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It's there in every high-school textbook: $O_2$ is the supporter of combustion. Without $O_2$ combustion cannot take place. Why? And why only $O_2$? Why not some other element?
And, what happens when a combustible gas burns in air? Say $H_2$? |
Why is O2 the supporter of combustion? |
When do covalent bonds of a molecule $M$ extend or compress while no bonds in $M$ are broken? I can conceive of some possibilities but I don't know how common they are:
- Temperature changes
- Inter-molecular forces around $M$ which may stretch or compress $M$ in various directions
- The transition from $M$ int... |
Cl- is a monodentate ligand. It has four lone pairs then why it can't donate two lone pairs to central atom and act as a bidentate ligand? |
Why Cl- can't act as bidentate ligand? |
Because it is the phosphoester of dihydroxyacetone. One of the -OH groups was used in the esterification reaction.
See [Here][1]
[1]: http://guweb2.gonzaga.edu/faculty/cronk/biochem/D-index.cfm?definition=DHAP |
While refreshing myself on denticity to answer another question, I started to read about [hapticity][1], which is the coordination of a ligand through multiple continuous atoms. A famous case is ferrocene (bis[$\eta^5$-cyclopentadienyl]iron, $\ce{Cp2Fe}$), where all five carbon atoms in each cyclopentadienyl ligand (Cp... |
Do eta-4 benzene ligands participate in Diels Alder or other cycloadditions? |
Why we don't get sharp point at equivalence points in case of acid base titration other than the case of strong acid and strong base titration? |
I was wondering what the crystal structures of FCC, BCC and HCP actually look like, and where atoms are placed in their configuration?
Specifically I'm looking at elemental nickel, iron and cobalt in their lowest temperature lattice type. (Below their curie temperature to be exact.) |
Many years ago, I used to work as a gold exploration geologist. One of the main locations was a salt lake in Western Australia detailed in the document [WMC Resources Exploration Successes inN Lake Terrains - Applications of Element Dispersion, Kambalda W.A][1] (Carey and Dusci, 1993).
In the article, and in my res... |
How does the ambient temperature affect the rate of redox reactions in a salt lake? |
I did an experiment where i dissolved 30 grams of zinc sulfate in water and boiled it with strips of solid zinc metal and strips of copper metal and a layer of zinc was deposited on the copper. I know that if you placed solid copper in zinc sulfate aqueous without the solid zinc nothing would happen because zinc is mor... |
why does znso4 aqueous solution when boiled with solid zinc and solid copper cause zinc metal to be deposited on copper? |
If one considers boiling points ($^{o}C$) of primary alcohols, one finds the following:
- methanol: 65
- ethanol: 79
- 1-propanol: 97
- 1-butanol: 117
- 1-pentanol: 138
This trend is due to Wan der Waals forces increasing with molecular weight.
Now if one focuses on melting points, I would expect ... |
First of all what is exactly gibbs fre energy ??? How can we visualise it ?? How does gibbs free energy changes in a chemical reaction ?
Now , isn't potential the amount of work done per unit charge to bring it from infinite to that point ?
Now the ionisation in cell goes through multiple steps ie, eg
Zn(s)-->zn... |
how is the relation between gibbs free energy and cell potential? |
I did an experiment where I dissolved 30 grams of zinc sulfate in water and boiled it with strips of solid zinc metal and strips of copper metal and a layer of zinc was deposited on the copper.
I know that if you place solid copper in zinc sulfate aqueous without the solid zinc nothing would happen because zinc is ... |
How to convert glucose to fructose? Moreover, can there be direct conversion(not necessarily in a single step), or we have to use indirect means, such as from sucrose, or other higher carbohydrates, and then separating fructose from the products? |
![enter image description here][1]
[1]: https://i.stack.imgur.com/Apvfg.gif
> - An ionic bond is the bonding between a non-metal and a metal, that occurs when charged atoms (ions) attract after one loses one or more of its electrons,and gives it to the other molecule, for example sodium and chlorine. This ma... |
Why do ionic compounds dissociate whereas coordinate complex's won't? |
I'm interested in chemical reaction mechanism with more exotic particles. The [Wikipedia page](en.wikipedia.org/wiki/Allotropes_of_oxygen#Atomic_oxygen) seems to imply that the normal atomic oxygen is $O(^3P)$, is that right?
I also came across $O(^1D),O(^1S),O(^5P)$ and some longer strings like $O(3S3s)$. What are... |
What are the known atomic oxygen species? |
First of all what is exactly Gibbs free energy in regards to an electrochemical process? How can we visualise it? How does Gibbs free energy change in an electrochemical reaction? How is it related to the cell potential?
Isn't potential the amount of work done per unit charge to bring it from infinite to that point?... |
how is the relation between Gibbs free energy and cell potential? |
I'm interested in chemical reaction mechanism with more exotic particles. The [Wikipedia page](en.wikipedia.org/wiki/Allotropes_of_oxygen#Atomic_oxygen) seems to imply that the normal atomic oxygen is $O(^3P)$, is that right?
I also came across $O(^1D),O(^1S),O(^5P)$ and some longer strings like $O(3S3s)$. What are... |
I'm interested in chemical reaction mechanism with more exotic particles. The [Wikipedia page](en.wikipedia.org/wiki/Allotropes_of_oxygen#Atomic_oxygen) seems to imply that the normal atomic oxygen is $O(^3P)$, is that right?
I also came across $O(^1D),O(^1S),O(^5P)$ and some longer strings like $O(3S3s)$. What are... |
I'm interested in chemical reaction mechanism with more exotic particles. The [Wikipedia page](http://en.wikipedia.org/wiki/Allotropes_of_oxygen#Atomic_oxygen) seems to imply that the normal atomic oxygen is $O(^3P)$, is that right?
I also came across $O(^1D),O(^1S),O(^5P)$ and some longer strings like $O(3S3s)$. W... |
I am writing an essay on the origin of life and I was reading an article on hydrothermal vents. [(Peptides by Activation of Amino Acids with CO on (Ni,Fe)S Surfaces: Implications for the Origin of Life)][1].
It appears that (Ni,Fe)S has played an important role in protein synthesis, but I wanted to know more about ... |
What is 'coprecipitated (Ni,Fe)S'? |
After searching on Google about [Isomerization of Glucose to Fructose][1], you can find so many sources that explain the process. I think that [this][2] one is easy to understand among them. It explains that
>The isomerization of glucose to fructose is part of the glycolysis cycle that converts glucose to pyruvate. ... |
Also, are there any exceptions that you know of? |
Is Coupling Reactions, Heck Reaction for example, different from Coupled Reactions like the production of Glucose 6-phosphate in living organism? |
First of all, who says coordination complexes don't dissociate? The interesting chemistry happens right there, and without dissociation no catalytic coordination compounds would be possible!
Now, the way I see it, when you move your compound, be it ionic, covalent or coordination, from air to a condensed phase, it w... |
![enter image description here][1]
[1]: https://i.stack.imgur.com/Apvfg.gif
> - An ionic bond is the bonding between a non-metal and a metal, that occurs when charged atoms (ions) attract after one loses one or more of its electrons,and gives it to the other molecule, for example sodium and chlorine. This ma... |
I do know that the lanthanides start with the element lanthanum, but why? Lanthanum doesn't even have an f orbital, so why isn't it considered a transition metal? It's the same way with actinium, which doesn't even have any electrons in its 5f orbital, why isn't it also a transition metal? |
Why is lanthanum a lanthanide and actinium a actinide? |
Why did Thomson assume that electrons are embedded in a positively charged sphere? Why did he not assume that they are positively charged particles embedded in a negatively charged sphere? |
I have understood the [basic mechanism][1] of cannizzaro reaction. But I am unable to understand the products formed in case of a crossed Cannizzaro reaction.
Suppose Benzaldehyde and Formaldehyde are heated in presence of $\ce{NaOH}$ to carry out Cannizzaro transformation. I have read that it is Benzyl Alcohol a... |
One of the questions in my textbook was to arrange the following in order of their reactivity for nucleophilic addition reaction.
1)$\ce{(p-NO2Ph)_2CO}$
2)$\ce{(CH3)_2CO}$
3)$\ce{(p-NO2Ph)COH}$
4)$\ce{CH3COH}$
I know there are two factors in play here. One is the steric factor (4>3>2>1) and annothe... |
In order to create a simple program which calculates titration curves (also to provide some closure in the comments [here][1]) I am trying to come up with all the equations so I can calculate the equilibrium proton concentration for any given concentrations of any two given weak acids/bases.
This is a collection of ... |
How does one calculate the pH of an aqueous solution of a weak acid and a weak base? |
One of the questions in my textbook was to arrange the following in order of their reactivity for nucleophilic addition reaction.
1. $\ce{(p-NO2Ph)_2CO}$
2. $\ce{(CH3)_2CO}$
3. $\ce{(p-NO2Ph)COH}$
4. $\ce{CH3COH}$
I know there are two factors in play here. One is the steric factor (4>3>2>1) and ann... |
I'm trying to understand how to solve this question for my physical chemistry class, but after many attempts, I am still not getting the same solution as the solution manual. If anyone can help me I'd greatly appreciate it.
The question is:
The solubility of mercury (I) iodide is 5.5 fmol/L in water at $25^o C$. ... |
[Have a look at this paper][1]
Summarizing:
- put food coloring to 35% isopropyl alcohol in water.
- add ammonium sulfate
What happens ? Once ammonium sulfate added and the solution mixed, the ammonium sulfate dissolves, pushing the isopropyl alcohol out of the aqueous solution (and the food coloring as we... |
In Clayden et al., [Organic Chemistry][1], p. 322, the authors compare the reaction energy profile for ester formation from a) acyl chloride and b) anhydride:
![Clayden et al., Organic Chemistry, OUP 2001][2]
They then write
> The energy levels of the starting materials, the transition state, and
> the interm... |
In Clayden et al., [Organic Chemistry][1], p. 332, the authors compare the reaction energy profile for ester formation from a) acyl chloride and b) anhydride:
![Clayden et al., Organic Chemistry, OUP 2001][2]
They then write
> The energy levels of the starting materials, the transition state, and
> the interm... |
I'm trying to understand how to solve this question for my physical chemistry class, but after many attempts, I am still not getting the same solution as the solution manual. If anyone can help me I'd greatly appreciate it.
The question is:
The solubility of mercury (I) iodide is 5.5 fmol/L in water at $25^o C$. ... |
You are correct that you need $\Delta G^\circ =-RT\ln{K}$ and that the equilibrium constant in this case is $K_{sp}$ the solubility product constant, which is defined for a process like this one to be:
$$\ce{A_{m} B_{n} (s) <=> mA^{n+}(aq) + nB^{m-}(aq)}$$
$$K_{sp} = \ce{[A^{n+}]^{m} [B^{m-}]^{n}}$$
In your case... |
According to both caffeine's [pubchem page][1] and [chemspider page][2] its boiling point lies at 173°C and its melting point at ~235°C. How can it melt at that temperature if it already sublimated at 173°C? Or is that the temperature of the triple point? If so, how come none of those pages gives any pressure specifica... |
Does a grain of salt have exactly equal amount of sodium and chlorine? I know that the formula unit of salt is 1:1, but for example if there is 10000000 atoms of sodium is it possible that that there is 9999999 atoms chlorine? Thanks. |
Does a grain of salt have exactly equal amount of sodium and chlorine? |
Why has no one ever been able to synthesise cyclopentyne as a stable molecule? I've been thinking about this for quite some time and I can't seem to figure it out. Something to do with angular strain in the molecule? |
Why is cyclopentyne unstable? |
Which bond is stronger, Ionic or covalent? I have a lot of confusion about this. Please tell me clearly. |
Which bond is stronger, ionic or covalent? I have a lot of confusion about this. |
I performed an electrolysis of an aqueous sodium carbonate solution with a platinum electrode and a chromium-vanadium-alloy electrode. The solution turned yellow at the chromium-vanadium-alloy electrode (I suspect that it is sodium metavanadate (NaVO3))
Then I also performed an electrolysis in an aqueous sodium car... |
Imagine some $S_N2$ reaction involving an aliphatic $sp^3$ carbon with a halide leaving group (e.g. Iodide or Bromide). Given the rise of femtosecond (e.g. using a mode-locked Ti:sapphire laser) and even attosecond spectroscopy, I'm curious if there are any studies that have measured the properties and approximate lif... |
What is the approximate lifetime of an $S_N2$ transition state complex? |
Textile Fabrics are made out of cellulose fibres that can be derived from cotton or bamboo. As far as I know all grasses contain cellulose, so why are only a few grasses used? What makes them so special? Why could you not use for example gamba grass/andropogon gayanus for that, which contains 30% cellulose and 21% hem... |
What chemical properties make some grassses usable for producing textile fabrics? |
Is there a scientific basis for the coffee making equipment which Gale describes in Breaking Bad?<p>![Picture of the "Ultimate" coffee maker][1]</p> <p>He talks about maintaining the right conditions for bringing out the coffee flavor without degrading it.</p>
[1]: https://i.stack.imgur.com/RXXSf.jpg |
In this diagram (Evans et al., J. Chem. Edu.) the current is non-zero, but the potential is still below the normal potential. How can the compound become oxidized at the working electrode, when the applied potential is still below the normal potential of the compound?
![enter image description here][1]
[1]: h... |
Why is current non-zero when applied potential is still below E$^0$ in cyclic voltammetry? |
I performed an electrolysis of an aqueous sodium carbonate solution with a platinum electrode and a chromium-vanadium-steel-alloy electrode. The solution turned yellow at the chromium-vanadium-alloy electrode (I suspect that it is sodium metavanadate (NaVO3))
Then I also performed an electrolysis in an aqueous sodi... |
What are the products formed when phenol reacts with monoiodomethane in presence of dilute alkali? Also, a reaction with a mechanism would be helpful. Thanks for any help. |
How does phenol react with monoiodomethane in presence of dilute alkali? |
I don't understand bond enthalpy vs. enthalpy of atomization in relation to temperature.
Example to illustrate my miserable confusion:
The bond enthalpy of an H-H bond is 436 kJ/mol, and the enthalpy of atomization of H is half that (as it refers to moles of H produced, not H2). This I get.
If I were to take... |
H-H bond enthalpy is 436 kJ/mol. To break apart a mole of H2 into H atoms, I need to spend 436 kJ. Whether I take that mole of H2 gas out of the freezer or out of the sauna, it doesn't matter, right?
But this is counter-intuitive. Of course I would have to spend more heat to atomize the H2 mole from the freezer th... |
H-H bond enthalpy is 436 kJ/mol. To break apart a mole of H2 into H atoms, I apparently need to heat it by 436 kJ.
Does this only apply at the standard temperature of 298 kelvin?
What about H2 gas (or liquid) at 0 K?
H2 gas at 500K?
Does the bond enthalpy vary with temperature?
And is it practically jus... |
Say for example, you have isopropyl alcohol. Is there any reason why if you react it with bromine that it won't form a radical, as one of the bromines removes one of the protons adjacent to the hydroxyl group on the alkane, and then propagate into 2-bromo,2-propanol? |
Is there any reason why halogenation of substituted alkanes through free radical substitution? |
Is there such a thing as a dye that can stain both oil and water? In other words, does anyone know of an amphiphilic dye? Maybe a surfactant that is also a pretty shade of blue? Or maybe turn one color in oil, but another in water, but stain both well?
Thanks |
A good approach to this type of problem is to break it down into smaller problems.
We know we have phenol $\ce{PhOH}$, methyl iodide $\ce{CH3I}$, and base, let's say $\ce{NaOH(aq)}$. Instead of trying to figure out what these three things do all together, can we determine what might happen with just two of them?
... |
Is there any reason why halogenation of substituted alkanes doesn't occur through free radical substitution? |
What are some white compounds that look like powder (like flour) and immediately black after being heated? It turns immediately black and creates a odorous gas.
Thanks! |
Question about a compound? |
When water temperature reaches to 100 degrees of Celsius, the atoms get so excited that the hydrogen atoms loose the bonds the oxygen atom and therefore they start to become gas. I get that. But in room temperature (23C) there is no excitation in the atoms? or is there? |
Why does water evaporates in room temperature? |
To add to Jerry's answer, the amount of evaporation of water also depends on pressure.<p>Infact, one way of defining boiling point is the temperature at which the vapour pressure equals atmospheric pressure. So, you can actually [boil water at room temperature][1].</p>
[1]: http://www.youtube.com/watch?v=Ks4VuXTTKmo |
What sort of a <b>microstructure</b> would you get on bubbling Aluminium vapors through a large tank of Helium?<p>Would it be a glassy microstructure and/or would you get nano-powders and/or a new crystal structure formation because of the excess helium which would be present in the aluminium matrix? Ignore metal coola... |
When water temperature reaches $100^\circ C$, the molecules get so excited that the hydrogen atoms lose the bonds the oxygen atom and therefore they start to become gas. I get that, but at room temperature ($23^\circ C$) there is no excitation in the atoms? Or is there? |
Why does water evaporates at room temperature? |
When water temperature reaches $100^\circ C$, the molecules get so excited that the hydrogen atoms lose the bonds to the oxygen atom and therefore the water starts to become gas. I get that, but at room temperature ($23^\circ C$), is there no excitation in the atoms? Or is there? |
Why does water evaporate at room temperature? |
<strike>What sort of a <b>microstructure</b> would you get on bubbling Aluminium vapors through a large tank of Helium?</strike><p>Would it be a glassy microstructure and/or would you get nano-powders? <strike>and/or a new crystal structure formation because of the excess helium which would be present in the aluminium ... |
Rapidly cooling Aluminum vapour to solid state? |
Is there any reason why halogenation of substituted alkanes wouldn't occur through free radical substitution? |
What are the products formed when phenol reacts with monoiodomethane in presence of dilute alkali? Also, a reaction with a mechanism would be helpful. Thanks for any help.
EDIT: Phenol Reacts with NaOH to give a salt, Sodium Phenoxide. And yes, I was thinking about addition of Iodine to the Ring, but I don't know ho... |
Alcohol Reaction Product prediction? |
There have been various explanations posited for the [$\alpha$-effect](http://en.wikipedia.org/wiki/Alpha_effect). It is currently in the [list of unsolved problems in chemistry](http://en.wikipedia.org/wiki/List_of_unsolved_problems_in_chemistry) on Wikipedia, but, due to a lack of references to that effect, I'm not e... |
Is there a general consensus on the causes of the $\alpha$-effect? |
What is the most rare element in periodic table? I have a lot of confusion about this. |
Well, the first question to answer would be: where? The rarest element in the universe? the sun? in meteorites? on earth? in the ocean? in humans? We can tap in to the curated datasets provided by Mathematica to get the answer:
Elements up to atomic n... |
Imagine some $S_N2$ reaction involving an aliphatic $sp^3$ carbon with a halide leaving group (e.g. Iodide or Bromide). Given the rise of femtosecond spectroscopy (e.g. using a mode-locked Ti:sapphire laser) and even attosecond spectroscopy, I'm curious if there are any studies that have measured the properties and ap... |
Well, the first question to answer would be: where? The rarest element in the universe? the sun? in meteorites? on earth? in the ocean? in humans? We can tap in to the curated datasets provided by Mathematica to get the answer:
Elements up to atomic n... |
Will a Galileo's Thermometer containing liquid paraffin explode in my car if the temperature is above 35 degrees Celsius? |
According to CFT, the degenerate d-orbitals split into $eg$ and $t_2 g$ groups. Are these the outermost nd orbitals which are vacant(4-d in case of 4th period) or the penultimate filled (n-1)d orbitals?
If they are the (n-1)d orbitals, how can they be degenerate if they are not completely filled? If they are (vacant... |
Which d-orbitals split according to CFT? |
What is going on in this reaction? |
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