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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30 views

Are there any pathways that can change a solution to all colors of the rainbow?

The challenge's like this. Suppose you have a beaker containing a liquid of transparent or any color. You add some drops of another liquid and the beaker turns into, say, red after some swishing. You ...
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15 views

How do I measure concentration of CO2 evolved from a decomposition reaction of a metal carbonate?

Context: I have to design and perform an experiment in school where I have to decompose various metal carbonates and measure the rate of reaction. I realise one way to do it is to measure the ...
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What is meant by "analogous reactions" in the Bell-Evans Polanyi Principle?

The BEP principle says that for analogous reactions, enthalpy change and activation energy are linearly related. What is meant by analogous reactions? Eg. For electrophilic addition of HBr to pent-1-...
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42 views

What determines the coefficient B in the Bell-Evans-Polyani equation?

From the Bell Evans Polanyi principle, $E_a = A + B \Delta H$. How is the $B$ coefficient determined? This is my thinking: For exothermic reactions (where the transition state resembles reactants more ...
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41 views

Parameters of NaHCO3 + citric acid + H2O + NaCl mixture potentially impacting functional efficacy in pest control application?

I have been searching for infomation on this application, but have some specific questions that I have not seen directly addressed in the Google/Stack Exchange posts I've come across thus far; below ...
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268 views

Formation of Aniline from Chlorobenzene

My textbook says: When chlorobenzene is treated with aqueous ammonia at 473K under a pressure of 60 atmospheres in presence of cuprous oxide or cuprous chloride, aniline is formed. Notice the ...
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85 views

Temperature control and side reactions in PPAA (T3P) couplings

In a lot of procedures for amide couplings (acid + amine) using PPAA, the coupling agent is added to a cooled solution of the acid, amine, and a non-nucleophilic base such as DIPEA. This is done even ...
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1answer
175 views

Succinic anhydride esterification won't go forward

I'm trying to react succinic anhydride with a decyl alcohol to produce mono-decyl succinate. Literature and Google searches suggest that the monoesterification should proceed without catalyst. However ...
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CSTR reaction cooling jacket - Transfer Functions

I have a CSTR where an irreversible exothermic liquid reaction takes place. Coolant is flowing in the jacket of the tank to regulate the temperature of the fluid in the reactor and control in this way ...
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38 views

What are some convenient examples of so-called dissolved organic matter (DOM) for lab work?

Background, I have come across a chemical reaction system, occurring in nature, that apparently involves the presence of dissolved organic matter (in a catalytic role). My research returns, for ...
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50 views

Why use Stork enamine alkylation?

I recently learned about the Stork enamine alkylation method of adding electrophiles to the beta carboxyl position on a molecule. But I can't seem to find out why a direct synthesis is not possible (...
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1answer
73 views

Good Hess's Law experiment [closed]

I am doing an Internal Assessment for my IB chemistry class, and I want to do something on Hess's Law, and I'll be doing it simulation based, using this website. With the solutions and equipment on ...
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1k 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
45 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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1answer
68 views

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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224 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
720 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
46 views

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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299 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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1answer
18 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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2answers
52 views

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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1answer
118 views

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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140 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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1answer
81 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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3k 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
320 views

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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1answer
494 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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1answer
531 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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2answers
152 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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69 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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39 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
53 views

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
31 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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925 views

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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2answers
81 views

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
274 views

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
235 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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183 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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1answer
32 views

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
327 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
766 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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43 views

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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1answer
43 views

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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262 views

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
903 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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2answers
931 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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1answer
196 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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69 views

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 ${\rm NaCl\to Na+Cl}$ ...