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Why are transition metal hydroxides insoluble? |
For instance, copper can form [Cu(H2O)6]2+ so it accepts 6 electron pairs from H2O molecules to form dative covalent bonds. However it has one electron in the 4s subshell and 10 in the 3d subshell. To which shell does it accept these electrons? Is it to the 4d subshell? And how are these accepted electrons arranged?
... |
How can transition metals form so many bonds with ligands? |
Larger value of b signifies that the size of the molecules is larger and hence the forces acting should become larger due to increased surface area.This should ensure easier liquefication. But my book says that smaller value of b corresponds to easier liquefication. Where am I am going wrong? |
Why does small value of van der Waals gas constant "b" ensure easier liquefication? |
I have long known that mixing bleach and peroxide produces oxygen gas:
$$\ce{NaOCl + H2O2 -> O2 + H2O + NaCl}$$
However I only recently learned that the specific form of oxygen produced by the reaction is [singlet oxygen](http://en.wikipedia.org/wiki/Singlet_oxygen):
$$\ce{NaOCl + H2O2 -> O2(a^1\Delta_{g}) + H... |
A unique demo for singlet oxygen? |
You got it wrong. In the first case (Zn in ZnSO4 and Cu in CuSO4) the eltrodes are connected through an external circuit (You see that bulb glowing?). But what this article is trying to say is that in the cell (Zn, Cu in H2SO4), if you leave the solution as it is without connecting externally, Zn having higher tendency... |
You got it wrong. In the first case (Zn in ZnSO4 and Cu in CuSO4) the electrodes are connected through an external circuit (You see that bulb glowing?). But what this article is trying to say is that in the cell (Zn, Cu in H2SO4), if you leave the solution as it is without connecting externally, Zn having higher tenden... |
You got it wrong. In the first case (Zn in $\ce{ZnSO4}$ and Cu in $\ce{CuSO4}$) the electrodes are connected through an external circuit (You see that bulb glowing?). But what this article is trying to say is that in the cell (Zn, Cu in $\ce{H2SO4}$), if you leave the solution as it is without connecting externally, Z... |
Here Cu plate is cathode and Zn plate is anode, it's written wrong in it. In the first case (Zn in $\ce{ZnSO4}$ and Cu in $\ce{CuSO4}$) the electrodes are connected through an external circuit (You see that bulb glowing?). But what this article is trying to say is that in the cell (Zn, Cu in $\ce{H2SO4}$), if you leav... |
WHAT IS THE REASON FOR THIS AZEOTROPE FORMATION? I MEAN WHY AT THAT COMPOSITION ONE COMPONENT ALONE CANNOT GO TO VAPOUR PHASE. IS THERE ANY EXTRA FORCE HOLDING THE TWO COMPONENTS TOGETHER AT THAT COMPOSITION? |
WHAT IS THE REASON FOR THIS AZEOTROPE FORMATION? |
What is the reason for this azeotrope formation? I mean why at that composition one component alone cannot go to vapour phase. Is there any extra force holding the two components together at that composition? |
What is the reason for this azeotrope formation? |
In most substituents , mesomeric effect is considered stronger and more dominating than the inductive effect .
A notable exception are the halogens .
The reason behind this has been well-explained [here][1].
I further had questions about the following:
- Since its about the EN , would all othe... |
In which all substituents does Inductive effect overpower Mesomeric effect? |
Here Cu plate is cathode and Zn plate is anode, it's written wrong in it. In the first case (Zn in $\ce{ZnSO4}$ and Cu in $\ce{CuSO4}$) the electrodes are connected through an external circuit (You see that bulb glowing?). But what this article is trying to say is that in the cell (Zn, Cu in $\ce{H2SO4}$), if you leav... |
I've read in book that the main factor for determining SN2 reaction rate is steric hindrance. The lesser it is the faster the reaction.
So consider this question:
![enter image description here][1]
As you can see , it is a question from the famous JEE exam in India. Anyway, I do not understand how S is the fastest ,... |
I realise that there is a similar question here http://chemistry.stackexchange.com/questions/7304/difference-between-sodium-ion-and-a-transition-metal-ion-dissolving-in-water and it seems to answer my question, however I was reading about how aluminion ions form complexes in water, and aluminium is not a transition met... |
Does sodium form complexes like transition metal ions? |
There are a number of factors that can influence the rate of an $\mathrm{S_{N}2}$ reaction. Solvent, leaving group stability, attacking group nucleophilicity, steric factors and electronic factors.
In the series of compounds you've presented, all of these parameters are held constant except for the steric and elect... |
There are a number of factors that can influence the rate of an $\mathrm{S_{N}2}$ reaction. Solvent, leaving group stability, attacking group nucleophilicity, steric factors and electronic factors.
In the series of compounds you've presented, all of these parameters are held constant except for the steric and elect... |
There are a number of factors that can influence the rate of an $\mathrm{S_{N}2}$ reaction. Solvent, leaving group stability, attacking group nucleophilicity, steric factors and electronic factors.
In the series of compounds you've presented, all of these parameters are held constant except for the steric and elect... |
About the first two, it's an exception to the rule that resonance dominates hyperconjugation.
About the last inequality, the vinyl cation is sp hybridized which means it is highly electronegative, and a positive charge on it will be very unstable.
About the middle inequality, the benzyl carbocation (with five res... |
[Surface passivation][1] is done to deal with "dangling bonds" (for example, $\mathrm{SiO_2}$ layer on top of a $\mathrm{Si}$ layer). But isn't the new surface will have dangling bonds on its own at the new formed surface?
[1]: https://en.wikipedia.org/wiki/Passivation_%28chemistry%29 |
How surface passivation works? |
I got this problem in school as a tool to get ready for International Chemistry Olympiad, but I have some problems with this challenge.
So, the problem is to calculate as precise as possible the Gibbs free energy for CaCO3 decomposition at 1200K.
I know that dG=dH-T*dS
But dS and dH are temperature dependant, so... |
I did the iodine clock reaction using sodium metabisulfite and potassium iodate. As I understand it, increasing concentration is supposed to speed up your reaction rate. I did 10 trials. The first 5 I varied the concentration of metabisulfite and kept the iodate constant. Trials 6-10 I varied the potassium iodate and k... |
What I thought was that graphite has van derr waal forces while diamond has covalent forces so diamond should be more stable. but the melting point of graphite is more than diamond which implies that it is thermodynamically more stable. I am thoroughly confused. So which is more stable ? |
The change in enthalpy of carbon in diamond form to graphite is negative .This suggests that graphite should be more stable than diamond. is it true? |
From http://chemistry.stackexchange.com/q/27455/1071 I confirmed that nitrogen is used to exclude oxygen - in order to prevent oxidation of the material.
Can CO<sub>2</sub> be substituted for nitrogen, or will the presence of carbon dioxide slow down the reaction (which is also causing carbon dioxide to be released)... |
Can decarboxylation be done under carbon dioxide? |
Question:
> In a cubic lattice of XYZ, X atoms are present at all corners except one corner which is occupied by Y atoms. Z atoms are present at face centres. What is the formula of compound? (Ans. X<sub>2</sub>YZ<sub>24</sub>)
My solution:
No. of X atoms in a unit cell = 7 * 1/8 = 7/8
No. of Y atoms ... |
Because
nitrogen is the standard inert gas in lab practice.
If You are "rich" You can use argon, carbon dioxide
is seldom used, because it won't work on alkaline
solutions.
> or will the presence of carbon dioxide slow down the reaction
first, what You presumbably mean is influencing the equilibrium
un... |
Larger value of b signifies that the size of the molecules is larger and hence the forces acting should become larger due to increased surface area.This should ensure easier liquefication. But my book says that smaller value of b corresponds to easier liquefication. Where am going wrong?
The book says "Chlorine is m... |
> $Z = 1 + (b - a/RT)/Vm + (b/Vm)^2 ...$
Going by virial equation of state, it seems like increasing the value of b will increase Z. Which means repulsive force will increase making the gas liquefaction difficult. Also for a = 0 and b = 0, the gas becomes ideal gas whose liquefaction is not possible, so I think what... |
In a hydrogen atom only 1s orbital is filled. Does this mean that the energies of all other orbitals are equal? If so,why?
|
Are the energies of orbitals that are not filled in an atom, equal? |
The electronic configuration of Fe is 1s2 2s2 2p6 3s2 3p6 4s2 3d6.
So after removing two electrons the configuration becomes:
1s2 2s2 2p6 3s2 3p6 3d6
But why cant the electrons rearrange themselves to give a more stable
1s2 2s2 2p6 3s2 3p6 4s1 3d5 configuration?
|
What is the electronic configuration of Fe(II) ion? |
I was reading about electrochemical cells and I really don't understand why a salt bridge is needed. Can't you just combine the solutions? I've found a lot of webpages explaining electrochemical cells but strangely enough none of them seem to find this important enough to explain. All thoughts appreciated :)
|
Why use a salt bridge at all in an electrochemical cell? |
My book says: frequency is considered as the only REAL characteristics of electromagnetic radiation, because it is unchangeble if the radiation comes up with some other environment, while the wavelength and the wavelength number do change. How can wavelength change and the frequency not ? The formula tells us very clea... |
Frequency, the only real characteristics of electromagnetic radiation ?? |
I did the iodine clock reaction using sodium metabisulfite and potassium iodate. As I understand it, increasing concentration is supposed to speed up your reaction rate. I did 10 trials. The first 5 I varied the concentration of metabisulfite and kept the iodate constant. Trials 6-10 I varied the potassium iodate and k... |
Given the simple first order reaction $ A -> P $ derive the integrated rate law.
$$\frac{d[A]}{dt} = -k[A]$$
Collect terms:
$$\frac{d[A]}{[A]} = -kdt$$
Now for the bit I need help with, the integration:
Apparently the integrated form of $\frac{d[A]}{[A]}= ln[A]$ but I'm struggling to see exactly how.
The... |
Given the simple first order reaction $ A -> P $ derive the integrated rate law.
$$\frac{d[A]}{dt} = -k[A]$$
Collect terms:
$$\frac{d[A]}{[A]} = -kdt$$
Now for the bit I need help with, the integration:
Apparently the integrated form of $\frac{d[A]}{[A]}= ln[A]$ but I'm struggling to see exactly how.
The... |
Do atoms combine with the nearest atoms possible because of lower delta E (less energy needed to form a stable nucleus)? |
How do atoms combine? |
Given the simple first order reaction $\ce{A -> P}$ derive the integrated rate law.
$$\frac{d[A]}{dt} = -k[A]$$
Collect terms:
$$\frac{d[A]}{[A]} = -kdt$$
Now for the bit I need help with, the integration:
Apparently the integrated form of $\frac{d[A]}{[A]}= ln[A]$ but I'm struggling to see exactly how.
... |
I did the iodine clock reaction using sodium metabisulfite and potassium iodate. As I understand it, increasing concentration is supposed to speed up your reaction rate. I did 10 trials. The first 5 I varied the concentration of metabisulfite and kept the iodate constant. Trials 6-10 I varied the potassium iodate and k... |
Under constant pressure (and only PV work), change in enthalpy can be shown to equal change in heat. If enthalpy is not meaningful outside of constant pressure, then why not use heat instead? So I think it must be meaningful outside of constant pressure scenarios, but I couldn't figure it out myself. Can someone help?
... |
What is the significance of enthalpy definition not under constant pressure? |
I bought a phosphate buffer from Sigma/Fluka (73212-1L) containing potassium dihydrogen phosphate ($KH_2PO_4$) and disodium hydrogen phosphate ($Na_2HPO_4$).
It is at pH 8.0 but they do not provide the phosphate concentration. Can I determine it from pH? |
Determining concentration of phosphate buffer from pH? |
I bought a phosphate buffer from Sigma/Fluka (73212-1L) containing potassium dihydrogen phosphate ($KH_2PO_4$) and disodium hydrogen phosphate ($Na_2HPO_4$).
It is at pH 8.0 but they do not provide the phosphate concentration. Can I determine it from pH via titration?
This table shows the concentrations for a 0.... |
I'd like someone to explain, scientifically, what makes some baby clothes' stains so hard to remove, and what the right way to treat the stains is, chemistry-wise. A lot of internet sites have solutions (pardon the pun) that are 'my experience' and anecdotal, which is better than nothing, but not always transferable (a... |
I was wondering why temperature regulation is an important factor in producing explosives. I know many are exothermic reactions but what would happen if you did not use an ice bath and allow the temperature to go too high? Would it explode? Considering the explosive substance has not already been formed in the reaction... |
I want to make an algorithm that will give me the boiling temperature of a substance as a function of pressure, the critical temperature of a substance, and the critical pressure of a substance. I believe this can be done using a combination of the Peng-Robinson Equation of state and the Clayperon or Clausius-Clayperon... |
How can I calculate the boiling temperature of a pure substance as a function of pressure? |
I was wondering why temperature regulation is an important factor in producing explosives. I know many are exothermic reactions but what would happen if you did not use an ice bath and allow the temperature to go too high (Considering the explosive substance has not already been formed in the reaction)? Would it explod... |
Why does bond angle decrease in the order H₂O, H₂S, H₂Se? |
Two fluids with same reduced volume and temperature have the same reduced pressure.
Two fluids with same reduced pressure and temperature have the same compression factor.
What justifies these two statements and why exactly are both saying the same thing? |
What is the justification behind the principle of corresponding states? |
Why is salt needed when using vinegar to clean pennies? |
Okay, so this question may be a little elementary, but I still do not understand how you can work out which element will more readily react with another element.
For an example I have Lithium (Li) and Sodium (Na) and I am trying to work out which element will be more reactive with Oxygen.
How do I manage to work... |
I do not understand how you can work out which element will more readily react with another element.
For an example, I have Lithium (Li) and Sodium (Na) and I am trying to work out which element will be more reactive with Oxygen.
How do I manage to work that out?
Please answer in the most simple and easy way ... |
In my textbook there is the following problem:
How many moles of $NH_4CL$ must be added to $2.0 L$ of $0.10$ $M$ $NH_3$ to form a buffer with $pH=9$? Assume the addition does not change the volume of the solution significantly.
The solution given is as follows:
The equilibrium between $NH_3$ and $NH4^+$ is giv... |
How many moles $NH_4Cl$ must be added to $NH_3$ to create buffer with $pH=9$? |
![enter image description here][1]
I have no idea how to determine the substituents on the aromatic ring from NMR diagram. There is (might be ) a triplet on my NMR around 7.59-7.65ppm which has 4 hydrogens in the same environment. If so, there must be two ortho substituents on two aromatic rings but I think the... |
How to determine ortho/para substituents on the aromatic ring via NMR ? |
In [this rather shaky Facebook video](https://www.facebook.com/video.php?v=977834295591048) (sorry I can't provide a better link), a science teacher takes a burning beaker of something and spills it out onto the floor. It then proceeds to shoot fire out in all directions, and we can see embers burning themselves out, ... |
What is involved in this firey demonstration? |
In my textbook there is the following problem:
>How many moles of $\ce{NH_4CL}$ must be added to $2.0 L$ of $0.10$ $M$ $\ce {NH3}$ to form a buffer with $pH=9$? Assume the addition does not change the volume of the solution significantly.
The solution given is as follows:
The equilibrium between $\ce{NH_3}$ an... |
In my textbook there is the following problem:
>How many moles of $\ce{NH4Cl}$ must be added to $2.0~\mathrm{L}$ of $0.10~\mathrm{M}$ $\ce{NH3}$ to form a buffer with $pH=9$? Assume the addition does not change the volume of the solution significantly.
The solution given is as follows:
The equilibrium between ... |
How many moles NH₄Cl must be added to NH₃ to create buffer with pH=9? |
I'm preparing a chemistry show where I end the show with yellow powder bang.
The powder is a mixture of:
$$\ce{K2CO3 + KNO3 + S} $$
My question is, what's the reaction between these chemicals?
|
What is the cemistry behind the reaction of KNO₃, K₂CO₃ and Sulfur? |
![compound][1]
In this compound both the cyclic and acyclic have 3 carbons , hence a tie.
Even the substituent comes on the 2nd position in both cases .
So should the main chain be the cyclic one ? (since for a tie Cyclic>Acyclic is the rule.)
[1]: https://i.stack.imgur.com/EENham.jpg |
I was wondering why temperature regulation is an important factor in producing explosives. I know many are exothermic reactions but what would happen if you did not use an ice bath and allow the temperature to go too high (Considering the explosive substance has not already been formed in the reaction)? Would it explod... |
I was wondering why temperature regulation is an important factor in producing explosives. I know many are exothermic reactions but what would happen if you did not use an ice bath and allow the temperature to go too high (Considering the explosive substance has not already been formed in the reaction)? Would it explod... |
What is the chemistry behind the reaction of KNO₃, K₂CO₃ and Sulfur? |
I learnt that Gibbs free energy is the maximum amount of non-expansion work.
But the phrase non expansion work confuses me. Work is defined as pressure times change in volume. If there is no expansion, how can work be done? |
What is non-expansion work? |
We use an levitating furnace to heat samples of refractory ceramics up to approx 3000C. Its for research purposes, so the samples are small (2mm) beads. These are balanced on a jet of argon and heated with CO2 lasers.
Here is a paper which talks about the technique:
http://cadair.aber.ac.uk/dspace/bitstream/handle/... |
We use an levitating furnace to heat samples of refractory ceramics up to approx $3000~^\circ\mathrm{C}$. Its for research purposes, so the samples are small (2 mm) beads. These are balanced on a jet of argon and heated with $\ce{CO2}$ lasers.
Here is a paper which talks about the technique:
[D. Langstaff, M. Gun... |
The Gibbs energy increases from the reactants to the transition state, but according to the Second Law of Thermodynamics, entropy of the universe can only increase. Why is the transition state possible then? |
If Gibbs energy of activation is positive, how is the change to the transition state possible? |
In the mechanism of reduction of amide with LiALH4 ([here][1]), the first step is addition of hydride on carbonyl group. But why doesn't the hydride ion abstract a proton from NH2? Since acid base reactions are faster than nucleophilic addition.
[1]: http://chemwiki.ucdavis.edu/Organic_Chemistry/Amides/Reactions... |
In the mechanism of reduction of amide with $\ce{LiAlH_4}$ ([here][1]), the first step is addition of hydride on carbonyl group. But why doesn't the hydride ion abstract a proton from $\ce{-NH2}$? Since acid base reactions are faster than nucleophilic addition.
[1]: http://chemwiki.ucdavis.edu/Organic_Chemistry/... |
I've seen a "2.303" term multiplied to *R* in Van't Hoff equation several times.
Here is one example:
http://en.wikipedia.org/wiki/Van_%27t_Hoff_equation#Error_propagation
> ΔH<sup>0</sup> = 2.303 R (logK<sub>1</sub> - logK<sub>2</sub>)/(1/T<sub>2</sub>-1/T<sub>1</sub>)
What is this number and where does it... |
What's the source of "2.303" in Van't Hoff equation? |
In [reduction of carboxylic acid][2] with $\ce{LiAlH_4}$ the first step is deprotonation.
But in the mechanism of reduction of amide with $\ce{LiAlH_4}$ ([here][1]), the first step is addition of hydride on carbonyl group. Why doesn't the hydride ion abstract a proton from $\ce{-NH2}$? Since acid base reactions ar... |
This weekend I accidentally left a glass of water on my kitchen table for a few days while I was out of town. Unsurprisingly, bubbles formed on the walls.
As I understand from the last time I attended a chemistry class quite a while ago, this happens due to water self-ionizing (at about a ratio of $10^{-14}$ if I ... |
Does self-ionization happen uniformly in water? |
What are the oxidation states of the two inequivalent sulfur atoms of the $\ce{S2O3^{2-}}$ molecule?
For all I know is that Lewis Structure does matter in most of the cases.
|
Where do the bubbles in a glass of water come from? |
This seems counter intuitive to me since ionic radius increases with increasing coordination number. Surely the solid doesn't expand under high pressure? Can you explain? |
Why do ionic solids change to a structure with a higher coordination number at high pressures? |
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