Questions tagged [energy]

For questions relating to the energy required for or produced by reactions, including questions of endothermicity/exothermicity, bond enthalpy, etc.

117 questions with no upvoted or accepted answers
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Does liquids that emit light when vibrated exist?

I am looking for a liquid that illuminates when vibrations are added. It does not have to be strictly chemical, it might as well be something else as well. Maybe a crystal in powder form mixed with ...
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82 views

Solving the Schrödinger equation for a rotating triatomic linear molecule

This source is showing that solving the Schrödinger equation for a triatmoic linear molecule yields the same formula for the rotationaI quantum states $BJ(J+1)$ as for dipoles. For dipoles, the total ...
6
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531 views

How big is the gauche interaction of methyl with phenyl in a disubstituted cyclohexane?

I'd like to compare the equatorial 1-methyl-2-phenylcyclohexane conformation of with axial conformation of 1-chloro-3-methylcyclohexane conformation. In which molecule there is less steric repulsion? ...
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116 views

Catalyzation in Carbonic Acid

I understand the basics of carbonic acid + 1 kcal breaking down into water and carbon dioxide. However, my professor wants me to draw an energy map showing the catalyst in human blood reducing the ...
4
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29 views

Covering conformers in a molecular modelling; consider them as a static entity or work with modelling shifts as well?

I am currently working with a molecular docking project, examining potential affinities of a solvent on a protein in an assay to evaluate potential error margin. The solvent is cyclohexanol (referred ...
4
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224 views

Difference between change in energy level and hyperfine energy level?

The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom. --> This ...
4
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0answers
2k views

Which chemical reaction has the highest specific energy?

Which set of chemicals, reacting together, produces the highest amount of energy, per unit of mass of the substrates? Let's limit the substrates to reasonably stable chemicals (nothing like ...
3
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0answers
26 views

What is the power density of graphite user the Wigner effect?

The energy that graphite released upon a cascade of defects by neutron radiation is 2.7 MJ/Kg, however there is no data on how quick this energy is released. I am interested in this as this not ...
3
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0answers
53 views

CCSD and CISD size consistency problem

I have performed a Gaussian16 calculation to explore the size-consistency problem for the CISD and CCSD methods. The system I am studying is the water dimer and the results are not what I expected at ...
3
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28 views

Can someone help me understand the motivation behind and visualize the dihedral potential and the Urey-Bradley potential?

I am studying statistical mechanics and force-fields, and I see a lot of this formula being thrown around with no explanation: $$U_{\mathrm{dihedral}} = \begin{cases} k(1+\cos (n\psi + \phi)),&...
3
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0answers
137 views

Why does the C−H bond dissociation energy vary in a homologous series of primary alcohols?

Specifically, for the primary carbon atom in the alcohol. Here is bond dissociation energy (BDE) data from chapter three of Luo's Comprehensive handbook of chemical bond energies [1] (boldface refers ...
3
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0answers
93 views

Is it possible to have a negative overall activation energy for a whole reaction mechanism?

I am trying to find out correlation for ignition delay for alkane fuels. The activation energy part of the correlation gives me a negative value. For the ignition delay formulation, is it possible to ...
3
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0answers
81 views

What is the largest known zero-point energy for a molecule?

I was surprised to find out that the zero-point energy (ZPE) for the ground state of $\ce{BH3}$ is a few thousand $\pu{cm-1}$, because for molecules I usually work with, it's much smaller. Does anyone ...
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363 views

Does the activation energy depend upon the stoichiometric coefficient?

For the decomposition of $\ce{N2O5(g)}$ it is given that $$ \begin{align} \ce{2 N2O5(g) &→ 4 NO2(g) + O2(g)} &\quad\text{activation energy} &= E_\mathrm{a}\\ \ce{N2O5(g) &→ 2 NO2(...
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122 views

Which term for heat energy in calorimetry is correct in scientific usage?

In calorimetry several terms are interchangeable: Lower Calorific Value Lower Heating Value Net Calorific Value Net Heating Value The following terms also appear to have identical meanings: Higher ...
3
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0answers
673 views

When is a reaction feasible at room temperature?

Gibbs free energy determines whether a reaction will occur spontaneously or not. Still, the activation barrier of a reaction determines if a reaction will occur at a given temperature. At any non-zero ...
3
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183 views

energy efficiency, transformation from chemical to thermal energy, for district heating plants

If I have a system in which I introduce $\mathrm{100~e.u.F}$ (energy units) derived from chemical energy (i.e. fuel) and generate thermal energy to heat water what are e.u. absorbed by water? I.e. the ...
2
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0answers
76 views

A thermodynamics problem with an interesting equilibrium condition

Usually, when we analyze reactions, we assume that the reaction takes place at constant pressure or at constant volume. But there is no reason to assume this is generally the case, and so my friend ...
2
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0answers
348 views

eV and redox potential

I am trying to estimate the redox potential of an excited state as described in this reference. The paper says: The reduction potentials associated with the excited states cannot be directly ...
2
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49 views

what is the bonding energy of I2 and I3-?

I need some information of bonding energy. I found that the bonding energy of $\ce{I2}$ is $\pu{151 kJ/mol}$ (https://www.chegg.com/homework-help/dimethyl-ether-ch3och3-ethanol-ch3ch2oh-constitutional-...
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0answers
198 views

What is total enthalpy?

I've seen that it's defined as $h_0 = h + \frac{v^2}{2}$, where $h_0$ is the total enthalpy per unit mass. I can see that the $\frac{v^2}{2}$ term probably has something to do with kinetic energy, but ...
2
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0answers
142 views

What is the activation energy barrier of uncatalyzed nitrogen fixation?

I'm interested in the activation energy ($E_\mathrm a$) of uncatalyzed aqueous nitrogen fixation: $$\ce{3 H2 + N2 -> 2 NH3}$$ Biology performs this reaction with the nitrogenase enzyme at room ...
2
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0answers
76 views

Calculating the number of energy states in a particular momentum direction

Given is a 2D scenario of a particle within a container: The circumference shows all the possible 2D spatial directions for a given momentum value of the particle. One of those momentum directions is ...
2
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2answers
4k views

Carbonyl bond vs alkene bond

Why is that carbonyl bonds are stronger than those of alkenes? It's a basic question but I've never really thought much about it. I've read several times that carbonyl bonds are shorter and you need ...
2
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0answers
161 views

Change in enthalpy and entropy for the formation of nickel tetracarbonyl

I was working on an enthalpy/entropy problem and I had a question on predicting the signs of some reactions. For the reaction $$\ce{Ni (s) + 4 CO (g) -> Ni(CO)4 (g)}$$ my textbooks says that ...
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0answers
51 views

Calculate activation energy of intermolecular displacement on a nano particle

I'm simulating a nano particle and wish to calculate the activation energy of the reaction where an atom is displaced from one point on the lattice to a neighboring void( might be at higher energy ...
2
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0answers
151 views

Why do compounds form if overall energy of free ion increases according to CFT

According to crystal field theory, a free ion has certain energy and its energy increases when it is symmetrically surrounded by ligands. Now the degenerate d orbitals split into two new set of ...
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0answers
21 views

Comparison of ways to provide energy to a reaction

As we all know, you can provide energy to a reaction to overcome the activation energy of a reaction by heating the reaction. I have, however, recently sat through a talk where someone 'powered' a ...
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0answers
153 views

Properties of metallic hydrogen

Given the possibility that metallic hydrogen may have recently been produced, and the massive media bloviation that followed, I am curious about some of the "properties" that I heard from multiple ...
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387 views

Why is polyacetylene an insulator?

Recently I have studied Huckel-theory and I appreciated how this approach is suitable to provide simple models to understand chemical behaviour. However, it is highly approximate and qualitative at ...
2
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0answers
60 views

How much energy can be produced by burning sewage gas?

I am an eighth grader. I need to make a science project on the production of electricity from sewage. I know that almost sixty percent of sewage gas is Methane and most of the other constituents are ...
2
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0answers
63 views

Is it possible to observe ATP energy transport in table experiment?

Is it possible to take AMP or ADP, then phosphorylate it convert to ATP to charge with energy, then transport to other place an then observe energy freeing? In table / home / school experiment?
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0answers
356 views

How to calculate minimum temperature of a reaction?

For burning ethanol (its reaction with oxygen), we need a minimum activation energy (a minimum temperature) to start the reaction. Is it possible to calculate what are the minimum temperatures ...
2
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0answers
531 views

Using electron affinity to calculate lattice energy

I am trying to calculate the lattice energy of $\ce{CaBr2}$, I am uncertain of how to incorporate the electron affinity value provided for $\ce{Br2}$ into my calculation. Since electron affinity is ...
2
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0answers
979 views

How to prove that the forward and reverse reactions have the same rate at equilibrium?

I was trying to answer a question from Zumdahl and Zumdahl's Chemistry textbook which asks me to show that the rate constant K is related to the forward and reverse reaction constants: $$K=\frac{K_\...
2
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0answers
616 views

Calculating the wavelength of an emitted photon of a Ne^9+ ion

I'm supposed to calculate the wavelength of an emitted photon going from the 6p orbital to the 2s orbital. The first part of this problem will be to use the equation $$E=-{Rh\over n^2}$$ in order ...
2
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0answers
80 views

Understanding the energy produced from oxidizing 1 kg of lithium

I am reading the following paper in preperation for a research project on the theoretical energy density of batteries: Lithium - Air Battery: Promise and Challenges and on the second page they ...
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0answers
36 views

Should I consider the quantity of each atom when estimating the relative lattice energies of two compounds?

In this video, at 1:30, the presenter remarks that the charge of $\mathrm{Na}$ is $1^{+}$ and that the charge of $\mathrm{Cl}$ is $1^{-}$. Then, at 2:00, he remarks that the charge of $\mathrm{Fe}$ is ...
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119 views

In entropy change of surroundings, what is T?

This question is simpler than the previous one about intuition of entropy; I just need to know whether the $T$ term in $dS_{Surr} = \frac{-dH}{T}$ refers to the temperature of the surroundings or the ...
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0answers
58 views

Is Polymorphism accompanied with an energy change?

Differential Scanning Colorimetry (DSC) is a technique used to identify Polymorphism by revealing two melting points of a pure crystalline structure. DSC shows a peak associated with the formation ...
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271 views

First ionization energy of hydrogen molecule

If we have the dissociation's energies of hydrogen molecule $\ce{H_{2}}$($D_{0}$) and the corresponding molecule ion $\ce{H_{2}^{+}}$ ($D_{1}$) together with the first energy of ionization of hydrogen ...
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101 views

How is N to C ratio measured in forming austenitic stainless steel?

Nitrogen is the future hope of stainless steel industry; since in the production of austenitic steel it can even completely replace Nickel (which is relatively very expensive) in some cases and for ...
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0answers
292 views

How to derive the energy of solvation equation?

The work done as a ion is solvated is given by: $-z^2e^2/8\pi\epsilon r$ but since the top line can be written $Q^2$, for simplicity I will say the equation is $-Q^2/8\pi\epsilon r$. Is this derived ...
2
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0answers
372 views

Delta G values for Pyruvate--> Alanine vs. Oxaloacetate -> Aspartate ->Asparagine

What are the delta G values for the mammalian (human) biosynthesis of alanine from pyruvate, and for the conversion of oxaloacetate to asparagine? (assuming no particular cellular restriction or other ...
2
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1answer
79 views

Why doesn't an sp3s hybridisation exist?

Trying to prove that nitrogen doesn't split its lone pair to form 5 bonds, I thought of a situation that I couldn't rule out; the paired electron being excited to the 3s orbital, so that five bonds ...
2
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1answer
2k views

Why does aluminum chloride have a higher lattice energy than aluminum fluoride?

From the table below (source: McMurry's Chemistry [1, p. 212]), it is evident that $\ce{AlCl_3}$ has a higher lattice energy than $\ce{AlF3},$ even though $\ce{F}$ is smaller than $\ce{Cl}$. Why is ...
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48 views

Cooling down from −78 °C to −88 °C without cryogenics

Say I have a gas cylinder with nitrous oxide and cool it down to −78 °C with dry ice. Is there an endothermic process/reaction that would extract the remaining heat from $\ce{N2O}$ and bring it down ...
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0answers
47 views

Does the anti-rust properties of bluing carbon steel disappear at a certain temperature?

Yesterday I blued my new carbon steel wok over a very high (200K BTU) burner which is capable of getting the wok to 1000+ degrees with ease. I understand that bluing adds a rust-resistant layer which ...
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0answers
39 views

Maximum number of Spectral Lines “A better quantum model shows that there will be n^2 transitions”?

I was parsing the following post What is the maximum number of emission lines when the excited electron of a H atom in n = 6 drops to ground state? and came across with the reply from @porphyrin. cite ...
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27 views

How can I convert cathodic energy efficiency to overall energy efficiency?

Im working on calculation which involve the energy efficiency of producing formate by CO2 electroreduction. I wonder how to convert the reported cathodic energy efficiency (71%) of papers e.g (1) this ...