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Can someone please explain the bonding in a bridged metal carbonyl (like diiron nonacarbonyl)?
I cannot understand what kind of bonds (sigma/pi) exist between the bridging carbonyls and the metals.
Also why aren't the metals charged in such a case?
What is the bond order in such a case?
|
A lot of the organometallics are rather... interesting compounds to work with. The most famous (among those who care, anyway) is *tert*-butyllithium or t-BuLi. It is the textbook example of a pyrophoric substance, demonstrated to pretty much every chemistry major as an air-sensitive chemical requiring special handling ... |
In para-aminobenzoic acid, how can I know whether amino group losses or not one proton when pH exceeds 8.5? I have only found two values for pKa but I never found info about pKa (in this case it would be third pKa at pH>8.5) of the amino group.
In any case I guess at basic pH, negative charge over NH2 would be stabi... |
In aminobenzoic acid, do we have three different pKa's? |
When is it okay to use $Q=mc\Delta T$, is the equation only for calorimetry questions? When a question talks about heat how do I know if i'm measuring $\Delta H$ or Q? |
When is it okay to use $Q=mc\Delta T$, is this equation only for calorimetry questions? |
I have this iron pan that got rusty from not being properly dried. Scrubbing it I was able to get rid of most of the rust, but there's still some I just can't remove. I thought I could chemically remove it, but I myself am a bit rusty on the inorganic chemistry subject, so I couldn't think of any way of doing it withou... |
Although [fp](http://chemistry.stackexchange.com/users/1300/f-p)'s answer is absolutely correct and I see that you have something more than high school chemistry, I'd like to give a more elaborated answer, if you or anyone else reading this has any interest the basic principles of ICP-OES. It is a relatively complex pi... |
Although [fp](http://chemistry.stackexchange.com/users/1300/f-p)'s answer is absolutely correct and I see that you have something more than high school chemistry, I'd like to give a more elaborated, yet simplistic answer, if you or anyone else reading this has any interest on the basic principles of an ICP-OES - you on... |
Although [fp](http://chemistry.stackexchange.com/users/1300/f-p)'s answer is absolutely correct and I see that you have something more than high school chemistry, I'd like to give a more elaborated, yet simplistic answer, if you or anyone else reading this has any interest on the basic principles of an ICP-OES - you on... |
I have a decanter which I use fairly often to pour out wines. I typically rinse it with hot water after the last wine has come out, but I cannot prevent it from forming 'residual' wine stains over time.
The last time I wanted to clean it, I looked on the internet for advise on cleaning. There is tones of it ([Stain... |
I have a decanter which I use fairly often to pour out wines. I typically rinse it with hot water after the last wine has come out, but I cannot prevent it from forming 'residual' wine stains over time.
The last time I wanted to clean it, I looked on the internet for advise on cleaning. There is tonnes of it ([Stai... |
The dissociation of formic acid (HCOOH) is:
$$
\ce{HCOOH -> H+ + COOH-}
$$
Why is the charge on COOH -1 though? Is it achieved through:
1*(C4+) + 2(O2-) + 1*(H-)
?
Does carbon exist as a 4+ ion?
Also, as a somewhat unrelated question, can an acid donate multiple H+ ions (or can a base receive multiple H+ i... |
Why is the charge of COOH -1? |
In certain applications some sorts of stainless steel `(V2A, 1.4301)` corrode when exposed to $\small{\ce{Cl^-}}$ in water, or at least it is strongly advised to use other steels.
The conditions that were explained to me as being especially bad were: redox potential >0, acidic environment.
Under these conditions,... |
The dissociation of formic acid ($\ce{HCOOH}$) is:
$$
\ce{HCOOH -> H+ + COOH-}
$$
Why is there a charge on $\ce{COOH^{-1}}$
though? Is it achieved through:
$$1\times(\ce{C{4+}}) + 2\times(\ce{O2-}) + 1\times(\ce{H-})?$$
Does carbon exist as a 4+ ion?
Also, as a somewhat unrelated question, can an acid... |
Why is there a charge on $\ce{COOH^{-1}}$? |
The dissociation of formic acid ($\ce{HCOOH}$) is:
$$
\ce{HCOOH -> H+ + COOH-}
$$
Why is there a charge on $\ce{COOH^{-1}}$
though? Is it achieved through:
$$1\times(\ce{C^{4+}}) + 2\times(\ce{O^{2-}}) + 1\times(\ce{H-})?$$
Does carbon exist as a 4+ ion?
Also, as a somewhat unrelated question, can an ... |
I am conducting a bio-chemistry related experiment and I have been unable to understand a step which is commonly performed.
My aim in this step is to apply a PEG (Polyethylene glycol ) silane layer.
After immersing ITO (Indium Tin Oxide) slides in a PEG-concentration, the slides are incubated for 18 hours at a te... |
Why incubating for 18 hours at 60 degrees Celsius? |
Until you post the original source procedure, my answer is going to be generic.
> When I am repeating an experiment I found in the literature, why do I need to do [insert step that seems unnecessary, difficult, or just plain long]?
The short answer is, **because it works.**
You need to incubate the slides at 6... |
I am conducting a bio-chemistry related experiment and I have been unable to understand a step which is commonly performed.
My aim in this step is to apply a PEG (Polyethylene glycol) silane layer.
After immersing ITO (Indium Tin Oxide) slides in a PEG-concentration, the slides are incubated for 18 hours at a t... |
Why do we need to incubate this system for 18 hours at 60 degrees Celsius? |
I am conducting a [bio-chemistry related experiment][1] and I have been unable to understand a step which is commonly performed. The procedure that is confusing me is outlined in the [supporting information][2], beginning on page S2.
My aim in this step is to apply a PEG (Polyethylene glycol) silane layer.
Afte... |
$$\ce{NaF +H_2SO_4 \rightarrow NaHSO_4 +HF} (1a)$$
$$\ce{NaCl +H_2SO_4 \rightarrow NaHSO_4 +HCl} (1b)$$
$$\ce{NaBr +H_2SO_4 \rightarrow Br_2 +SO_2 + 2H_2O} (2)$$
$$\ce{NaI +H_2SO_4 \rightarrow 4I_2 +H_2S + 4H_2O} (3)$$
**Conventional explanation:** $\ce{NaI}$ is a strong enough reducing agent to reduce the Sulphu... |
The acid in question has pKa about 1.29. Density of 98% w/w solution is d=1.323 g/cm3. I would like to find the number of undissociated acid molecules (XH), water molecules (W), dissociated acid molecules (X-), and hydronium ions (W+).
The molar mass of the acid (XH) is 125.1 g/mol. Thus 98% w/w solution correspond... |
The acid in question has pKa about 1.29. Density of 98% w/w solution is d=1.323 g/cm3. I would like to find the number of undissociated acid molecules (XH), water molecules (W), dissociated acid molecules (X-), and hydronium ions (W+).
The molar mass of the acid (XH) is 125.1 g/mol. Thus 98% w/w solution correspond... |
I am reading a paper ([Shirts, M. R.; and Pitera, J. W. and Swope, W. C. and Pande, V. S. *J. Chem. Phys.* **2003**, *119*, 5740-5761][1]). Near the beginning of the paper (page 5745), the authors state:
> Experimental free energies of hydration for weakly soluble solutes are
> determined from concentration measur... |
How is hydration free energy of a solute measured experimentally? |
$$\ce{NaF +H_2SO_4 \rightarrow NaHSO_4 +HF} (1a)$$
$$\ce{NaCl +H_2SO_4 \rightarrow NaHSO_4 +HCl} (1b)$$
$$\ce{2NaBr +H_2SO_4 + 2H^+ \rightarrow Br_2 +SO_2 + 2H_2O + 2Na^+} (2)$$
$$\ce{8NaI +H_2SO_4 +8H^+ \rightarrow 4I_2 +H_2S + 4H_2O +8Na^+} (3)$$
**Conventional explanation:** $\ce{NaI}$ is a strong enough reduc... |
Sulphur and oxygen belong to the same group. Sulphur has a vacant d-orbital while oxygen has no vacant d-orbital.
What does having "no d-orbital" mean? Orbitals are just the spaces around the atom. How can you say that there is no space around the atom which makes the d-orbital?
And my second question is that wh... |
Sulphur is a diamagnetic element, meaning that it has no unpaired electrons. But its electronic configuration for valence shell is just like oxygen because they are in the same group i.e ns2, np4.
My question is that why is sulphur diamagnetic. If there are 4 electrons in p-orbital of its valence shell then shouldn'... |
Sulphur and oxygen belong to the same group. Sulphur has a vacant d-orbital while oxygen has no vacant d-orbital.
What does having "no d-orbital" mean? Orbitals are just the spaces around the atom. How can you say that there is no space around the atom which makes the d-orbital?
|
Both SF6 and SH6 and SF4 and SH4 have the same central atom and the same hybridisation but my teacher specifically mentioned that SH6 and SH4 son't exist. I've looked everywhere but I can't figure out why? I'd apreciate some insight into the problem. |
Why do compounds like SF6 and SF4 exist but SH6 and SH4 don't? |
Both $\ce{SF6}$ and $\ce{SH6}$ and $\ce{SF4}$ and $\ce{SH4}$ have the same central atom and the same hybridization but my teacher specifically mentioned that $\ce{SH6}$ and $\ce{SH4}$ don't exist. I've looked everywhere but I can't figure out why? I'd appreciate some insight into the problem. |
Why do compounds like $\ce{SF6}$ and $\ce{SF4}$ exist but $\ce{SH6}$ and $\ce{SH4}$ don't? |
Hypervalency is a [bit of a touchy subject][1], since there are strong opposing proponents for both the [hybridization camp][2] and the [3-center-4-electron bond camp][3].
While not directly related to your question's compounds, I shall point you to a fun book by Errol Lewars on the computational analysis of uncommo... |
With reference to the crystal field splitting in octahedral complexes,my textbook shows the following table of distribution of d-orbital electrons in octahedral complexes,based on the energy difference of t2g and eg orbitals:
[Table](https://i.stack.imgur.com/rw6Kh.jpg)
Do ALL the d orbital configurations(ie pert... |
Which d-orbital configurations form an octahedral complex? |
With reference to crystal field splitting in octahedral complexes, my textbook shows the following table of distribution of $d$-orbital electrons in octahedral complexes, based on the energy difference of $t_{2g}$ and $e_g$ orbitals:
[Table](https://i.stack.imgur.com/rw6Kh.jpg)
Do ALL the $d$ orbital configuratio... |
The melting and boiling points of transition elements increases from scandium (1530 centigrade) to venadium (1917 centigrade). They increase because as we go across the group, we have more unpaired (free) electron.
But at chromium (1890 centigrade) however, the M.P decreases though it has more unpaired electrons tha... |
The melting and boiling points of transition elements increases from scandium ($1530^oC$) to vanadium ($1917^oC$). They increase because as we go across the group, we have more unpaired (free) electron.
But at chromium ($1890^oC$) however, the M.P decreases though it has more unpaired electrons than the previous ato... |
The melting and boiling points of transition elements increases from scandium ($1530^\mathrm{o}\:C$) to vanadium ($1917^\mathrm{o}\:C$). They increase because as we go across the group, we have more unpaired (free) electron.
But at chromium ($1890^\mathrm{o}\:C$) however, the M.P decreases though it has more unpaire... |
This answer is intended to supplement [Manishearth's earlier answer](http://chemistry.stackexchange.com/a/445/83), rather than compete with it. My objective is to show how octet rules can be helpful even for molecules that contain more than the usual complement of eight electrons in their valence shell.
I call it do... |
I have the following reaction:
$CH_2 (g) + 2O_2 (g) \rightarrow CO_2 (g) + 2H_2 O(l) $
How do I determine how many electrons are transferred in this reaction? More specifically, I need to know the value of $v_e$ which I am supposed to plug into the Nernst equation, which my textbook explains as the coefficient of... |
How many electrons are transferred in this redox reaction? |
I have the following reaction:
$CH_4 (g) + 2O_2 (g) \rightarrow CO_2 (g) + 2H_2 O(l) $
How do I determine how many electrons are transferred in this reaction? More specifically, I need to know the value of $v_e$ which I am supposed to plug into the Nernst equation, which my textbook explains as the coefficient of... |
I have the following reaction:
$CH_4 (g) + 2O_2 (g) \rightarrow CO_2 (g) + 2H_2 O(l) $
How do I determine how many electrons are transferred in this reaction? More specifically, I need to know the value of $v_e$ which I am supposed to plug into the Nernst equation, which my textbook explains as the coefficient of... |
What does the signals in a XPS spectrum mean? |
If electrolysis splits water, then that means that H2O is split into H and OH or O.
How come that if a water molecule is split at e.g. the negative pole (anode), only the O bubbles up. What happens to the H and/or OH? Do they react with the pole and stay there? |
If electrolysis splits water, why does only either hydrogen or water (but not both) occur on one pole? |
If electrolysis splits water, then that means that $\ce{H2O}$ is split into $\ce{H}$ and $\ce{OH}$ or $\ce{O}$.
How come that if a water molecule is split at e.g. the negative pole (anode), only the $\ce{O}$ bubbles up. What happens to the $\ce{H}$ and/or $\ce{OH}$? Do they react with the pole and stay there? |
you are quite right, XPS does measure the 'binding energy' of electrons. More specifically, XPS bombards a surface with X-rays and when those X-rays have sufficient energy they are able to sufficiently excite electrons to be emitted from the sample. Each peak in an XPS spectrum corresponds to the energy necessary to em... |
If electrolysis splits water, why does only either hydrogen or oxygen (but not both) bubble up on one pole? |
How is this an autocatalytic reaction? |
KeithS's answer is good for the saturated alkanes (generic formula $\ce{C_{n}H_{2n +2}}$). For other organic molecules...
Introducing unsaturation or heteroatoms makes it even more complicated. There are two "possible" structures for $\ce{C3H6}$ - [propene][1] and [cyclopropane][2] and three for $\ce{C3H4}$ - [propy... |
I have the following reaction:
$CH_4 (g) + 2O_2 (g) \rightarrow CO_2 (g) + 2H_2 O(l) $
How do I determine how many electrons are transferred in this reaction? More specifically, I need to know the value of $v_e$ which I am supposed to plug into the Nernst equation, which my textbook explains as the coefficient of... |
Given the standard enthalpy of formation of $AgNO_3 (aq) = -99$ kJ/mol and the standard enthalpy of formation of $Ag^+(aq) = +105$ kJ/mol, what's the standard heat of formation of $AgNO_3(aq)$?
How can I know this if the standard enthalpy of reaction is not known? This is self test 10.1 in Atkins, PC. |
Given the standard enthalpy of formation of $AgNO_3 (aq) = -99 kJ/mol$ and the standard enthalpy of formation of $Ag^+(aq) = +105 kJ/mol$, what's the standard heat of formation of $AgNO_3(aq)$?
How can I know this if the standard enthalpy of reaction is not known? This is self test 10.1 in Atkins, PC. |
Given the standard enthalpy of formation of $\ce{AgNO3(aq)} = -99 \text{ kJ/mol}$ and the standard enthalpy of formation of $\ce{Ag+(aq)} = +105 \text{ kJ/mol}$, what's the standard heat of formation of $\ce{AgNO3(aq)}$?
How can I know this if the standard enthalpy of reaction is not known? This is self test 10.1 in... |
Starting points for *[Quantum Theory of Atoms in Molecules][qtm]* (AIM) is electron density $\rho(r)$. It could be determined experimentally (X-ray diffractions). I want to know how can we estimate them *ab initio*. In **AIM**
it is often emphasized they they focus on density rather than wave function for later is jus... |
I have a program assignment here, and I was wondering if anyone can point me in the right direction as to where to start and how to approach problems like this.
Write a program that determines the molecular weight of a chemical compound based on the number of hydrogen, carbon, and oxygen atoms in the compound. You s... |
I have to write a Python program relating with molecular weight. Any insight? |
$$HCO_3^{-}(aq) + H_2O(l) <-> H_2CO_3(aq)+OH^-(aq)$$
I do not understand why this makes an Arrhenius base and why it doesn't form:
$$HCO_3^{-}(aq) + H_2O(l) <-> CO_3^{2-}(aq)+H_3O^+(aq)$$
Could someone explain this to me? |
How do you determine which chemical formula gains or loses an H+ in an equation? |
I'm writing a program which finds the number of accessible and inaccessible functional groups in molecules to give a metric of synthesizability. I was told in this question: http://chemistry.stackexchange.com/questions/4789/synthesizability-and-energy-minimization-of-a-structure/4791#4791 to
[Count the] "number of a... |
Starting point for *[Quantum Theory of Atoms in Molecules][qtm]* (AIM) is the electron density $\rho(r)$. It could be determined experimentally (X-ray diffractions). I want to know how can we estimate them *ab initio*. In **AIM**
it is often emphasized that the focus is on density rather than a wave function for the l... |
Both of these equations are valid, as $HCO_{3}^{-}$ is amphoteric (i.e. both an acid and a base).
To answer your question, one has to consider that the pKa value for $H_{2}CO_{3}$ is 6.37 and that for $HCO_{3}^{-}$ is 10.32. So if we started from "pure" $HCO_{3}^{-}$ (let's assume sodium bicarbonate) and add it to ... |
Given the standard enthalpy of formation of $\ce{AgNO3(aq)} = -99 \text{ kJ/mol}$ and the standard enthalpy of formation of $\ce{Ag+(aq)} = +105 \text{ kJ/mol}$, what's the standard heat of formation of $\ce{NO3^{-}(aq)}$?
How can I know this if the standard enthalpy of reaction is not known? This is self test 10.1 ... |
Is there any free moving electrons in metal vapor? |
Metals contain free moving electrons, in both the solid and liquid state. Does this happen when it is in vapor form? |
Are there any free electrons in metal vapor? |
$$\ce{HCO_3^{-}(aq) + H_2O(l) <-> H_2CO_3(aq) +OH^-(aq)}$$
I do not understand why this makes an Arrhenius base and why it doesn't form:
$$\ce{HCO_3^{-}(aq) + H_2O(l) <-> CO_3^{2-}(aq) +H_3O^+(aq)}$$
Could someone explain this to me? |
How do you determine which entity gains or loses an H+ in an equation? |
Both of these equations are valid, as $\ce{HCO3-}$ is amphoteric (i.e. both an acid and a base).
To answer your question, one has to consider that the $\rm pK_a$ value for $\ce{H2CO3}$ is 6.37 and that for $\ce{HCO3-}$ is 10.32. So if we started from "pure" $\ce{HCO3-}$ (let's assume sodium bicarbonate) and add it ... |
I have a program assignment here, and I was wondering if anyone can point me in the right direction as to where to start and how to approach problems like this.
> Write a program that determines the molecular weight of a chemical compound based on the number of hydrogen, carbon, and oxygen atoms in the compound. You... |
I recently conducted an experiment where I electrolyzed a solution of sodium chloride. I was using a copper coin as the anode, and I observed a pale blue precipitate in the cup when I was done with the experiment. I then deduced the following:
The chloride ions get oxidized at the anode: $2 Cl^- + 2 e^- \rightarrow ... |
Electrolysis: Water to Hydrogen gas? |
I was reviewing some analytical chemistry and stumbled upon a section that explained the imperfection of using a salt bridge.
It said that the using dissimilar ions is a problem because in, for example, the case of KCl the K+ and Cl- have different mobility and so you get regions that are rich in K+ and others rich... |
why do aqueous solutions always "have to be" electrically neutral? |
I was reviewing some analytical chemistry and stumbled upon a section that explained the imperfection of using a salt bridge.
It said that the using dissimilar ions is a problem because in, for example, the case of KCl the K+ and Cl- have different mobility and so you get regions that are rich in K+ and others rich... |
Why do aqueous solutions always have to be electrically neutral? |
I recently conducted an experiment where I electrolyzed a solution of sodium chloride. I was using a copper coin as the anode, and I observed a pale blue precipitate in the cup when I was done with the experiment. I then deduced the following:
The chloride ions get oxidized at the anode: $\ce{2 Cl^- \rightarrow Cl_2... |
I was told in this question: http://chemistry.stackexchange.com/questions/4789/synthesizability-and-energy-minimization-of-a-structure/4791#4791 to
[Count the] "number of accessible functional groups (alkenes, amines, alcohols, esters, etc) which make it easier to prepare, 5) number of inaccessible functional groups... |
> What you are asking amounts to the collected knowledge, wisdom, and intuition of the organic chemistry community. Your best bet will be to find an organic chemist, preferably one with a graduate degree, to work with you on this project. Said organic chemist can apply his/her knowledge/wisdom/intuition to each functio... |
> What you are asking amounts to the collected knowledge, wisdom, and intuition of the organic chemistry community. Your best bet will be to find an organic chemist, preferably one with a graduate degree, to work with you on this project. Said organic chemist can apply his/her knowledge/wisdom/intuition to each functio... |
So I understand, electrons exist in orbitals, mainly s, p, d, f and that when they bond with one another it will form sigma and pi bonds and that whether it bonds in a certain orientation a molecular bonding orbital or an anti bonding orbital will form.
What I DON'T understand is that when an element bonds it's ener... |
Say I have an effervescent tablet and I put in water. I thought that if I break the tablet in two halves it would dissolve quicker than with the whole table (without breaking), but it actually takes the same time.
What would be the scientific reason of this? |
Say I have an [effervescent][1] tablet and I put in water. I thought that if I break the tablet in two halves it would dissolve quicker than with the whole table (without breaking), but it actually takes the same time.
What would be the scientific reason of this?
[1]: http://en.wikipedia.org/wiki/Effervescen... |
Technically, it should dissolve faster, just like you thought! It will dissolve faster because there is a greater surface area : solution ratio (i.e. the broken edges, which used to be 'in the middle' of the tablet, are now exposed to the water). In general, the more surface area exposed, the faster it will dissolve.
... |
I am trying to transform a lipid with a tertiary alcohol into a carboxylic acid. Any suggestions? |
How to transform a tertiary alcohol to a carboxyl? |
The energy barrier for activation appears in the derivation of a bimolecular reaction through collision or transition state theory, but it seems that from looking at diagram such as this one ![enter image description here][1] it seems like the barrier to activation would be related to the energy required to break bonds... |
Is the activation barrier of a reaction related to the free energy or heat of formation of its reactants? |
I am trying to transform a lipid with a tertiary alcohol into a carboxylic acid.
More specifically, I want to convert to diplopterol (see below) into something homologous to cholesteryl hemisuccinate (see below).
**Any suggestions?**
*Diplopterol:*
![enter image description here][1]
*Cholesteryl hemisu... |
Why is it that the extent of racemisation is greater in $SN_1$ reaction caried out using polar protic solvent but the racemisation is not as extensive if aprotic solvent is used although the carbocation intermediate is common in both?
eg:- 2-Bromobutane is solvolysed with $H_2O$ and $CH_3OH$ but the racemisation is... |
Relative racemisation in SN1 reaction? |
I know this is broad so I will narrow:
Why does molten [PLA][1] stick to Aluminum?
I ask because I'm looking for a way to prevent/reduce the friction of the plastic inside the aluminum barrel of a 3D Printer. I believe that I can treat the surface of the aluminum with a High Temp enamel however I need to be sure of... |
Why does molten plastic (PLA) stick to metals (AL)? |
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