines oxygen and hydrogen

Are there any known catalysts that can combine hydrogen and oxygen into water? Does this type of reaction have a name? Trying to search for information, it seems to be all about splitting hydrogen ...
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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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38 views

Chloride Process TiO2 recovery

In the chloride process (the process used to create titanium oxide from titanium ore), how is TiO2 collected? What prevents the TiO2 from building up on the walls of the reactor chamber? It's my ...
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1answer
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Is it possible to predict release of acid fumes in certain acid reactions? [closed]

Upon mixing both acids, the reaction between Formic Acid and Sulfuric Acid, besides producing Carbon Monoxide and Water, releases a certain amount of acid fumes. Does anyone know if the fumes, in ...
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What are the chemical principles behind paper/ink deterioration over time and how do I prevent them? [duplicate]

I have been working on a time capsule for the past few months, in which I decided to not include any electronics (ie: no USB). I am done writing the content of the capsule, but I have some concerns ...
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1answer
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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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Role of pH in azo C-coupling reaction, continued

In the question, "What is the role of pH in azo coupling reaction of diazonium with phenol and aniline?" asked by @DhrubaBanerjee and answered by @Klaus-DieterWarzecha, I find several ends ...
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Can equilibrium be calculated at any time of an acid base reaction and still be the same? [closed]

Should the equilibrium constant $K$ be calculated at the end of an acid-base titration or can we calculate it in the middle of the titration for example? If so, will the calculated equilibrium ...
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1answer
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Why do we use Δ to mean heating?

To express heating, we usually use $\Delta$ over reaction arrows like \begin{align} \ce{CaCO3 ->[\Delta] CaO +O2}. \end{align} Why do we use $\Delta$ to mean heating during chemical reactions? I ...
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1answer
157 views

Which reaction rate formula is suited for diatomic molecules in a plasma?

I am an experimental physicist, so I unfortunately do not know much about chemistry except the basics. For my current study, I am investigating diatomic molecule formation in plasma. These diatomic ...
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126 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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What are standard controllers for automatic pH control?

My background in control theory comes from electrical engineering (robots, motors, etc.) and I want to build a control system for automatic pH control. Can I directly apply my knowledge from ...
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1answer
179 views

When is a reaction said to be under kinetic control, is it not easily reversible?

If we consider this reaction: Compound 1 + Compound 2 --> Compound 3 I understand that if a reaction is under kinetic control, the less stable (e.g. a mono-substituted diene) is formed and if the ...
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1answer
509 views

Change of first order rate constant with temperature [closed]

In the decomposition of $\ce{N2O5}$, the time taken to reduce the concentration of $\ce{N2O5}$ half of the original amount is 12 min at $\pu{50^\circ C}$, while 5 h at $\pu{25^\circ C}$ and 10 days at ...
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Why is direct addition not preferred in this reaction? [duplicate]

According to HSAB, direct addition is more preferrable in this reaction with the hard carbonyl carbon electrophile and the hard grignard reagent. But answer given in my book is that with 1,4- addition....
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Which chemicals can counter the corrosion of tamperproof hardware encryption chips?

I'm moving from software implementations to hardware. I need to reverse engineer silicon chips, though the tech that I want to study may have a corrosive chemicals that's supposed to destroy the chip ...
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How to predict and measure excess values of reactivity ratios for copolymerization with three monomers?

I ask this question because I haven't found interesting literature on the subject and I would like to know if my way to think is good or pure bullshit. Also the question is quite long because I have ...
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2answers
723 views

What is the relationship between the constant of equilibrium (Kc) and the position of equilibrium? [duplicate]

I understand that the constant of equilibrium is a ratio of the concentration of the products to the reactants and that this value allows one to estimate whether the position of equilibrium lies to ...
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461 views

Half life of Nitrofurantoin

Both wikipedia and Toxnet list the half-life of Nitrofurantoin as 20-60 minutes in the blood plasma. Can anyone explain how this is so short, especially for an antibiotic, and how it still has time to ...
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184 views

Creating water from hydrogen and oxygen [closed]

Assuming a scientist has two canisters: One with a liter of pure gas of hydrogen (single atoms gas), and one with half a liter of pure gas of oxygen (single atoms gas). The scientist desires to ...
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Is chemical equilibrium possible at any temperature and pressure?

Consider the chemical reaction ${\rm Na+Cl\to NaCl}$ by mixing ${\rm Na}$ with ${\rm Cl}$ (or by mixing ${\rm NaOH}$ with some acid). This process is exothermic while the reverse ${\rm NaCl\to Na+Cl}$ ...
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330 views

How to explain the products of the nucleophilic aromatic substitution of 1-chloro-3-methylbenzene with NaOH?

I guess this reaction is a nucleophilic aromatic substitution where $\ce{ONa-}$ is the nucleophile $\ce{Cl-}$ the leaving group, is that right? Methyl group is a ortho-, para- director. So why should ...
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1answer
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Arrhenius equation in exothermic reactions

According to the Arrhenius equation, the rate of reaction increases when the temperature increases. But according to Le Chatelier's principle, the reaction rate decreases when the temperature ...
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289 views

A chamber to control concentration of a vapor: Is there a name for this equipment?

Mechanical engineer here so please excuse me if my question seems dumb to you! I want to have a chamber $(\approx 40 \times 30 \times \pu{30 cm})$ to control concentration $(\pu{ppm})$ of a flammable ...
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What visual observations can confirm that a reactant is the limiting reagent?

I have this lab question for the lab called Copper Collection Stoichiometry, where we choose an amount of the limiting reagent (iron) for a reaction between copper (II) sulfate and iron. We are to ...
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229 views

Aza-enolates: why no reaction at N

My understanding is that aza-enolates have an advantage over enamines in enolate-type alkylations because the reaction at N is less likely. As a result, unactivated electrophiles can be used (i.e. ...
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Mechanism of Halogenation of Alkene

In the above reaction, we use a non-polar compound (such as CCl$_4$) as a solvent. Then, why does the Br$_2$ polarise on attack by the alkene, even though a non-polar solvent does not encourage ...
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Can carbocation rearrangements have kinetic and thermodynamic products? [closed]

As the figure in this webpage says, at low temperatures, the major product of hydrohalogenation of 1,3-butadiene is the kinetic product, the 1,2-addition product. At high temperatures, the major ...
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526 views

E2 Reactions in Cyclic Structures

In my textbook, the percentages of anti-eliminations are given which are quite contrary to expectations. The reason is also not given quite clearly. Why does the preference for anti-periplanarity ...
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1answer
122 views

Hydride Donating Ability [closed]

We know that some compounds can donate $\ce{H-}$ anion to attain stability. What are the conditions under which it occurs and what should be the extent of stability of the product for this pathway to ...
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Does gravity affect the rate of a chemical reaction?

For example, on planets with lower gravity, would the rate of reactions be lower because the reactants are slower to mix with one another?
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Can the summation of activation energy and reactant's initial internal energy change with temperature?

Look at the graph. The orange arrow represents the summation of activation energy and reactant's initial internal energy. Can it change with temperature? Is there any specific name for this summation?