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

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What is the heat of dissolution of sodium acetate trihydate?

Is the reaction endothermic since its crystallization is exothermic?
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Ideal gasses reaction under const temp and pressure

Conceptual problem: let $A + 2B \rightarrow C + 2D$ be a reaction under constant pressure (P) and temp (T), that goes all the way towards the products. A,B,C,D are ideal gases. let $\Delta H$ be the ...
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52 views

Safe yet strong exothermic reaction?

I'm studying chemical engineering at uni (Belgium), and this year (my 2nd) we have to develop and build a stirling engine. It has to be powered by a relatively safe exothermic reaction (not dangerous ...
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25 views

How much heat is released in the combustion of ethylene? [closed]

Given the equation $$\ce{C2H4(g) + 3O2(g) -> 2CO2(g) + 2H2O(l) + 1411 kJ}$$ how much heat is released when $8~\mathrm{g}$ $\ce{O2}$ react?
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Why does the definition of ionisation energy only include gaseous atoms?

I know that in physics there is thermionic emission and the photoelectric effect. These are both method of removing electrons. I think these affects are only for metals due to their de-localized ...
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29 views

Can a reaction with positive Gibbs free energy change ever occur?

If you have an endothermic reaction with a negative entropy change, is it still possible to induce the reaction in some way despite the fact that the Gibbs free energy change is positive or all ...
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1answer
29 views

Entropy - Negligible?

In electrochemistry, the Nernst equation tells us the cell potential for non-standard conditions. I read that the factor $\frac{-RT}{nF}\ln{Q}$ accounts for difference in cell potential due to ...
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43 views

What is Barrier-less reaction in Quantum Chemistry?

After finding a reaction "Transitional State " by GAMESS and finding Hessian Eigenvalues, my project instructor said: " seems your imaginary frequency ( negative eigenvalue ) is not that big ( it is ...
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29 views

The relationship between energy and air pressure?

When boiling water at room temperature, what is the relationship energy has with the air pressure that is making the water boil cold instead of hot?
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50 views

Gibbs free energy or reaction enthalphy

If I conduct a reaction say, $$\ce{CaO(s) + H2O(l) \rightarrow Ca(OH)2 (aq)}$$ let us say , I want to measure the energy generated from the reaction.Will this energy I calculate equal the change in ...
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206 views

Does the “Bat Gen” claim to produce more energy that it uses?

These links claim that inventor Arturo Solis Herrera has created an "everlasting battery". http://www.mexiconewsnetwork.com/news/bat-gen/ http://www.faqs.org/patents/app/20090134007#ixzz10Sh9iLQM ...
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1answer
84 views

What tools can be used to estimate binding energies?

I want to estimate the binding energies of various molecules. What are the analytical and numerical tools I can use for this purpose? In particular I'm interested in bonding energies of dyes to ...
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84 views

Gibbs Free Energy : What is it trying to say actually?

"Gibbs Energy is the useful work that can be extracted from the heat of a rxn or a thermodynamic process." I understand how it predicts the feasibility of a chemical rxn, considering the Entropy ...
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1answer
93 views

How To Get A Double Displacement Reaction Going

So this may be somewhat of a newbie question but here it goes. I was tasked with figuring out how to make some $\ce{NH4ClO4}$(ammonium perchlorate). I found that one way of making it was to react ...
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1answer
40 views

Comparing adamantane carbon types for accepting OH using MM ForceField

I want to compare two type of carbons accepting OH in adamantane which I've shown below. I know the blue position is preferred. But I wanna prove it with energy optimization and MM Forcefield. I ...
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1answer
52 views

How to calculate a reaction's DeltaH using a MM forcefield calculator software?

I want to calculate $\Delta H$ for hydrogenation of Benzene and producing Cyclohexane using MM+ Force Field Energy. I am using Hyperchem for energy calculation and optimization. I calculated the ...
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2answers
76 views

Which formula is correct for calculating the heat of dissolution?

I want to calculate the energy change when a solute is dissolved in water. I know that I can achieve this by using the equation $q=mc \Delta T$. My question is does the mass ($m$) change with the ...
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1answer
42 views

Why is activation enthalpy found and not just rate of reaction?

What is the benefit of finding activation enthalpy and not rate of reaction?
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35 views

First ionization energy of hydrogen molecule

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

How to solve an Arrhenius equation problem?

A widely used rule-of-thumb for the temperature dependence of a reaction rate is that a ten degree rise in the temperature approximately doubles the rate. This is not generally true, especially when a ...
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1answer
53 views

Why the second ionization energy of helium is greater than the first? [closed]

maybe because the first electron has a lower energy. Why does this happen?
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94 views

What happens when an explosion can't lead to volume increase of the thermodynamic system?

I have been searching for an answer to the question for a while but was not able to find 1. My question is: What if an explosion is not able to exit the container?-... so lets take a pipe bomb for ...
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1answer
68 views

Where does the energy of formation of covalent bonds come from?

Consider two $\ce{H}$ atoms. Since the proton in one attracts the electron in another, they attract each other, and form a covalent bond ($\ce{H}-\ce{H}$). Bond forming requires energy (436 kJ/mol for ...
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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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420 views

Why six C atoms are usually seen in cyclic compounds?

When it gets to Carbon-based molecules, one very possible structure when there are more than six C atoms is the hexagon; though not mostly perfect, it emphasizes that six Carbon atoms tend to bond ...
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1answer
85 views

Is the smallest or largest diameter important for the color of a molecule?

I learned that phenol absorbs longer wavelengths than benzene because the electron cloud is bigger. But what is about Penta-1,2,3,4-tetrien (1) and 2,2,-Dimethylpropane (2)? (1) has the largest ...
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37 views

Can we define a new unit instead of specific heat that is constant with temperature rise?

Specific heat plays an important role in calculating energy and thus, heat, enthalpy and etc. But as I sighted the definition for calorie, I was surprised. A calorie is the amount of heat needed ...
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34 views

Search materials by HOMO, LUMO and work function

I need to search organic semiconductors for organic photovoltaics (OPV) by their HOMO, LUMO, work function at 300K (as I understand, WF cannot be derived from HOMO and LUMO because semiconductor can ...
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1answer
32 views

What type of compound/element might be in these glowing tiles

I saw these tiles and these as well while surfing the net, they obiviously glow when their electrons are exited to a higher state and then de-exite over a long period to give off visible light. My ...
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2answers
29 views

Bond Potential Energy Lowering

"Bonds will form only if the potential energy will be lower when the atoms are bonded than when they are separate." Is this statement true? If so, how do endothermic reactions exist? Can't you add ...
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1answer
14 views

effect on kinetic energy of a body with change in temperature

Why doesn't the energy of a body doubles when temperature in centigrade is doubled? I know that it doubles in case of kelvin scale
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77 views

C-H vs C-C: which is stronger?

I've read that nonpolar bonds are stronger than polar ones. If it is true, why C-H bond entalpy (413) is bigger than C-C (348)? I'm very confused at the moment. Thanks a lot
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1answer
46 views

What conditions can cause a material to exist as a gas?

So my question is, how can something exist a gas. Is it when the pressure exerted by the gas is greater than the atmospheric pressure, then it is a gas? And also how do manometers work, how can you ...
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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 ...
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How to calculate the temperature from heat of neutralisation?

The heat of neutralization of $\ce{HCl~ (aq)}$ by $\ce{NaOH}$ is $\mathrm{-55.9~kJ/mol}$ $\ce{H2O}$ produced. If $\mathrm{50~ml}$ of $\mathrm{1.6~M}$ $\ce{NaOH}$ at 25.15 celsius is added to ...
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1answer
50 views

Transfer of energy

After completing a lab for my chemistry class I am finding it difficult to find the initial temperature of an iron nail after being heated. Procedure of the lab went as follows: heat an iron nail, ...
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45 views

“Orthogonality” of chemical elements

Chemical elements are said to be immutable at normal energies, but not at the energies that are orders of magnitude higher. Given that nucleus at normal energies gives us the Periodic Table and at ...
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2answers
59 views

Electron affinity

Concerning the liberation of energy when an atom that is close to the configuration of a noble gas: Where does the energy dissipated from an atom upon receiving an electron come from?
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1answer
36 views

Greatest Energy Output Reaction to Atmosphere Air

First of all i'm no chemist, this is not homework and if you need further clarification please ask. I'll be happy to provide! Imagine that you: have 1 kg of any given chemical X A car battery A ...
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1answer
121 views

Finding Root-Mean-Square of Ne using kinetic energy?

I am not being able to solve the following question: -Find the root-mean-square speed of $\ce{Ne}$ atoms at the temperature at which their kinetic energy is $\mathrm{6.24\ kJ/mol}$. I tried ...
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64 views

Energy Calculations using VIt

The answer for Energy in kJ = $2.5 \times 3600 \times 1 = 9000 kJ$ I do not understand what formula they are using... are they using $VIt$, where $V =12$, $t= 12.5 \times 60 \times 60$ seconds and ...
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1answer
64 views

Explicit differential equation based model of protein folding

I am an applied mathematician interested in the dynamics of potential systems - i.e., systems with multiple unique energy minima. One of the best examples of such systems are protein folding ...
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312 views

Is the transformation of pi bonds to sigma bonds always energetically favorable?

Is the move from pi bonds to sigma bonds always favorable? My professor claims so, except in the case of conjugated pi bonds. I can see how pi bonds going to sigma bonds might be favorable; I know ...
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174 views

ATP break down and energy release?

I have a very basic question. Energy is absorbed to break bonds. Bond-breaking is an endothermic process. Energy is released when new bonds form. Bond-making is an exothermic process. But ATP breaks ...
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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 ...
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57 views

Is S7H4 a chemical?

I want to find a chemical that will react with $\ce{SO2}$ to make water and pure sulfur to battle both greenhouse gasses and drought. I think $\ce{S7H4}$ would do it, but I don't know if it exists. ...
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0answers
311 views

Activation Energy of a rotting apple [closed]

A slightly bruised apple will rot extensively in about 3.5 days at room temperature (22.0 degrees Celsius). If it is kept in the refrigerator at 0.5 degrees Celsius, the same extent of rotting takes ...
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What really happens atomically in an explosion?

Let's say a room is filled with butane, I then throw a cigarette into the room. What happens to the atoms/molecules of the butane when they are in contact with the heat from the cigarette?
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How can I work out what reaction will happen?

I have recently started learning chemistry, and I've been reading a GCSE (UK high school level) textbook on the stuff :D Much of it has been fairly straightforward, though there has been a ...
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1answer
139 views

Why is ΔE described as Q-W and Q+W in different contexts?

Depending on the textbooks looked at, the energy change is described as either Q+W or the signage is changed to Q-W. Which is correct? Is it solely context dependent? Could anyone explain the ...