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Enthalpy of formation and reaction equations
I'm disagreeing with my chemistry teacher over this enthalpy of formation problem, so can someone tell me if I am right or why I am wrong?
The enthalpy of formation of gaseous sulfur trioxide is $-396~\mathrm{kJ/mol}$. What is the enthalpy of the…
2mia
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Beer freezing after being opened
I am watching the Stoke vs Swansea game, & to be honest, it's pretty boring. So much so, that I've started to wonder why it is that my beer has turned into a slushy after being taken out of the freezer.
I bought it this morning, it wasn't very…
Dan
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Do non-redox reactions exist?
Redox reaction is a type of chemical reaction, and is the result of electron transfer between chemical species. But, all chemical reactions somehow involve electron transfer!
So, are there chemical reactions without electron transfer?
jimyy
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Has anyone sysnthesized perfluorocubane (AKA octafluorocubane)?
Up until now, there have been attempts at synthesizing octafluorocubane, shown below, but success has been elusive.
Has there been any success, and how might the symmetry and fluorine's electron affinity affect its properties?
DrMoishe Pippik
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16
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Metal Compounds that bond covalently
I would like to ask if anyone has a list or knows which covalent compounds have metals in them. For example, beryllium and aluminium are both metals but they bond covalently with chlorine to form beryllium chloride and aluminium chloride…
snivysteel
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Why is a temporary name given to an element with an atomic number above 100?
All the elements with an atomic number more than 100 are given temporary names by IUPAC according to nomenclature rules. For example, element 101 was temporarily named "Unnilunium" until they give it a permanent name (101 is now known as…
Freddy
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16
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4 answers
During phase change in matter, why doesn't the temperature change?
I was working on something in school and came across the question:
Why does the temperature not change much during a phase change?
I'm really not sure why this happens in matter and I couldn't find an answer in my school resources. Does anyone…
GDP2
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Why is there sulfur in black powder / gun powder?
Black powder is composed of charcoal, sulfur and a nitrate salt. The charcoal and sulfur serve as fuel and the nitrate is the oxidizing agent.
However, wouldn't it be cheaper to leave out the sulfur, thus having only charcoal as fuel?
Wikipedia says…
tschoppi
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16
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Why were quasicrystals initially so controversial?
I am a mathematician. My (limited) understanding is that quasicrystals are structured as parts of aperiodic tilings of $\mathbb{R}^3$. Such tilings were already known when Shechtman first studied his alloy. So, I was wondering why there were so many…
George Kontogeorgiou
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What are these crystals on my champagne cork?
I opened up a bottle of champagne that was left in a wine cooler for approx. 8 years. To my astonishment there were small crystals at the underside of the cork.
The crystals are colorless, odorless and have no specific taste at all. What is going on…
tschoppi
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16
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1 answer
Why do green bell peppers become bitter when cooked?
Why do green bell peppers taste sweet raw, but become bitter when cooked (steamed)?
What chemical process is responsible for this? I don't believe the temperatures are high enough for the Maillard reaction
MWB
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16
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4 answers
Is Fluorine more toxic than Chlorine?
Fluorine is more reactive than Chlorine. But does it mean that Fluorine can cause more damage to living tissues? If so, why wasn't Fluorine used in WW1 instead of Chlorine?
My Name
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16
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Are there any full worked examples of DFT calculations?
I just started learning DFT and now I am totally confused.
Assuming I want to use B3LYP:
\begin{align}
v_s\left(\textbf{r}\right) &= v_\text{ext}\left(\textbf{r}\right) + \int d^3r\frac{n\left( \textbf{r}\right) }{\left|\textbf{r} -…
Aug
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Why do electrons jump back after absorbing energy and moving to a higher energy level?
Electrons in a shell absorb energy and move to higher energy levels, but they release their energy and jump back to the shell they originally were in. Why do they jump back? Why can they not keep revolving around the nucleus?
user103186
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Why doesn't NASA or SpaceX use ozone as an oxidizer for rocket fuels?
Presumably, it would be expensive to use ozone ($\ce{O3}$) as an oxidizer instead of $\ce{O2}$, but would the extra oomph be worth it? Does $\ce{O2}$ provide as much thrust/energy/heat as can be provided, given the liquid hydrogen propellant?
I…
Kurt Hikes
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