Questions tagged [energy]

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

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What is the correct definition of the Gibbs free energy of activation?

Is the following correct? Gibbs free energy of activation is used in energy profiles where the stabilities of the species are expressed as changes in Gibbs energy, while the activation energy Ea is ...
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2answers
2k views

Nitrogen dioxide dimerization

$\ce{NO}$ can't dimerize and that is explained because the free electron is in an antibonding orbital. The same is true for $\ce{NO2}$, but it can dimerize, how?
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1answer
7k views

Nitric Oxide Dimerization

This is the molecular orbital diagram for nitric oxide: Now, we know that nitric oxide can dimerize. However, why does nitric oxide dimerize as to form an $\ce{N-N}$ bond? Why not an $\ce{O-O}$ bond? ...
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1answer
179 views

Calorimetry | Heat produced VS Change of enthalpy

There are two questions on the same test paper. Calculate the amount of heat energy, $q$, produced in the reaction Find the change of heat ($-q$). I'm not sure whether or not they mean the same ...
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2answers
1k views

Counting Nodal Planes in cyclopropane

The energy of molecule orbitals increases with more nodal planes. W1 (in the attached picture) has no nodal plane. I'd like to know how to draw the nodal planes in cyclopropane molecule orbitals but ...
3
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1answer
851 views

Volume of gas needed to heat air in room

How much methane gas ($\text{cm}^3$) is required heat $150~\text{m}^3$ of air by $10~^\circ\text{C}$? Please help! I thought this wouldn't be too difficult but I've been stuck for at least an hour ...
5
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1answer
128 views

Does minimizing ANY type of energy ALWAYS predict a state of equilibrium?

My intuition says no, but I am having trouble coming up with concrete examples. I know that minimizing Gibbs free energy predicts a state of equilibrium, while minimizing kinetic or internal energy ...
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1answer
6k views

How much heat is gained/released based off of equation?

Using this equation, $\ce{CaCl2(s) -> Ca^{2+}(aq) + 2Cl^{-}(aq)}$ and $\Delta H = - 325.0 \; kJ $ If you have 15.0 grams of the solid, how much heat is released or gained in kilojoules?
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1answer
996 views

What is the energy change of ethene reacting with hydrogen gas?

$\ce{CH2CH2(g) + H2(g) -> CH3CH3(g)}$ Using this table, source: http://www.kentchemistry.com/images/links/Kinetics/TB08_003.GIF ...
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1answer
105 views

What exactly happens to mass during deuterium fusion?

I know that the mass of Helium-4 is slightly less than the mass of 2x Deuterium it may be made of and that it is the reason fusion gives a lot of energy. But where exactly is this missing mass taken ...
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1answer
490 views

Is there a relation between the ionization energy and the electron affinity?

I am aware of the definition and equation of IE and EA. I was wondering if there is a direct relation between this two quantities with the energy of the neutral specie.
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1answer
201 views

Calculating laser wavelength/power to cause emission of light in a gas?

It's been a long, long time since I've had to worry about electron excitation levels and band gaps. Please forgive (and correct!) my terminology and misconceptions. I've become interested in ...
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1answer
119 views

Could this be a feasible fuel system?

First off, please forgive me, I am a chemistry novice! Overall Process Fuel for the system is distilled water Split water into Hydrogen and Oxygen (electrolysis or similar process) Exhaust Oxygen ...
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1answer
2k views

Why is ionization energy measured in gaseous phase?

When I looked up the definition of ionization energy, it says:- it is the energy required to remove one electron from the shell to infinity in an atom in gaseous state. Why is it measured in ...
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1answer
128 views

Where do the electrons not in the S1 orbital get this “extra energy” from?

In this video, Sal Khan says that an electron reaches a higher energy state if the electron possesses more energy. So I assume that, say in the case of carbon, the electrons not in the S1 orbital have ...
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2answers
148 views

Can a battery powered by iron and air really provide a feasible power source for automobiles?

I'm referring to the Shuttle Battery recently announced (read more on it here) that suggests that: The energy density of the device is up to 7,700 Wh/L. It is more than 5 times higher than state-...
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1answer
8k views

Is it customary to express heat loss as a negative number?

In my chemistry class, we had a problem akin to the following: If an object with mass bla and specific heat bla is placed into a bla g calorimeter with an initial temperature of bla and a specific ...
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1answer
273 views

Storing kinetic energy in bonds

Let's assume a setup with a static linear molecule with three identical atoms connected by bonds and a single atom, identical to the other three, being shot at the molecule. Let's also assume that ...
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0answers
187 views

bond energy calories

I am attempting to optimize interactions for a series of random and test molecules to a protein using docking software. The software uses QM/MMGBSA to calculate free energy in joules (yes it is not a ...
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3answers
4k views

Can natural gas appliances run on Hydrogen?

Can natural gas appliances run on Hydrogen? If so, does the appliance have to be modified and how significant of a modification would it need? Thanks
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1answer
2k views

What does reaction exothermicity say about the stability of molecules

If a reaction is exothermic it means that the energy state of the products is lower than that of the reactants so this will be the state that 'nature' will naturally strive for. Often you see that ...
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2answers
177 views

Lewis model and modern physics

Electron affinity of chlorine = -349 kJ per mole. And, first ionization energy of sodium = 496 kJ per mole while energy required for combining= 147 kJ per mole. Isn't it a contradiction against ...
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1answer
940 views

What is the nature of chemical energy? [closed]

Is chemical energy basically stored energy? I'm not sure how to define "chemical energy" while I know many physical formulas for energy e.g. potential, movement and other. Is chemical energy an ...
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2answers
4k views

Why are there quantised energy levels in the vibrational energy of a molecule?

Why are the energy levels for vibrational energy in a molecule discrete as opposed to continuous? I don't understand how a vibration can't have continuous amounts of energy that depend on the ...
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1answer
570 views

Algebra of conserved quantities for chemical reactions

So there is the standard formation enthalpy $\Delta H^0_f$ and there is also formation entropy. Are there more (independent) quantities? What about the heat capacity? Is there a general theoretical ...

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