instruction stringlengths 15 21.8k |
|---|
How do you calculate how much energy is needed to break a water molecule into its constituent atoms?
*note*
This is not homework. I just want to know what is required to get hydrogen out of water. |
What state of matter are phosphomonoesterases? I am not a biochemist; while I've found various lists of such enzymes, and plenty of (to me) barely comprehensible articles describing their production, it's not clear to me whether the final product in isolation is a solid, liquid, or gas.
More generally, is there som... |
Are phosphomonoesterases solid? |
My questions relates to the fundamental concept of electrochemistry, more specifically the electrode potentials.
**1)** First, why is there a potential difference at the interface of two phases? Considering the simplest case of a metal rod dipped in the solution of its ions, why should there be a potential diffe... |
Electrode potentials at interfaces? |
There are a bunch of of sub parts to these questions; let me see if I can tease some of them out.
##Why does a potential difference occur at an interface?##
The easiest way to answer this question is through thermodynamics. If we consider the situation of a reactive metal rod (e.g. magnesium) being exposed to wate... |
How can I calculate the energy of a solution by knowing all of it's elements? |
How can I calculate the energy of a solution by knowing all of it's elements?
**For example:**
If I have 2 liters of salting water $\mathbf{NaCl_{(aq)}+H_2O_{(l)}}$ contains 1.5 g of salt, how can I determine the internal energy stored in it? |
My questions relates to the fundamental concept of electrochemistry, more specifically the electrode potentials.
**1)** First, why is there a potential difference at the interface of two phases? Considering the simplest case of a metal rod dipped in the solution of its ions, why should there be a potential diffe... |
I really don't know anything about chemistry, but I was wondering about the following vague question: has any substance been created that does not contain any metallic elements, but is metallic? In fact, the only nonelemental metals I know of are alloys, so I may as well ask whether we have ever created any metallic *... |
Have we ever created artificial metals? |
Why Add Salt to Vinegar to Clean Pennies? |
I am studying for a final tomorrow and I was going through some problems on older exams and came across one which I wasn't really sure how to solve. My boyfriend told me to look for this site because he uses stack overflow a lot to help people out with CS problems.
The problem is to write the balance equation wh... |
I am studying for a final tomorrow and I was going through some problems on older exams and came across one which I wasn't really sure how to solve. My boyfriend told me to look for this site because he uses stack overflow a lot to help people out with CS problems.
The problem is to write the balance equation wh... |
I am studying for a final tomorrow and I was going through some problems on older exams and came across one which I wasn't really sure how to solve.
The problem is to write the balance equation when:
managnese(IV)oxide is reduced to manganese(II) oxide by hydrogen gas.
I took a few approaches to this, beca... |
My friend once told me that technically , we should not draw Lewis dot structure of molecules containing no central atom.(eg.benzene,acetic acid) Is he right ? If yes, then what is the reason behind this ? |
When should we not draw a Lewis dot structure? |
Lets say you have the reaction
aA + bB => cC + dD
The rate of the reaction is given by the change in initial concentration over the change in time.
$-\frac{\Delta \left[ A \right]}{a\Delta T}\; =\; -\frac{\Delta \left[ B \right]}{b\Delta T}\; =\; \frac{\Delta \left[ \mbox{C} \right]}{c\Delta T}\; =\; \frac{\De... |
Difference between Reaction Rate and Rate Law? |
Lets say you have the reaction
$\ce{aA + bB -> cC + dD}$
The rate of the reaction is given by the change in initial concentration over the change in time.
$-\frac{\Delta \left[ A \right]}{a\Delta T}\; =\; -\frac{\Delta \left[ B \right]}{b\Delta T}\; =\; \frac{\Delta \left[ \mbox{C} \right]}{c\Delta T}\; =\; \f... |
A half-cell consisting of palladium rod dipping into a $1\ M$ $Pd(NO_3)_2$ solution is connected with a standard hydrogen half-cell. The cell voltage is $0.99\ volt$ and the platinum electrode in the hydrogen half-cell is the anode. Determine $E^ο$ for the reaction $Pd\longrightarrow Pd^{+2}+2e$.
Now the question is... |
[Wikipedia][1] says that esters can be reduced to aldehydes using DIBAl-H. Can anyone please explain how this reaction occurs?
[1]:http://en.wikipedia.org/wiki/Aldehydes#Specialty_methods |
How does partial reduction of esters to aldehydes occur? |
If I were to buy/build a large still, that was air tight, and could hold a vacuum, and filled the reservoir with vegetable glycerin (which has a boiling point higher than the majority or desired organic compounds) and I made the atmospheric pressure inside less than normal atmospheric pressure, could I distill chemic... |
I have to calculate the enthalpy of the reaction
$$\ce{Cs(l) + 1/2I2(s) -> CsI(s)}$$
and the answer is
$$\Delta H_f = \Delta H_{vap}^{\ce{Cs}} + \frac{1}{2}\Delta H_{subl}^{\ce{I2}} + \frac{1}{2}E_{diss}^{\ce{I2}} + I_1^{\ce{Cs}} + E_A^{\ce{I}} + E_N.$$
I can see that the molecules are first put to gas state before... |
Why do molecules have to first transform to gas before doing a reaction? |
If we change the null half-potential, would it change half-potentials of other half-cell reactions by the same amount, so that voltages of net reactions stay the same? |
I was wondering if anyone had any insight as to why the reaction of chlorosulfonic acid (colorless) and 1-dodecanol (colorless) produces a deep dark red colored solution? The reaction should give hydrogen lauryl sulfate, which according to [this website](http://www.guidechem.com/dictionary/151-41-7.html), is a white so... |
Wiki says:
[Oxidation state] is defined as the charge an atom might be imagined to have when electrons are counted according to an agreed-upon set of rules:
the oxidation state of a free element (uncombined element) is zero
for a simple (monoatomic) ion, the oxidation state is equal to the ne... |
How to determine an oxidation number of an atom in the compound, that has at least two elements, which are not hydrogen or oxygen? |
After 10 days of searching, I couldn't find a source about MS configurations. What I want to know is something like this:
If MALDI is used as an ionization method, then TOF as an analyzer is suitable since the MALDI creates singly charged ions which have high m/z ratio and only TOF can analyze that ions, and multich... |
I have to calculate the enthalpy of the reaction
$$\ce{Cs(l) + 1/2I2(s) -> CsI(s)}$$
and the answer is
$$\Delta H_f = \Delta H_{vap}^{\ce{Cs}} + \frac{1}{2}\Delta H_{subl}^{\ce{I2}} + \frac{1}{2}E_{diss}^{\ce{I2}} + I_1^{\ce{Cs}} + E_A^{\ce{I}} + E_N.$$
I can see that the molecules are first put to gas state before... |
If MALDI is used as an ionization method, then TOF as an analyzer is suitable since the MALDI creates singly charged ions which have high m/z ratio and only TOF can analyze that ions, and multichannel plate should be used because the TOF is very quick and MCP's duty time is enough to capture all ions.
Is there a kin... |
If MALDI is used as an ionization method, then TOF as an analyzer is suitable since the MALDI creates singly charged ions which have high m/z ratio and only TOF can analyze that ions, and multichannel plate should be used because the TOF is very quick and MCP's duty time is enough to capture all ions.
Is there a kin... |
When I have a Gadolinium ion (3+ => Gd3+), how can I calculate the electron configuration of it?
electron cfg (Gd) = [Xe]4f^7 5d^1 6s^2
Do I need to first subtract the 2 electrons in the s-orbital and then the (d/f)orbital? |
Gold and Chromium have weird electron configurations, because electrons are differently divided : eg an electron jumps from a s-orbital to a d-orbital to have a half-filled s orbital and a fully/half filled d-orbital, which is much more stable.
But does this also occur with the p-orbitals? eg why does Fluorine not tra... |
Special electron configurations in p block on periodic table? |
Was there any logic or thinking behind the experiments performed by Cannizzaro, Beckmann, Gattermann, Koch etc.? Whether they thoughtfully performed experiments or just added any two reactants and luckily discovered the reactions which are known by their name today.? I mean to ask that in Physics all problems are treat... |
Uranyl formate has a structure something like:
$UO_2-(OCHO)_2$
So the structural formulae I've seen have two double-bonded oxygens directly attached to the U and each formate group is attached by single bonds to the oxygens. Like <a href="http://images.chemnet.com/suppliers/chembase/cas3/cas16984-59-1.gif">this.<... |
If the fluorescence is the re-emitting of a photon with a larger wavelenght due to the transition from a higher energy state to a lower energy state the case of resonance Raman (where there aren't any virtual states) seems be equal to the fluorescence. Which differences are there? |
Which are the differences between resonance Raman and fluorescence? |
Building on @Philipp and @chipbuster's answers-
##What is Activity?
When we have dilute solutions or small quantities of a gas or other substance, the substance behaves as if the particles are just points, rather than having a size. In these settings we often use a simplified set of equations.
For example, wit... |
is there any difference between 18 electron rule and effective atomic number rule? both rules are based on Attainment of a noble gas configuraion as a criteria for stability of complexes.besides,both rules were proposed by sigwick.i was wondering if the mere fact that 18 electron rule applies mainly to organometallic c... |
Building on @Philipp and @chipbuster's answers-
##What is Activity?
When we have dilute solutions or small quantities of a gas or other substance, the substance behaves as if the particles are just points, rather than having a size. In these settings we often use a simplified set of equations.
For example, wit... |
Is there any difference between [18-electron rule][1] and [effective atomic number rule][2]? Both rules are based on attainment of a noble gas configuraion as a criteria for stability of complexes. Besides, both rules were proposed by Sidgwick. I was wondering if the mere fact that 18-electron rule applies mainly to or... |
Is there any difference between [18-electron rule][1] and [effective atomic number rule][2]? Both rules are based on attainment of a noble gas configuraion as a criteria for stability of complexes. Besides, both rules were proposed by Sidgwick. I was wondering if the mere fact that 18-electron rule applies mainly to or... |
For an ideal chain, Flory Huggins theory gives us a distribution which is like a Gaussian.
$$P(l, r) \sim \left(\frac{3}{2 \pi l^2}\right)^{3/2} e^{\frac{-3 r^2}{2 l^2}}$$
where, $l$ is the monomer to monomer distance(also known as Kuhn length) and $R$ is the size of the monomer
This is great but what are the ... |
I am having trouble understanding how valence electrons are counted in Helium.
My references are:
1. [Here][1] where it appears that Helium has 0 valence electrons because the shells are finished
2. [Here][2] where it appears that Helium has two valence electrons (which is what I thought)
How many valence ... |
Valence electrons in Helium? |
If we look at solubility of salts in water, we are told that they disassociate, because the positive $\ce{Na}$ ion is attracted to the partially negative oxygen in water and the negative $\ce{Cl}$ is attracted to the partially positive hydrogen. But why does this happen? I mean, the couloumb force should be much stron... |
Why do salts dissolve? Why do $\ce{NaCl}$ crystals not stick together? |
By chance, we received some monolayer [graphene][1] sheets (20 cm x 20 cm) and mixed coper-graphene wires for free at our university. I would like to prepare some very-easy-to-do experiments for the chemistry students that show the awesome properties of graphene, and which could be carried out with very simple lab equi... |
I was taking a chemistry test and I encountered the following question:
> How many electrons can an orbital of type f hold?
>
> A. 6
> B. 10
> C. 2
> D. 14
> E. 1
Since there can be [-ℓ, ℓ] orientations and since the orbital type f has ℓ = 3, we should have 7 possible orientations with 2 spins, so ... |
How many electrons can an orbital of type f hold? |
We all know that pure water can't conduct electricity. But during electrolysis, if add a small amount of HCL acid inside, water could be decomposed to hydrogen gas and oxygen gas, as it is reduced at the cathode and oxidised at the anode. So why can't pure water just conduct electricity by electrolysis? |
Why can't pure water conduct electricity since it can be reduced at cathode and oxidised at anode? |
Recently the [quack medicine](http://articles.mercola.com/sites/articles/archive/2013/08/18/exclusion-zone-water.aspx) folks online have been promoting the research of a certain [Dr. Gerald Pollack](http://faculty.washington.edu/ghp/) who claims to have discovered a "forth phase of water", and who has recently publishe... |
EZ-Water - Fraud or breakthrough? |
Looking at Wikipedia, Gold & Platinum are in adjacent seats.
Platinum Gold
[Xe] 4f14 5d9 6s1 [Xe] 4f14 5d10 6s1
Atomic number of 78 Atomic number of 79
Atomic pass of 195.084u Atomic mass of 196.96657 ± 0.0000... |
What makes Gold so different from Platinum? |
Copper have $[Ar] 3d^{10} 4s^1$ electron configuration. And Zinc have $[Ar] 3d^{10} 4s^2$ electron configuration.
My question is, what is the right quantum numbers of last electron of copper? Is it $$a. n=3,l=2,m=+1,s=-1/2$$ or $$b. n=3,l=2,m=+2,s=-1/2$$
If I use A, the electron configuration of copper is $[Ar] 3... |
What is the right quantum numbers of Copper? |
I was linked to a Kickstarter for a cooling ball to be placed in drinks which claims with constant marketing hyperbole how much it relies on "Phase Change" ! which is a neat concept and seems not unreasonable, but in thinking about it I'm failing to imagine (as I'm no chemist, and of ill education) what refrigerant cou... |
What non-toxic non-water substances have a freezing point very close to water's? |
I was taking a chemistry test and I encountered the following question:
> How many electrons can an orbital of type f hold?
>
> A. 6
> B. 10
> C. 2
> D. 14
> E. 1
Since there can be [-ℓ, ℓ] orientations and since the orbital type f has ℓ = 3, we should have 7 possible orientations with 2 spins, so ... |
I was linked to a Kickstarter for a cooling ball to be placed in drinks which claims with constant marketing hyperbole how much it relies on "Phase Change" ! which is a neat concept and seems not unreasonable, but in thinking about it I'm failing to imagine (as I'm no chemist, and of ill education) what refrigerant cou... |
If the fluorescence is the re-emitting of a photon with a larger wavelenght due to the transition from a higher energy state to a lower energy state the case of resonance Raman (where there aren't any virtual states involved) seems be equal to the fluorescence. Which differences are there? |
I'm not an expert.
In simple words how do they differ:
`H-H-O`
and
`H-O-H` molecules? |
I'm curious, I was trying to look into the affect of freezing a solution with water even when the solution is completely miscible. I came across something that detailed this regarding salt water and basically said when it gets low enough to freeze, the water forms it's tell-tale lattice basically pushing the salts out ... |
Does freezing a solution with water always cause the water to separate and form the ice lattice? |
I know the Cannizzaro reaction takes place in carboxyl compounds without $\alpha$-H with the regular examples being formaldehyde and benzaldehyde.
But can this reaction take place with say diphenylmethanone or di ter-butyl ketone(2,2,4,4-tetramethylpentan-3-one) or 2,2-dimethylpropanal ?
I couldn't find any exa... |
Can substituted acetone undergo Cannizzaro reaction? |
If a compound is placed before you and you are asked to determine what it is and what it's structure is,how do you actually do that ?
This might be a baby question for most of you but I am not from chemistry background and so this amazes me ! |
How do we actually know the chemical structure of a compound? |
I apologize for a perhaps newbie question. I would like to compute the potential energy surface for several small molecular ions, like H2+, H3+, using a quantum chemistry software. What are the proper method and basis set to do that and why? I am thinking about rohf/sto-3g or uhf. |
I must confess, I am not a chemistry student but have always been a fan of it, so I am not sure if this is a blunder.
I have often wondered if Thermoplastics can ever be converted to or made to behave like a Thermosetting plastic. In other words, can a Thermoplastics be made more heat resistant? |
Is Mn(C₂H₃O₂)₂ soluble in water? |
I apologize for a perhaps newbie question.
I would like to compute the potential energy surface for several small molecular ions, like $\ce{H2+}$ and $\ce{H3+}$, using quantum chemistry software. What are the proper method and basis set to do that and why? I am thinking about ROHF/STO-3G or UHF. |
I have this problem,
Liquid bromine is added to a container of sodium iodide crystals
I interpreted it with this molecular formula $Br_2(l) + 2NaI(s) \rightarrow 2NaBr(s) + I_2(g)$.
From my understanding, since none of the products nor any of the reactants is aqueous, there shouldn't be a net ionic equation. ... |
What is the net ionic equation for this molecular equation? |
Which computational method/basis set should I use for small molecular ions? |
Technically you are correct. How can there be any ions when the reactants are not in aqueous medium ? But here it is a matter of convention and maybe an illustration of how to write the ionic equations from molecular ones. Likewise, if you have done balancing of redox reactions , you might notice half of the reactions ... |
Let's assume a setup with a static linear molecule with three identical atoms connected by bonds and a single atom, identical to the other three, being shot at the molecule. Let's also assume that everything happens in 1D and can therefore be illustrated by this simple scheme:
(projectile) A -> A-A-A (molecul... |
We have seen that HBr shows Anti-Markovnikov effect when it reacts with alkenes ; in presence of peroxides. Why only HBr shows this effect ? Why don't other halides ? |
Why does sulfate have this structure? |
I'm curious, I was trying to look into the affect of freezing a solution with water even when the solution is completely miscible. I came across something that detailed this regarding salt water and basically said when it gets low enough to freeze, the water forms it's tell-tale lattice basically pushing the salts out ... |
Why does sulphate have this structure? |
Why does sulfate have this structure? |
The ration of the heat capacities Cp/Cv for one mole of a gas is 1.67. The gas is:
a)He
----------
b)H2
----------
c)CO2
----------
d)CH4
Is answer to this question based on finding the degrees of freedom and from that finding whether the gas is mono atomic,diatomic etc? If is on... |
Is chlorine in there that accumulates (at the anode) and emerge out as chlorine gas? I was worried since I added a pinch of salt to the steamer inorder to hasten the heating of tap water when I caught a cold (I should've just boiled a pot of water on the stove). I'm worried since chlorine gas is bad for the respiratory... |
The ratio of the heat capacities $\frac{C_p}{C_v}$ for one mole of a gas is 1.67. The gas is:
> a)He
>
> b)H2
>
> c)CO2
>
> d)CH4
I know how to answer this by analysing the degrees of freedom of the gas molecule. Is there any other way to derive the ratio? |
I'd go about such a question looking at the easiest thing first: ideal gases. So, what do you know about the relations between $C_{p}$ and $C_{v}$ (both being the molar heat capacities at constant pressure and constant volume, respectively) for ideal gases? For one thing, it is well known that
\begin{equation}
C_... |
I think an important point to mention here is that Lewis dot structures, and the octet rule, are simply *models that describe experimental observables.* For example, the concept of valency works well with organic molecules but was challenged by [Alfred Werner](http://en.wikipedia.org/wiki/Alfred_Werner) in the developm... |
What is the structure of the molecule N5P3?
N5P3 is not documented online so could anyone please say the structure of the molecule :
- How many ligands does each Phosphorous atom have?
- How many ligands does each Nitrogen atom have? |
Structure of N5P3? |
I guess that a long time ago there was a lot of H2S in the atmosphere and then the H2S could have reacted with that lead oxide to form PbS?
On wikipedia it says (under Lead(II)oxide,reactions) :
The red and yellow forms of this material are related by a small change in enthalpy:
PbO(red) → PbO(yellow... |
N₅P₃ is more commonly written as P₃N₅, and known as **[triphosphorus pentanitride](http://webbook.nist.gov/cgi/cbook.cgi?ID=C12136913)**. It's a **crystalline solid** at ambient conditions: it is **not a molecular compound**. From the [first publication that reported the pure compound and its structure](http://pubs.acs... |
What is the structure of the molecule N₅P₃?
N₅P₃ is not documented online so could anyone please say the structure of the molecule:
- How many ligands does each Phosphorous atom have?
- How many ligands does each Nitrogen atom have? |
Structure of N₅P₃? |
The reaction between p-methylbenzaldehyde and NaOH is an example of:
The question has choices for answers which include A) canizzaro reaction B) aldol condensation.
and two more.
I selected aldol condensation as the given compound is an aldeyde and it reacts with NaOH. But, the answer is given to be A). Why is ... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.