instruction stringlengths 15 21.8k |
|---|
Helium is the only element which does not freeze at atmospheric pressure, and only forms a liquid at around 4 Kelvin due to weak van der Waals forces.
I'm interested in knowing roughly how much hybridization/bonding occurs in liquid helium (for example, hybridization energy in cm$^{-1}$ or electronvolts). I would gu... |
More recent science (as compared to 1975), the action of Al with NaOH is believed to produce surface absorbed hydrogen atoms on the aluminum. Related chemistry is commonly employed via the vigorous action of HCl on Zn (so one of the roles of zinc is to provide added surface area, which may be acted upon by NaOH also, t... |
I am asked this chemistry question in my textbook:
>Write an ionic equation for this reaction:
$\ce{Mg(s) + H2SO4(aq) \implies MgSO4(aq) + H2(g)}$
This is my thought process and answer:
>1. $\ce{Mg(s) + H2SO4(aq) \implies MgSO4(aq) + H2(g)}$
2. $\ce{Mg(s) + H2+(aq) + SO4 2-(aq) \implies Mg 2+(aq) + SO4 2-(aq) ... |
Why did they ‘split’ this H2+ ion in the ionic equation? |
You are essentially correct, but the distinction is the degree of bonding.
As you described, in a polarized or partially ionic bond, the atomic orbital of the more electronegative atom is lower in energy. Thus, the bonding molecular orbital is closer in energy to that atomic orbital, and the antibonding molecular ... |
How are the pKa's of very strong acids derived mathematically? |
Are there any common (preferably somewhat complex) organic molecules that help combat ocean pollution? |
>Experimentally it was determined that extent of gas adsorption varies directly with pressure, and then it directly varies with pressure raised to the power 1/n until saturation pressure Ps is reached. Beyond that point, the rate of adsorption saturates even after applying higher pressure. Thus, the Freundlich adsorpti... |
$$\ce{Fe2O3 + 6HI -> 2FeI2 + I2 + 3H2O}$$
Why don't we get $\ce{FeI3}$? After all, iron's oxidation state is $+3$ in the reagent.
Should one just memorize that up to bromine, it's $\ce{FeX3}$, and below it's $\ce{FeX2}$? |
Why doesn't iron(III) iodide exist? |
I am asked this chemistry question in my textbook:
>Write an ionic equation for this reaction:
$\ce{Mg(s) + H2SO4(aq) \implies MgSO4(aq) + H2(g)}$
This is my thought process and answer:
>1. $\ce{Mg(s) + H2SO4(aq) \implies MgSO4(aq) + H2(g)}$
2. $\ce{Mg(s) + H2+(aq) + SO4^{2-}(aq) \implies Mg^{2+}(aq) + SO4 ^{2... |
When acrolein is heated with hydrazine we get dihydropyrazole. But I can't see how. First I think hydrazine should add on acrolein to form corresponding hydrazone, but what will happen next? Also is my first step correct? |
**tldr - atomic partial charges can be non-intuitive**
Formal charges in a Lewis structure don't always match up with partial charge assignment methods.
Typically, one wants 'accurate' partial charge models, for some definition of 'accurate' - but what that means can vary considerably. I explained some of this in... |
Why is Methanol more acidic than Ethanol eventhough the conjugate base of Ethanol is stabilised by hyperconjugation? |
In adjusting the **osmolarity** of a solution of *Benzalknonium Cl, Disodium Editate, and Disodium borate/boric acid buffer* to be isotonic (**about 290 mOsm**), the addition of NaCl showed unexpected behavior, possibly non-linear.
I strongly suggest that the **common ion effect** plays a role here, but how to acco... |
How to account for the common ion effect on osmolarity quantitatively? |
Helium is the only element which does not freeze at atmospheric pressure, and only forms a liquid at around 4 Kelvin due to weak van der Waals forces.
I'm interested in knowing roughly how much hybridization/bonding occurs in liquid helium (for example, hybridization energy in cm$^{-1}$ or electronvolts). I would gu... |
Suppose I have a beaker containing CuSO4 solution and I dip Cu rod in it.Now my question is what reactions are going to take place?Is the Cu rod going to acquire any positive charge?I am asking this question to clear my doubt regarding a daniell cell as to why Cu rod used in the cell should be positively charged.I don... |
I am not talking about zero-point energy.
I wish to understand how the energy of a system is calculated relative to a zero baseline. This is best explained with an example.
From DFT, the energy could be:
Isolated H = -13.6 eV,
H2 = -31.8 eV
What are these numbers related to? What would be a system... |
In adjusting the **osmolarity** of a solution of *Benzalknonium Cl, Disodium Editate, and Disodium borate/boric acid buffer* to be isotonic (**about 290 mOsm**), the addition of NaCl showed unexpected behavior, possibly non-linear.
I strongly suggest that the **common ion effect** plays a role here, but how to acco... |
I am asked this chemistry question in my textbook:
> Write an ionic equation for this reaction:
$$\ce{Mg(s) + H2SO4(aq) -> MgSO4(aq) + H2(g)}$$
This is my thought process and answer:
$\require{cancel}$
\begin{align}
\ce{Mg(s) + H2SO4(aq) &-> MgSO4(aq) + H2(g)}\\
\ce{Mg(s) + H2+(aq) + SO4^{2-}(aq)
&... |
How can we confirm or have a clear idea whether hydrogen bonding is taking place in substituents of cyclic compounds? For example, it takes place in ortho-nitrophenol, but it doesn't take place in ortho-flurophenol despite the fact that the nitro group and the fluorine are present at the same position and both are high... |
How to check whether intramolecular hydrogen bonding takes place in cyclic compounds? |
I am calculating the energy and charge transfer of a globally neutral system, composed by two opposely charged monomers (EMIM-BF4), coming closer to each other, with DFT (B3LYP) and MP2.
As a thumb rule, the larger the basis set, the better the energy result should be (given BSSE is taken in account). Is this also v... |
What is the effect of basis set on charge transfer? |
In the Wikipedia article on [crystallographic defects][1], a type of **point defect** known as an **interstitial defect** is described as follows:
> Interstitial defects are atoms that occupy a site in the crystal structure at which there is usually not an atom. They are generally high energy configurations. Small a... |
Interstitial defects in crystals: "high energy configurations"? |
I am calculating the energy and (Mulliken) charge transfer of a globally neutral system, composed by two opposely charged monomers (EMIM-BF4), coming closer to each other.
I am using localized basis set (BS) with DFT/B3LYP and MP2 (GAMESS US).
As a thumb rule, the larger the BS, the better the energy result should ... |
When I obtained the activation energy using the Arrhenius equation for a 10-minute glowstick (rapid, rigorous reaction), it was almost 4 times that of a 12-hour glowstick (slow, mild reaction).
However, I learned in chemistry that a reaction with a lower activation energy need less energy for successful collisions,... |
Is the activation energy always inversely proportional to the reaction rate? |
From a structure diagram alone it is hard to determine these interactions. The reason for this is that important structural parameters are stretched or shortened in order to flatten the molecule for a 2D drawing.
In a first order approximation a [molecular modelling kit based on balls and sticks](https://en.wikipedi... |
Why does water vapour deviate much more from ideal gas behaviour as it is cooled compared to nitrogen gas? |
How do you determine whether is it [products] - [reactants] or [reactants] - [products] when calculating the enthalpy change of a reaction? |
Is it more energy efficient to desalinate seawater by flash boiling or by flash freezing? |
Is this correct way to explain principle of RP-HPLC ?
"It works on the principle of hydrophobic interactions hence the more nonpolar the material is, the longer it will be retained." ? |
Is the following statement the correct way to explain principle of RP-HPLC?
> It works on the principle of hydrophobic interactions hence the more nonpolar the material is, the longer it will be retained. |
I'm in introductory chem, so I don't have much of the physical background to really understand what's going on yet, but we're learning about rotational energy levels, and how some rotational energy levels for molecules are degenerate.
As I understand it, degenerate energy levels correspond to different "ways in whi... |
What are Degenerate Rotational Energy Levels Physically? |
I have to sample 10mL of liquid hundreds of times a day at work.
We use a 10mL syringe to do so, but it takes a lot of time as they often allow more than 10mL to be drawn in (i.e. rather than a blind action, we have to check the measurement increments to make sure it’s exactly 10mL).
Is there a type of syringe of... |
If you need to measure $\pu{10.0\pm0.1 mL}$ repititively, then you can use a any available Bottletop Dispensers. For example, check [this](https://www.fishersci.com/shop/products/fisherbrand-autoclavable-bottletop-dispensers-6/p-4753023) and [this](https://www.grainger.com/product/46Z314?gclid=EAIaIQobChMI29ar46mJ5wIVg... |
If you need to measure $\pu{10.0\pm0.1 mL}$ repititively, then you can use an any available Bottletop Dispensers. For example, check [this](https://www.fishersci.com/shop/products/fisherbrand-autoclavable-bottletop-dispensers-6/p-4753023) and [this](https://www.grainger.com/product/46Z314?gclid=EAIaIQobChMI29ar46mJ5wIV... |
The electron configuration of a Silicon atom in its ground state is $\ce{1s^2 2s^2 2p^2 3s^2 3p^2}$, or equivalently, $\ce{[Ne] 3s^2 3p^2}$.
When looking at the energy-level scheme of a silicon atom, the valence electrons are distributed over two separate energy levels; specifically, the $\ce{3s}$ and $\ce{3p}$ ener... |
I have to sample $\pu{10mL}$ of liquid hundreds of times a day at work.
We use a $\pu{10mL}$ syringe to do so, but it takes a lot of time as they often allow more than $\pu{10mL} to be drawn in (*i.e.* rather than a blind action, we have to check the measurement increments to make sure it’s exactly $\pu{10mL}$).
... |
I have to sample $\pu{10mL}$ of liquid hundreds of times a day at work.
We use a $\pu{10mL}$ syringe to do so, but it takes a lot of time as they often allow more than $\pu{10mL}$ to be drawn in (*i.e.* rather than a blind action, we have to check the measurement increments to make sure it’s exactly $\pu{10mL}$).
... |
The Joint Entrance Examination board should update their outdated set of questions relying on rote memorization. Why do they assume the student has to memorize the charge of the ferric hydroxide particles and in what medium? Charge on the colloids is dependent on the medium and pH! They should also mention that the mol... |
> I have two questions...
>
> Why does a molecule "gain potential energy" when it rotates? Does it
> want to stop rotating for some reason?
>
> What do degenerate energy levels correspond to physically in terms of
> the molecule's rotation?
Do you remember the Newton's law of motion? A body in motion will ... |
There's a general principle here that applies anytime you calculate a change in a property:
The change in the value of a property in going from an initial state to a final state is always value(final state) - value(initial state).
For instance, what is the change in elevation (which we'll call height, h; not to be ... |
There's a general principle here that applies anytime you calculate a change in a property:
The change in the value of a property in going from an initial state to a final state is always value(final state) - value(initial state).
For instance, what is the change in elevation (which we'll call height, h; not to be ... |
There's a general principle that applies anytime you calculate a change in a property:
The change in the value of a property in going from an initial state to a final state is always value(final state) - value(initial state).
For instance, what is the change in elevation (which we'll call height, h; not to be confu... |
I am calculating the energy and charge transfer of a globally neutral system, composed by two opposely charged monomers (EMIM-BF4), coming closer to each other, with DFT (B3LYP) and MP2.
As a thumb rule, the larger the basis set, the better the energy result should be (given BSSE is taken in account). Is this also v... |
The wikipedia page states clearly that the coloured form of phenolphthalein is the one with two protons removed. What is the evidence that phenolphthalein loses both protons in basic solution? And does the only once deprotonated form ever appear? |
There is a formation of silver mirror in the silver mirror test. why does the silver does not precipitate, it forms the mirror in the silver mirror test? Is there any test that copper can form mirror? Why silver can form silver mirror but copper cannot? |
A copper mirror can be formed, for example [by reaction between $\ce{Cu(NH3)4^{2+}}$ and hydrazine in basic solution](https://books.google.com/books?id=btNF9aLXtPcC&pg=PA226&lpg=PA226&dq=copper+mirror+formation&source=bl&ots=HlrbSte45i&sig=ACfU3U0BTUadWnOEWwYhbP1Q3yZMz2DO_A&hl=en&sa=X&ved=2ahUKEwjY0p3G4YrnAhWSGM0KHfleB... |
Helium is the only element which does not freeze at atmospheric pressure, and only forms a liquid at around 4 Kelvin due to weak van der Waals forces.
I'm interested in knowing roughly how much hybridization/bonding occurs in liquid helium (e.g., energies in cm$^{-1}$ or electronvolts) at *ambient pressure and cryog... |
Disclaimer: This question comes from a physics student.
I was studying electrostatics and I was wondering how to charge a conductor at home without any fancy furs etc. So an idea came to me: take a battery, touch for example the negative terminal with the conductor and then remove it. Since the negative battery term... |
Is anode actually ever negative? |
Dewar benzene according to [Wikipedia](https://en.wikipedia.org/wiki/Dewar_benzene) has the IUPAC name **bicyclo[2.2.0]hexa-2,5-diene**.
Is it correct to give this name because resonance takes place and if we fix a certain numbering, as resonance takes place, a different carbon would occupy that numbering in a cycli... |
The Wikipedia article has a nice picture of the stages of deprotonation of phenolphthalein:
https://en.wikipedia.org/wiki/Phenolphthalein
[![enter image description here][1]][1]
However, there is a big jump here between H2In and In2-. In fact, smaller steps, showing just one deprotonation, are very reasonable.... |
o-nitrophenol is less acidic in comparison to p-nitrophenol due to intramolecular hydrogen bonding. This effect also is the reason for o-nitrophenol being less soluble in water.
At the same time, hydroquinone (para) is less acidic than catechol (ortho).
Of course there is the inductive effect, but a reason mention... |
as a PhD in chemistry and a chemistry teacher in university, I would like to see how you explain this utopical reason which pushes you to say if they were equally strong, 1M S2- should give only 0,5M OH- ?
S2- is in fact, stronger base than OH-, but weaker base than O2-.
S2- removes 1 H+ from H2O and forms HS- a... |
> Its given in my text book that colloidal dispersions of starch,rubber,proteins etc are lyophilic colloids whereas colloidal dispersions of metals,sulphides etc are lyophobic in nature.
But even the protein molecules have both hydrophilic as well as hydrophobic ends. And metals being ionised have strong affinit... |
What is the logic behind the terminology lyophilic and lyophobic colloids? |
For a chemical reaction in which some stoichiometric quantity of arbitrary chemical "A" decomposes into products "B" and "C",
aA --> bB + cC
or more simply:
aA --> Products
The depletion of substrate A at a concentration [A] can be modeled:
d[A] / dt = -k[A]<sup>n</sup>
If this is a first order re... |
For a 1st order reaction, how do you derive the integrated rate law for a product versus time? |
My textbook, *Solid-State Physics, Fluidics, and Analytical Techniques in Micro- and Nanotechnology*, by Madou, says the following:
> X-ray analysis reveals the symmetries of crystals (lattice type), distances between atomic planes (lattice parameter), the positions of atoms in crystals, the types of atoms from the... |
Do we really have technology with the resolution to distinguish between layers of single atoms of materials? |
In adjusting the **osmolarity** of a solution of *Benzalknonium Cl, Disodium Editate, and Disodium borate/boric acid buffer* to be isotonic (**about 290 mOsm**), the addition of NaCl showed unexpected behavior, possibly non-linear.
I strongly suggest that the **common ion effect** plays a role here, but how to acco... |
Its given in my text book that-
>Colloidal dispersions of starch,rubber,proteins etc are lyophilic colloids whereas colloidal dispersions of metals,sulphides etc are lyophobic in nature.
But even the protein molecules have both hydrophilic as well as hydrophobic ends. And metals being ionised have strong affinit... |
*o*-Nitrophenol is less acidic in comparison to *p*-nitrophenol due to intramolecular hydrogen bonding. This effect also is the reason for *o*-nitrophenol being less soluble in water.
At the same time, hydroquinone (*para*) is less acidic than catechol (*ortho*).
Of course there is the inductive effect, but a reas... |
In there an indicator for sulfur compounds like H2S (also organic)?
Or some straight forward way to measure if the H2S concentration in the air is higher than usual? Or is the concentration too low anyway? |
When H2SO4 is dissolved in water in little amounts (<1M), the pH scale can be used to measure the acidity of the solution. However, in larger concentrations, this breaks down and we have to use the Hammett acidity instead.
I have found this thesis (https://macsphere.mcmaster.ca/bitstream/11375/19972/1/Peel_Terence_E... |
Reference for Hammett acidities of dilute H2SO4? |
When H2SO4 is dissolved in water in little amounts ($<\pu{1M}$), the $\mathrm{pH}$ scale can be used to measure the acidity of the solution. However, in larger concentrations, this breaks down and we have to use the Hammett acidity instead.
I have found [this thesis](https://macsphere.mcmaster.ca/bitstream/11375/199... |
When $\ce{H2SO4}$ is dissolved in water in little amounts ($<\pu{1M}$), the $\mathrm{pH}$ scale can be used to measure the acidity of the solution. However, in larger concentrations, this breaks down and we have to use the Hammett acidity instead.
I have found [this thesis](https://macsphere.mcmaster.ca/bitstream/11... |
>Question
>It is an experimental fact that the pH of 1 M Na2S
is essentially the same as the pH of 1 M NaOH. Based on this information, is S2− or HO− the stronger Bronsted-Lowry base? How can you tell?
**Assumptions**
Questions asked as part of a course usually lack context for people not taking the course. T... |
After the formation of carbocation I was confused why would the reaction not go in favor of forming bornylene ,I am still not sure why but I think that sp2 hybridized carbon will cause a lot of strain in the ring.Another thing confuses me ,why does m... |
Why does methyl not shift in the mechanism of isoborneol to camphene? |
the system is a constant temperature and pressure throughout the process, only volume work is possible and it is in thermal equilibrium with the surrounding. Is that right? Are there any other constraints? |
What are the assumption of gibbs free energy equation referring to the system amd the surrounding? |
After the formation of carbocation, I was confused why would the reaction not go in favor of forming bornylene. I am still not sure why but I think that $\mathrm{sp^2}$ hybridized carbon will cause a lot of strain in the ring. Another t... |
the system for
$dG=dH-TdS$
is a constant temperature and pressure throughout the process, only volume work is possible and it is in thermal equilibrium with the surrounding. Is that right? Are there any other constraints? |
The system for
$\mathrm dG=\mathrm dH-T\,\mathrm dS$
is a constant temperature and pressure throughout the process, only volume work is possible and it is in thermal equilibrium with the surrounding. Is that right? Are there any other constraints? |
What are the assumption of Gibbs free energy equation referring to the system amd the surrounding? |
For a chemical reaction in which some stoichiometric quantity of arbitrary chemical $A$ decomposes into products $B$ and $C$,
$$a \ce{A} \ce{->} b \ce{B} + c \ce{C}$$
or more simply:
$$a\ce{A} \ce{->} \text{Products}$$
The depletion of substrate A at a concentration [A] can be modeled:
$$\frac{{\rm d}... |
Does ice increase the humidity of its surroundings? I'm trying to use the BME280 for an Arduino project regarding locating ice, but idk whether the atmosphere is more humid around ice. I'm trying to see whether humidity increases near ice. |
Does ice increase the humidity of its surroundings? |
What are the assumption of Gibbs free energy equation referring to the system and the surrounding? |
Why n-Butane has high B. p than iso-Pentane although both have equal no. of carbon atoms along the chain length? |
This is a class of carbocation 1,2-rearrangement reactions, and historically named [Wagner–Meerwein rearrangement](https://en.wikipedia.org/wiki/Wagner%E2%80%93Meerwein_rearrangement) after two chemists who discovered the reaction (see following diagram):
[![Classical & Nonclassical Carbocations][1]][1]
Although ... |
The only restriction on your equation is constant temperature. The system can be open or closed, the pressure does not have to be constant, and any type of work is allowed.
Let's start with the basic definition of G in terms of H, which is completely unrestricted:
$$G \equiv H-TS \Rightarrow dG = dH - d(TS) = dH... |
The only restriction on your equation is constant temperature. The system can be open or closed, the pressure does not have to be constant, and any type of work is allowed.
Let's start with the basic definition of G in terms of H, which is completely unrestricted:
$$G \equiv H-TS \Rightarrow dG = dH - d(TS) = dH... |
Is the following statement the correct way to explain principle of RP-HPLC?
> It works on the principle of hydrophobic interactions hence the more nonpolar the material is, the longer it will be retained. |
What is the principle of RP-HPLC? |
The only restriction on your equation is constant temperature. The system can be open or closed, the pressure does not have to be constant, and any type of work is allowed.
Let's start with the basic definition of G in terms of H, which is completely unrestricted:
$$G \equiv H-TS \Rightarrow dG = dH - d(TS) = dH... |
[![nic][1]][1]
[1]: https://i.stack.imgur.com/RPWhl.jpg
In this reaction, I don't know how I could place a methyl in the benzyl carbon. My first idea was to treat the compound with OsO4/H2O2 to form the vicinal diol, and then dehydrate in acidic medium and heat, but in this way I assume that carbocation is fo... |
Yes, interstitial defects increase potential energy, as [stated in your Wikipedia][1]: "In interstitial defects three or more atoms may share one lattice site, thereby increasing its total energy."
How can they form? One example is during rapid crystallization, where there is insufficient time for atoms to segregate... |
The only restriction on your equation is constant temperature. The system can be open or closed, the pressure does not have to be constant, and any type of work is allowed.
Let's start with the basic definition of G in terms of H, which is completely unrestricted:
$$G \equiv H-TS \Rightarrow dG = dH - d(TS) = dH... |
Yes, interstitial defects increase potential energy, as [stated in Wikipedia][1]: "In interstitial defects three or more atoms may share one lattice site, thereby increasing its total energy." See [Physics on StackExchange][6] for an explanation of potential energy in crystals.
How can they form? One example is du... |
Yes, interstitial defects increase potential energy, as [stated in Wikipedia][1]: "In interstitial defects three or more atoms may share one lattice site, thereby increasing its total energy." See [Physics on StackExchange][6] for an explanation of potential energy in crystals.
How can they form? One example is du... |
The only restriction on your equation is constant temperature. The system can be open or closed, the pressure does not have to be constant, and any type of work is allowed.
Let's start with the basic definition of G in terms of H, which is completely unrestricted:
$$G \equiv H-TS \Rightarrow dG = dH - d(TS) = dH... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.