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You simply build the half reactions and add them up so you can see how many moles of hydrogen gas are produced by a mole of Aluminium being oxidised. (Note: Your first equation is unbalanced.)
\begin{aligned}\ce{
(1)&& Al + 6H2O &-> Al(OH2)_{6}^{3+} + 3e^{-}&|\cdot2\\
+ (2)&& 2H3+O + 2e^{-} &-> H2 ^ + 2H2O &|\cdot3\... |
I have looked at several sources including:
Khan Academy
https://www.khanacademy.org/science/chemistry/acids-and-bases/v/buffers-and-hendersen-hasselbalch
ChemCollective:
http://chemcollective.org/activities/tutorials/buffers/buffers3
And the answer to similar question:
http://chemistry.stackexchange... |
Do buffers only work for species of the opposite variety? (I.e. weak acids buffer strong bases and vice versa) |
Writing out the equilibrium expression for a weak acid in solution:
$$[\ce{H3O+}] = K_a\frac{[HA]}{[A^-]}$$
Buffers need to keep the concentration of the weak acid to it's conjugate base similar in order for it be effective.
Let's say you add a small amount of base. Some of the $\ce{HA}$ molecules are convert... |
I have looked at several sources including [Khan Academy](https://www.khanacademy.org/science/chemistry/acids-and-bases/v/buffers-and-hendersen-hasselbalch), [ChemCollective](http://chemcollective.org/activities/tutorials/buffers/buffers3) and the answer to a similar question:
http://chemistry.stackexchange.com/questi... |
I am a physicist, not a chemist. I'm trying to get a basic understanding of the reactions taking place in a battery using a saltwater electrolyte with copper and zinc terminals. I'm writing a general science level article about it. I have found that the reactions taking place at the terminals are:
\begin{aligned}
... |
I have looked at several sources including [Khan Academy](https://www.khanacademy.org/science/chemistry/acids-and-bases/v/buffers-and-hendersen-hasselbalch), [ChemCollective](http://chemcollective.org/activities/tutorials/buffers/buffers3) and the answer to a similar question:
http://chemistry.stackexchange.com/questi... |
How can I theoretically predict the time needed to photolyze n moles of $\ce{AgF}$? (with UV) (this is not a homework question)
The photolysis of $\ce{AgF}$ requires UV light - but I don't know which wavelength the UV must be at for the optimal photolysis. Then if the wavelength is known I can calculate the energy o... |
How can I figure out the degeneracy of the d orbitals for a site that has a given point group? Specifically I'm interested in $D_{3d}$ and $D_{3h}$, but it would be good to know how to do it in the general case. |
I am dealing with the iodine clock reaction, which has the half-reactions:
$$\begin{align}&\ce{H_2O_2 (aq) + 2I^- (aq) \to I_2 (s) + 2 OH^- (aq)} & (\text{slow}) \\ &\ce{I_2 (s) + 2S_2O_3^{-2} (aq) \to{} 2I^- (aq) + S_4O_6^{-2} (aq)} & (\text{fast}) \end{align}$$
Now, I have to find the rate law. What I did was 4 ... |
The changing of the colour of $\ce{NO2}$ is because of a change in temperature, resp. heating and cooling? |
$$\begin{align}\ce{2A + 2B &-> 2C }\\ \ce{A + B &-> C}\end{align}$$
Why does the equilibrium constant change?
And why the rate of the first reaction square the rate of the second? I understand it mathematically, but logically and scientifically I can't understand it at all. |
Rate will not be square in most of the cases and who said so? The equilibrium constant scientifically changes because Gibb's free energy is extensive quantity and it is related to equilibrium constant through relation that you might know $\Delta G=\Delta G^\circ +\mathcal{R}T\ln Q $. Where $Q$ is reaction quotient whic... |
I just learned about rate and order... I just want to confirm if these three ideas are correct:
1. If the first elementary step is the slow step, will the stoichiometric coefficients of the reactants in the rate determining step (RDS) be EQUAL to the order the concentration of the reactants in the rate equation is r... |
> Changes in which factors affect both the rate and the rate
constant of a first order reaction?
>
I. temperature
>
>II. concentration
>(A) I only (B) II only
(C) Both I and II (D) Neither I nor II
I would think that the answer would be (C), both temperature and concentration.
Concentration would ... |
Compounds with triple bonds generally seem to be unstable. $\ce{HCN}$ and $\ce{C2H2}$ are high-energy, relatively short-lived molecules that will readily polymerise or react with other organic molecules. My naïve mental picture is that they don't really want to have a triple bond because the geometry makes it awkward, ... |
Why is $\ce{N2}$ stable but $\ce{HCN}$ and $\ce{C2H2}$ unstable? |
Why is N₂ stable but HCN and C₂H₂ unstable? |
The amount of water(g) that air can accommodate depends on temperature. The absolute humidity then is defined as the percentage of water to air and decreases when the temperature decreases. The relative humidity is the ratio between the current and the maximum humidity, which increases with decreasing temperature. The ... |
Why can air accomodate more water when the air has a higher temperature? |
I think this question can be answered reasonably well with thermodynamic considerations. When we say something is stable, it is (or should be) assumed that the compound does not engage in a chemical reaction. It is important when we discuss the stability of compounds to focus not only on the compound itself but *what... |
![enter image description here][1]
[1]: https://i.stack.imgur.com/joOZ5.png
I am trying to assign the peaks here to dimethylphenylphatalate but all the benzene rings are throwing me off. All I can get is that the further most signal is the carbonyl carbon(168.71) and the one prior to that(143.27) might be the... |
C-13 NMR of DImethyl 3,4,5,6 tetraphenylphthalate? |
![enter image description here][1]
[1]: https://i.stack.imgur.com/joOZ5.png
I am trying to assign the peaks here to dimethylphenylphatalate but all the benzene rings are throwing me off. All I can get is that the further most signal is the carbonyl carbon (168.71) and the one prior to that (143.27) might be t... |
13C NMR of dimethyl 3,4,5,6-tetraphenylphthalate? |
Why can air accommodate more water when the air has a higher temperature? |
The process I have seen in class to activate a carbonyl function is acetalisation.
One of the steps involved is the following :
![http://i.imgur.com/WA0W7bC.png][1]
So I was wondering, is that a $S_N1$ or a $S_N2$ ?
(PS : drawing molecules with paint is awful, anyone knows a good free molecules drawe... |
Does this activation of carbonyls usually involve a $S_N1$ or a $S_N2$? |
The instructions ask to write a balanced equation for:
Iron(s) + copper(II) sulfate(aq) ->
If I used Iron(II) I get:
Fe + CuSO4 -> FeSO4 + Cu
and if I used Iron(III)
Fe + CuSO4 -> Fe2(SO4)3 +Cu
(Before balancing).
Is there a way to determine which one I am supposed to use?
|
Which Ion of Iron to Use? |
The instructions ask to write a balanced equation for:
$\ce{Iron(s) + copper(II) sulfate(aq) -> \;?}$
If I used Iron(II) I get:
$\ce{Fe + CuSO4 -> FeSO4 + Cu}$
and if I used Iron(III)
$\ce{Fe + CuSO4 -> Fe2(SO4)3 +Cu}$
(Before balancing).
Is there a way to determine which one I am supposed to use?... |
Which ion of iron to use? |
![enter image description here][1]
[1]: https://i.stack.imgur.com/joOZ5.png
I am trying to assign the peaks here to dimethylphenylphatalate but all the benzene rings are throwing me off. All I can get is that the further most signal is the carbonyl carbon (168.71) and the one prior to that (143.27) might be t... |
$\ce{^13}$C NMR of dimethyl 3,4,5,6-tetraphenylphthalate? |
![enter image description here][1]
[1]: https://i.stack.imgur.com/hxa0p.png
Regarding this question, how can one solve this without access to thermodynamic data?
I suppose we should keep the following information in mind:
1) Double bonds are not double the strength of single bonds. Same goes for trip... |
Why does calcium carbonate, when heated strongly, decompose into calcium oxide and carbon dioxide?
What is the mechanism? Can someone illustrate the means by which this happens? What bonds/associations are broken?
![enter image description here][1]
[1]: https://i.stack.imgur.com/x9W5s.png
I'm guessing ... |
Why does calcium carbonate decompose into calcium oxide? |
Why does calcium carbonate, when heated strongly, decompose into calcium oxide and carbon dioxide?
What is the mechanism? Can someone illustrate the means by which this happens? What bonds/associations are broken?
![enter image description here][1]
[1]: https://i.stack.imgur.com/x9W5s.png
I'm guessing ... |
The process I have seen in class to activate a carbonyl function is acetalisation.
One of the steps involved is the following :
![http://i.imgur.com/WA0W7bC.png][1]
So I was wondering, is that a $\ce{S_{N}1}$ or a $\ce{S_{N}2}$ ?
(PS : drawing molecules with paint is awful, anyone knows a good free m... |
Does this activation of carbonyls usually involve a SN1 or a SN2? |
Compounds with triple bonds generally seem to be unstable. $\ce{HCN}$ and $\ce{C2H2}$ are high-energy, relatively short-lived molecules that will readily polymerise or react with other organic molecules. My naïve mental picture is that they don't really want to have a triple bond because the geometry makes it awkward, ... |
I think this question can be answered reasonably well with thermodynamic considerations. When we say something is stable, it is (or should be) assumed that the compound does not engage in a chemical reaction. It is important when we discuss the stability of compounds to focus not only on the compound itself but *what... |
Is it
$\ce{O2(g) + 4H^+(aq) + 4e^- \rightarrow 2H_2O(l)}$
and are there multiple types of ORR?
See here for context: http://www.nature.com/srep/2014/140122/srep03821/full/srep03821.html |
What exactly is the "oxygen reduction reaction"? |
Are they thought to continuously pop in and out of existence at various points inside the orbital defined by probabilities or do they follow definite paths that are made fuzzy by the Heisenberg uncertainty principle?
I sometimes find myself as thinking of the electron cloud as a gas with varying charge density corresp... |
#Toxicity of tobacco combustion products in different phases
For answering your question I think is better split it in two. First thing you need to understand that toxicity depends on **the method of administation** of the toxic agent. Tobacco smoke is a physical state of the tobacco combustion products. It is an aero... |
What is the reason for anomalous expansion of water? Why don't it simply expands on heating or contract on cooling. Why it shows anomalous behavior at 4 degree centigrade? Why not on 4,6 or 10 (or whatever) degree centigrade? |
What is the reason for anomalous expansion of water? |
The [interpretation of quantum mechanics][1] is an unresolved issue in physics and philosophy.
>I sometimes find myself as thinking of the electron cloud as a gas with varying charge density corresponding to the shape of the atomic orbital.
This was Schrodinger's original interpretation when he developed/postula... |
So, the first question to ask would be: how "anomalous" is change in the thermal expansion coefficient? It turns out that for most real materials the coefficient of thermal expansion is not a constant, and takes on both positive (expansion) and negative (contraction with increasing temperature) values. For silicon as... |
Solubility of p-nitrophenol in various substances? |
So I had an organic chemistry lab where we had to dissolve p-nitrophenol in water, dilute $\ce{NaHCO3}$, dilute $\ce{NaOH}$, and dilute $\ce{HCl}$ to test for solubility.
The p-nitrophenol dissolved in everything but water. I just want to make sure if these results are theoretically correct. From what I understand,... |
Recently the question was asked, "[Is Bond Formation “Strictly” Exothermic?][1]" As a corollary to that question, what is the relationship between entropy and bond formation? Does entropy always decrease when a chemical bond is formed?
[1]: http://chemistry.stackexchange.com/questions/13536/is-bond-formation-s... |
Can Entropy Increase During Bond Formation? |
Recently the question was asked, "[Is Bond Formation “Strictly” Exothermic?][1]" As a corollary to that question, what is the relationship between entropy and bond formation? Does the entropy of the bond formation reaction always decrease when a chemical bond is formed?
[1]: http://chemistry.stackexchange.com/... |
Why is the $\ce{sp^2}$ hybridized nitrogen atom in guanidine the most basic?
![enter image description here][1]
[1]: https://i.stack.imgur.com/gYnIC.png
I know that as a general guideline, $\ce{sp^3}$ hybridized atoms are more basic than $\ce{sp^2}$. Bases are electron pair donors; having the electrons fu... |
When the diazonium ion couples with dimethylaniline why is para position favored ? Is it simply because of the steric factors or does electric factors play a part in it ? What I mean by electric factors is that benzene rings prefer the orto-para positions due to some of the resonance structures have a cation directly n... |
Why does diazo coupling prefer the para position? |
Why is the $\ce{sp^2}$ hybridized nitrogen atom in guanidine the most basic?
![enter image description here][1]
I know that as a general guideline, $\ce{sp^3}$ hybridized atoms are more basic than $\ce{sp^2}$. Bases are electron pair donors; having the electrons further away from the nucleus makes donation eas... |
For simple acid/base reactions - i.e. those involving inorganic compounds - does activation energy ever play in reactions?
Or can we ignore kinetics entirely and just consider thermodynamic factors such as conjugate stability?
I'd be very interested if there were some book or article examining inorganic molecul... |
Just as HArF was synthetized...Could something like Li-Ar-Li exist with AXE geometry AX2E3? Any orher argon compund proposals out there? |
How many argon compounds are theoretically and experimentally available? |
Just as HArF was synthetized...Could something like $ \ce{Li-Ar-Li}$ exist with AXE geometry AX2E3? Any orher argon compund proposals out there? |
Just as HArF was synthesized...Could something like $\ce{Li-Ar-Li}$ exist with AXE geometry $\ce{AX2E3}$? Any other argon compound proposals out there? |
Are the following two compounds isomers?
> (A) $CH_{3}-CO-CH_{2}-CH_{2}-CH_{2}-CH_{2}-OH$
> (B) $CH_{3}-CH_{2}-CH_{2}-CH_{2}-CH_{2}-COOH$
Although they have the same molecular formula ($C_{6}H_{12}O_{2})$, I think that this two compounds are not isomers.
|
Are the following two compounds isomers? |
What about JMol ?
http://jmol.sourceforge.net
It opens .Mol and a slew of other formats in Java which is fairly widely compatible. Open-source too. |
The electronic conductance of a metal depends on its density.Does this mean that if we increase the density of the metal,its electronic conductance will increase?How does it happen? |
how does electronic conductance of a metal change with density? |
Why solubility of Group II hydroxides increase down the group and sulphates decrease down the group? |
When NCl3 is dissolved in water, NH3 and HOCl is formed.
Can you please explain me whether formed solution is acid or basic or neutral? thank you! |
NCl3 + H2O = NH3 + HOCl , the resulted solution is acidic or basic?neutral? |
When $\ce{NCl3}$ is dissolved in water, $\ce{NH3}$ and $\ce{HOCl}$ is formed.
Can you please explain me whether formed solution is acid or basic or neutral? thank you! |
$\ce{NCl3 + H2O -> NH3 + HOCl}$ , the resulting solution is acidic, basic or neutral? |
Why is it that $pK_{\ce{a-HF}} \lt pK_{\ce{a-HCl}}\lt pK_{\ce{a-HBr}}\lt pK_{\ce{a-HI}}$, although the electronegativity decreases? The more electronegative the accompanying atom of hydrogen is, the lower is the energy of the $\sigma^\ast$ bond, the lower the energy of the $\sigma^\ast$ bond, the easier is it for nucle... |
You cannot change the density of a metal without also changing other properties.
Brass is a mixture of several elements. It can have different densities depending on the mixture of the elements. I haven't researched it, but the electronic conductance would likely be different for each type of brass.
Do you have ... |
Why is it that $pK_{\ce{a-HF}} \lt pK_{\ce{a-HCl}}\lt pK_{\ce{a-HBr}}\lt pK_{\ce{a-HI}}$, although the electronegativity decreases? The more electronegative the atom accompanying hydrogen, the lower the energy of the $\sigma^\ast$ bond. The lower the energy of the $\sigma^\ast$ bond, the easier it is for nucleophiles t... |
Just as HArF was synthesized...Could something like $\ce{Li-Ar-Li}$ exist with AXE geometry $\ce{AX2E3}$? Any other argon compound proposals out there?
I also known that there are some posible excimers like LiAr and KrF (maybe $KrF_2$). Can they be considered covalent compounds, even if explained via excited dimers/... |
I think i Know what these mean, each row on the periodic table has a new shell of electrons, a subshell is e.g. 1s, 2s, 2p, 3s, 3p, etc and energy levels are the same as shells whilst orbitals are the same as subshells. Is this correct or totally wrong? |
Less electronegative atom is the central atom.N is more electronegative than Cl as Cl has larger atomic radius.So why in NCl3,N is the central atom? |
Less electronegative atom is the central atom. $\ce{N}$ is more electronegative than $\ce{Cl}$ as $\ce{Cl}$ has larger atomic radius. So why in $\ce{NCl3}$, $\ce{N}$ is the central atom? |
I am pharmacy student and would like to work in the field of drug design. We learn to work with the programs but thats not enough for me. I want to learn the theoretical principles of computational chemistry and develop software themselves, or at least parts of it.
However, I have a few questions:
Where do I star... |
For example like HCl, why isn't it a Hydrogen Bond? |
How would you know if ... is H-Bond or Perm Dipole or Induced Dipole? |
My freshwater fish tank has a PH of 5.8 and a KH value in excess of 40 or 720+ppm while still maintaining a water hardness of 20 ppm or GH< 1 now im a math/phsyics student but ive taken both first year chem class at university so i expect to follow most basic ideas pertaining to chemistry but this doesnt make alot of s... |
Why is it that $pK_{\ce{a-HF}} \lt pK_{\ce{a-HCl}}\lt pK_{\ce{a-HBr}}\lt pK_{\ce{a-HI}}$, although the electronegativity decreases? The more electronegative the atom accompanying hydrogen, the lower the energy of the $\sigma^\ast$ bond. The lower the energy of the $\sigma^\ast$ bond, the easier it is for nucleophiles t... |
My freshwater fish tank has a PH of 5.8 and a KH value in excess of 40 or 720+ppm while still maintaining a water hardness of 20 ppm or GH< 1 now im a math/phsyics student but ive taken both first year chem class at university so i expect to follow most basic ideas pertaining to chemistry but this doesnt make alot of s... |
Why is it that $pK_{\ce{a-HF}} \lt pK_{\ce{a-HCl}}\lt pK_{\ce{a-HBr}}\lt pK_{\ce{a-HI}}$, although the electronegativity decreases? The more electronegative the atom accompanying hydrogen, the lower the energy of the $\sigma^\ast$ bond. The lower the energy of the $\sigma^\ast$ bond, the easier it is for nucleophiles t... |
Why is it that $pK_{\ce{a-HF}} \lt pK_{\ce{a-HCl}}\lt pK_{\ce{a-HBr}}\lt pK_{\ce{a-HI}}$, although the electronegativity decreases? The more electronegative the atom accompanying hydrogen, the lower the energy of the $\sigma^\ast$ bond. The lower the energy of the $\sigma^\ast$ bond, the easier it is for nucleophiles t... |
![enter image description here][1]
[1]: https://i.stack.imgur.com/l7G8s.png
Why is the above massaging of various K expressions valid? Something in me says "Hess's Law." But then doesn't that deal with enthalpy? What's the true reason? |
Why May K Expressions Be Manipulated As Such? |
Fe, Mg, Ni, Pb, Sn, and Zn all react when they (in solid form) are submerged in an acid solution with the presence of a strong acid like HCL, but silver and copper do not.
I have examined the electronegativity values and both Ag's and Cu's electronegativity value is only different from Ni by 0.1 on the Pauling scal... |
Why is it that neither silver nor copper react with a strong acid? |
For the reaction of silver and hydrochloric acid to form silver chloride: would the following be the correct way to couple the below two half reactions?
$\ce{2Ag(s) + 2Cl^- ->2AgCl(s) + 2e^-} ~~E^0 =-0.222 ~V$
$\ce{2e^- + 2H_3^+O -> H_2 + H_2O}{ ~~E^0 =0.000~ V}$
Add the above:
$\ce{2H_3^+O +2Ag(s) + 2Cl^-... |
This will involve some degree of hand-waving. Let me first limit the analysis to the transition metals so that more effective comparisons can be made.
The reaction between a metal and an acid requires the metal to be oxidized, i.e. lose electrons to the acid, creating positively-charged metal ions in solution. The g... |
I was reviewing my grad Thermodynamics textbook to go over a concept that I never learned well: the Lattice model. One set of equations (Ref 1) has:
$zN_1=2N_{11}+N_{12}$
$zN_2=2N_{22}+N_{12}$
where $z$ is the coordination number, OR the number of nearest neighbors (defined twice).
My trouble is a simple t... |
In the lattice model, what's a nearest neighbor? |
I was reviewing my grad Thermodynamics textbook to go over a concept that I never learned well: the Lattice model. One set of equations<sup>1</sup> has:
$zN_1=2N_{11}+N_{12}$
$zN_2=2N_{22}+N_{12}$
where $z$ is the coordination number, OR the number of nearest neighbors (defined twice).
My trouble is a simp... |
$\ce{Fe}$, $\ce{Mg}$, $\ce{Ni}$, $\ce{Pb}$, $\ce{Sn}$, and $\ce{Zn}$ all react when they (in solid form) are submerged in an acid solution with the presence of a strong acid like $\ce{HCL}$, but silver and copper do not.
I have examined the electronegativity values and both $\ce{Ag}$'s and $\ce{Cu}$'s electronegati... |
$\ce{Fe}$, $\ce{Mg}$, $\ce{Ni}$, $\ce{Pb}$, $\ce{Sn}$, and $\ce{Zn}$ all react when they (in solid form) are submerged in an acid solution with the presence of a strong acid like $\ce{HCl}$, but silver and copper do not.
I have examined the electronegativity values and both $\ce{Ag}$'s and $\ce{Cu}$'s electronegati... |
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