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The process of racemization of an optically compound is entropy driven and hence nature prefers a racemic mixture to an optically active one, which is consistent with the idea of the intuitive understanding of entropy as the degree of randomness or disorder. But then how can the entropy change of a process of conversio... |
Entropy and recemisation? |
The process of racemization of an optically compound is entropy driven and hence nature prefers a racemic mixture to an optically active one, which is consistent with the idea of the intuitive understanding of entropy as the degree of randomness or disorder. Then, how can the entropy change of a process of conversion o... |
Entropy and racemization? |
Why is methoxide strong base? In case of halogens, I get why one is weak base, and one is strong base, but in the case of ones with oxygen, this seems to be hard to figure out. |
I have searched the internet and I found that reusing PET no.1 is dangerous. Why it is dangerous and what is the equation of the reaction between it and water tap ? And why it is not danger to when it is used for the first time in water bottles but it is danger when reusing it ?
Thanks!
Links I have found useful:... |
For a titration, if you want to know the concentration of an acid you use a strong base such as NaOH. My question is; why you can't use a weak base for this purpose? Is it because the calculation would be tougher? Is it because you'd need more of the base? I'm at a loss. |
I have a can of spray for self-protection which has expired way back in 2008. It hasn't been used at all, and it doesn't seem a good idea to just throw it away without disabling it somehow first. I'm looking for ways to disarm it with minimum risk to myself and others. Obviously, I can just spray it away, but I'd rathe... |
How to disarm and correctly dispose of tear gas spray? |
Can a spark ignite hydrogen? Also, what about the tip of a cigarette? I've heard that hydrogen is very explosive. Thanks |
Can a spark ignite hydrogen? |
Some recent developments shown in article [Transversely quasicrystallographic 3D photonic chiral lattices: Polarization-controllable complex photonic band gap structures][1], where autors claimed experimantal results on produsing 3d chiral photonic quasicrystals.
![enter image description here][2]
"So the fabric... |
Some recent developments shown in article [Transversely quasicrystallographic 3D photonic chiral lattices: Polarization-controllable complex photonic band gap structures][1], where autors claimed experimantal results on produsing 3d chiral photonic quasicrystals.
![][2]
>*Figure. Computer simulation of the light... |
Some recent developments shown in article [Transversely quasicrystallographic 3D photonic chiral lattices: Polarization-controllable complex photonic band gap structures][1], where autors claimed experimantal results on produsing 3d chiral photonic quasicrystals.
![][2]
>*Figure. Computer simulation of the light... |
`Can a spark ignite hydrogen? Also, what about the tip of a cigarette?`
Yes, if the $\ce{H2(g)}$ concentration is greater than 4% not only will it burn, but most likely explode. You should avoid all heat sources when dealing with it, including direct sunlight. Just so you know, hydrogen safety datasheets include wor... |
Is water neutral in nature or amphoteric in nature? I understand it as an neutral compound in complex compounds, but I've been told that it is amphoteric, too. |
What is the nature of water? |
I have a bottle of baby powder that is 15% Zinc oxide and the rest is talc. Is there an over-the-counter way of purifying zinc oxide from it? I'm trying to make some sunscreen from it. |
This might be not worth it, because you will need special equipment.
Description totally theoretical.
Mixture consist of $Mg_3Si_4O_{10}(OH)_2$ - tale powder, $ZnO$ - zink oxide powder, and [starch][1]. 81% to 15% to 4% it's most common variation with 15% zink oxide, there also 10% mixtures, but process will be ... |
This might be not worth it, because you will need special equipment.
Description totally theoretical.
Mixture consist of $Mg_3Si_4O_{10}(OH)_2$ - tale powder, $ZnO$ - zink oxide powder, and [starch][1]. 81% to 15% to 4% it's most common variation with 15% zink oxide, there also 10% mixtures, but process will be ... |
This might be not worth it, because you will need special equipment.
Description totally theoretical.
Mixture consist of $Mg_3Si_4O_{10}(OH)_2$ - tale powder, $ZnO$ - zink oxide powder, and [starch][1]. 81% to 15% to 4% it's most common variation with 15% zink oxide, there also 10% mixtures, but process will be ... |
A few addition comments.
The production of water would create a problem, as if being used as a heat source, how is the water going to escape? Steam and condensation can cause many problems, not to mention; there is the issue of steam and the safety risk to end user. All these factors also cause metal pipes, machine... |
A few addition comments.
The production of water would create a problem, as if being used as a heat source, how is the water going to escape? Steam and condensation can cause many problems, not to mention; there is the issue of steam and the safety risk to end user. All these factors also cause metal pipes, machine... |
Are you sure you didn't mean the name of this molecule? Because strictly speaking, the molecular formula of the molecule you posted would be $\ce{C5H8}$. Pent-2-ene has molecular formula $\ce{C5H10}$.
The molecule you asked about has a triple bond, meaning that it's an **alkyne** and in this case, pent-2-yne. If you... |
What is the type of energy created by chemical reactions? Does it include subatomic particles, or is it devoid of physical form? Many chemical reactions such as combustion are said to produce energy as heat and light, but what does that technically mean on the subatomic scale? Thanks. |
What is the energy released in chemical reactions? |
So I was thinking about something to do for a science fair and photosynthesis sounded like a good idea. I was wondering what the exact process of photosynthesis was on a chemical level. I know the formula, but how exactly is water and carbon dioxide converted into glucose and oxygen? And where does sunlight come in,... |
In a battery what would happen if you had a perfectly uniform and pure cathode? |
I don't think that's accurate. Even the universe doesn't have an "unlimited supply of electrons".
Impurities in the cathode likely give rise to internal resistance inside the battery (among other things), leading to deviation from an ideal cell. I would guess that as your cathode approached purity, your battery woul... |
I have to determine the empirical formula of an oxide of iron which has 69.9% iron and 30.1% dioxygen by mass in it.
I have started as follows:
STEP 1: For our convenience we take 100g of that iron oxide,
so, we have 69.9g of iron in it and 30.1g dioxygen in it
STEP 2: we convert into number moles o... |
$\ce{NH4-}$ is conjugate acid and $\ce{NH4}$ is conjugate base. $\ce{NH4-}$ is conjugate acid because it has one more Hydrogen.
The thing that is difficult for me to understand is why $\ce{NH4-}$ is anion? Is negative sign refer to whole molecule or just to Hydrogen? How a molecule can be anions? |
Why $\ce{NH4-}$ is anion and $\ce{NH3}$ is not? |
$\ce{NH4-}$ is conjugate acid and $\ce{NH4}$ is conjugate base. $\ce{NH4-}$ is conjugate acid because it has one more Hydrogen.
The thing that is difficult for me to understand is why $\ce{NH4-}$ is anion? Is negative sign refer to whole molecule or just to Hydrogen? How a molecule can be anions?
Another example... |
When a chemical reaction such as combustion occurs, it is said to create energy. What is/are the forms of this energy? For example, is the energy made of electrons or other subatomic particles and actually dispersed? Is it all potential energy? What does it technically mean when energy is produced as a product of a... |
I was trying to make Calcium metal by electrolyzing molten CaCl2. I used a stainless steel spoon and a thick steel wire as electrodes. Then I attached them to a power supply. I placed some CaCl2 in the spoon and melted with a gas torch. I then placed the steel electrode in the molten pool and gradually pulled it out. A... |
I was trying to make Calcium metal by electrolyzing molten $CaCl_2$. I used a stainless steel spoon and a thick steel wire as electrodes. Then I attached them to a power supply. I placed some $CaCl_2$ in the spoon and melted with a gas torch. I then placed the steel electrode in the molten pool and gradually pulled it ... |
Related: http://chemistry.stackexchange.com/q/4315/1892
What is the half-life of hydrogen bonds in a glass of water at room temperature, say 18 degrees Celcius? I guess values may be different for distilled water and for tab water, but both may be intersting.
My attempts to get an answer involve searching with g... |
[This paper][1] provides a very good overview of the state of knowledge about the mechanism of water oxidation (which is pretty much the heart of artificial photosynthesis). So if you want to understand the process of oxygen formation from water on a molecular level this is a very good and fairly recent review of the f... |
When a chemical reaction such as combustion occurs, it is said to create energy. What is/are the forms of this energy?
For example, is the energy made of electrons or other subatomic particles and actually dispersed? Is it all potential energy? What does it technically mean when energy is produced as a product ... |
What is the most logical and easy to remember step-by-step method for drawing Lewis dot structures? I'm having trouble drawing a simple one for CO2.. |
How to draw Lewis dot structures? |
Let's start off on common footing by making sure we understand the definition of energy:
**Energy** is the capacity to do work.
An object may have many types of energy, we'll get to those in a second, but the *total energy* of an object will be the sum of its **kinetic energy** and its **potential energy**. Kine... |
What is the most logical and easy to remember step by step method for drawing Lewis dot structures?
I'm having trouble drawing a simple one for $CO_2$. |
Related: http://chemistry.stackexchange.com/q/4315/1892
What is the half-life of hydrogen bonds in a glass of water at room temperature, say 18 degrees Celsius? I guess values may be different for distilled water and for tab water, but both may be intersting.
My attempts to get an answer involve searching with g... |
I [have read][1] that it is possible to revive a dead Li-ion battery by putting it in the freezer for *three to seven days*, then letting it get back to room temperature. Can this process work, and if so, what is the reason behind it?
[1]: http://www.ehow.com/how_5982537_revive-lithium-ion-batteries.html |
Reviving Li-ion battery in freezer? |
I [have read][1] that it is possible to revive a dead Li-ion battery by putting it in the freezer for *three to seven days*, then letting it get back to room temperature. Can this process work, and if so, how does it work?
[1]: http://www.ehow.com/how_5982537_revive-lithium-ion-batteries.html |
In organic chemistry, people draw 2p orbitals like this:
![2p static][1]
and then they explain how the orbitals combine to non-bonding (π*) or bonding (π) molecular orbitals, like this:
![orbitals bonding][2]
depending on whether the orbitals overlap out-of-phase (blue + white) or in-phase (blue + blue, or ... |
I [have read][1] that it is possible to revive a dead Li-ion battery by putting it in the freezer for *three to seven days*, then letting it get back to room temperature. Can this process work, and if so, how does it work?
Somehow the opposite, i.e. heating (cooking) the battery, would be more intuitive to me. After... |
I [have read][1] that it is possible to revive a dead Li-ion battery by putting it in the freezer for *three to seven days*, then letting it get back to room temperature. Can this process work, and if so, how does it work?
Somehow the opposite, i.e. heating (cooking) the battery, is more intuitive to me. After all, ... |
I read this question : http://chemistry.stackexchange.com/questions/5202/flame-temperature-for-cooking-food and was thinking, could companies colour there flames so that products would heat quicker? how would they do this, also could you use this to make an infrared or ultraviolet flame? if you could how hot would they... |
Can you colour a flame, and what would the effects be? |
I was learning about voltaic cells and came across salt bridges. If the purpose of salt bridge is only to move electrons from electrolyte solution to the other, then why can I not use a wire?
Also, will using $NaCl$ instead of $KNO_3$ in making of salt bridge have any effects on voltage/current output of the cell? w... |
Why is it important to use a salt bridge in a voltaic cell? can a wire be used? |
Most people that have ever visited a viticulteur (winemaker) will know that it is common wisdom that vibrations are bad for the wine quality. When I was just a kid the winemaker always told me that we should be silent because the wines needed to sleep, but later a different one explained that this must have been to sto... |
I [have read][1] that it is possible to revive a dead Li-ion battery by putting it in the freezer for *three to seven days*, then letting it get back to room temperature. Can this process work, and if so, how does it work?
Somehow the opposite, i.e. heating (cooking) the battery, is more intuitive to me. After all, ... |
The purpose of a salt bridge is **not** to move electrons from the electrolyte, rather to maintain charge balance because the electrons are moving from one half cell to the other.
Regarding the second part of your question, it is important to use a salt with inert ions in your salt bridge. In your case, you probabl... |
This question is probably a [duplicate](http://chemistry.stackexchange.com/questions/5477/) and [there's another question](http://chemistry.stackexchange.com/questions/2644) related to salt bridges on this site.
The purpose of a salt bridge is **not** to move electrons from the electrolyte, rather to maintain charge... |
How is it determined how many electrons are transferred in redox reactions? |
Apart from hydrogen which forms a duet, which element's don't observe the octet rule? |
What elements don't observe the octet rule? |
What does it mean to shift equilibrium? For example, the equilibrium shifts to the left...don't understand that.. |
What does it mean to shift equilibrium? |
Probably you are having problems with Le Chatlier's Priciple.
Suppose you have an equilibrium established between four substances A, B, C and D.
<br>
`What would happen if you changed the conditions by increasing the concentration of A?`
<br>
According to Le Chatelier, the position of equilibrium will move in su... |
How does he effect of heat and effect of substituents affect racemization of biphenyl compounds? |
I [have read][1] that it is possible to revive a dead Li-ion battery by putting it in the freezer for *three to seven days*, then letting it get back to room temperature.
*Can this process work, and if so, how does it work?*
Notes:
* Somehow the opposite, i.e. heating (cooking) the battery, is more intuitive... |
I have got around to at least read on Wikipedia, and it does not clarify how this works in any sensible manner.
I wondered how the chemicals make electrons "move". How is the basic understanding of this? |
How do the stored chemicals in batteries drive electronic current from their terminal to outside devices? |
I boiled a solution of glycerol and water at about 160 degree Celsius and got a brown liquid much less in volume (boiled off the entire water i think; also not so sure about the accurate temperature). Before mixing glycerol with water it was a colourless liquid, now it is golden brown! why would that be? Also, I smelle... |
Probably you are having problems with Le Chatelier's Principle.
Suppose you have an equilibrium established between four substances A, B, C and D.
<br>
`What would happen if you changed the conditions by increasing the concentration of A?`
<br>
According to Le Chatelier, the position of equilibrium will move in ... |
Say we have the following reversible reaction: NaOH(s) <=> Na+(aq) + OH(aq) + 10.6 kcal
If we add OH- and equilibrium shifts to the left, does that affect the amount of NaOH(s) present or does it remain constant?
I'm confused because I remember that pure solids and liquids don't affect equilibrium value, or does... |
How do equilibrium shifts affect solids? |
I boiled a solution of glycerol and water at about 160 degree Celsius and got a brown liquid much less in volume (boiled off the entire water I think; also not so sure about the accurate temperature).
Before mixing glycerol with water it was a colourless liquid, now it is golden brown! Why would that be? Also, I sm... |
What is this brown liquid that I got when I boiled glycerol and water solution? |
I'm not satisfied with the rationale for the intermolecular attraction known as hydrogen bonding. In my book, it states that
> Hydrogen bonding is a special type of intermolecular attraction between the hydrogen atom in a polar bond (particularly H ¬ F, H ¬ O, and H ¬ N) and non-bonding electron pair on a nearby sm... |
What exactly is Hydrogen bonding (and why can't it exist with atoms other than Fluorine, Oxygen, Nitrogen)? |
How does the effect of heat and effect of substituents affect racemization of biphenyl compounds?
|
After cementing a wall, water is applied on the surface to keep it moist for strength for the next few days. I am unable to understand how this phenomenon is necessary for the strength of the concrete ? |
I [have read][1] that it is possible to revive a dead Li-ion battery by putting it in the freezer for *three to seven days*, then letting it get back to room temperature.
*Can this process work, and if so, how does it work?*
Notes:
* Somehow the opposite, i.e. heating (cooking) the battery, is more intuitive... |
Does the electronegativity only qualitatively describe bond polarity, or does it have any quantitative use? Is it possible to describe electronegativity in terms of other periodic properties, like valence electrons, $Z_{eff}$, etc. (thus eliminating the need of a separately defined value)? |
Is the electronegativity value ever used in calculations, or is it just a number assigned to each element? |
How are large quantities of the substances we use in the lab generally produced? (As in the process from getting the stuff out of the ground to use in the lab) How 'pure' are they? Also: is it possible to create relatively pure substances with household goods? |
How are pure substances (elements, compounds, etc) produced? |
Say we have the following reversible reaction: $NaOH_{(s) }$<=> $Na^+_{(aq) }$+ $OH^-_{(aq)}$ + 10.6 kcal
If we add $OH^-$ and equilibrium shifts to the left, does that affect the amount of $NaOH_{(s)}$ present or does it remain constant?
I'm confused because I remember that pure solids and liquids don't affect ... |
Say we have the following reversible reaction: $\ce{NaOH_{(s) }<=> Na^+_{(aq) }$+ $OH^{-}_{(aq)}}$ + 10.6 kcal
If we add $\ce{OH^-}$ and equilibrium shifts to the left, does that affect the amount of $\ce{NaOH_{(s)}}$ present or does it remain constant?
I'm confused because I remember that pure solids and liquid... |
Hydrogen has only one electron, yet the line spectrum of hydrogen has multiple lines. Why is this? |
Ca has an atomic radius of 197 pm and an electronegativity of 1
Mg has an atomic radius of 160 pm and an electronegativity of 1.31
Since Mg is smaller and has a higher electronegativity, one would think Mg would have a smaller hydrated radius than Ca, but it doesn't. Would someone explain to me why this isn't so... |
How could one determine the likelihood of one cation displacing another on a negatively charged exchange site of a clay particle?
For example, in a soil solution containing equal parts (by number of atoms) Ca++, Mg++, K+, Na+, Al+++, which cations will find the most exchange sites and which will ultimately be washed... |
I don't understand why liquids and solids have constant concentrations. Can anyone explain this to be in simple terms? |
Why do liquids and solids have constant concentrations? |
No lab reagent is 100% pure. But you can get [really close](http://www.sigmaaldrich.com/catalog/product/aldrich/339741) to that.
`How 'pure' are they?`
Read the label or do the analysis. It varies A LOT from one reagent to another.
`Is it possible to create relatively pure substances with household goods?`
... |
> How are large quantities of the substances we use in the lab generally produced?
use the wiki and the google, you ... lazy one. [here][1]
> Also: is it possible to create relatively pure substances with household goods?
Depends. Recrystallization can be performed at kitchen, so some substances can be purif... |
> How are large quantities of the substances we use in the lab generally produced?
use the wiki and the google, you ... lazy one. [here][1]
> Also: is it possible to create relatively pure substances with household goods?
Depends. Recrystallization can be performed at kitchen, so some substances can be purif... |
> How are large quantities of the substances we use in the lab generally produced?
[This is answered reasonable well on Wikipedia][1]
> Also: is it possible to create relatively pure substances with household goods?
Depends. Recrystallization can be performed at kitchen, so some substances can be purified at... |
I diluted sulfuric acid in deionized water in order to get a 10% H2SO4 solution.
I was going to use this solution as a cathode of a porous sample to measure its electrical properties.
However, this solution has a quite high resistivity (~200 ohm.cm DC).
I checked several sources that tell me that I should be m... |
Several organic compounds have resonance structures, but can a polymer have resonance structures? |
Can a polymer have different resonance structures? |
For use in a novel, I'd like to "construct" a clockwork device featuring phosphorus which could reasonably be expected to:
A) glow consistently.
B) explode upon some trigger (e.g., influx of air, mixture with another chemical, even a spark – that's what the clockwork is for), with enough explosive force or incend... |
What chemical available in 18th century would explosively react with phosphorus? |
Okay, so I was fiddling about in the chemistry lab, and I added:
Sodium Nitroprusside (soln) $Na_2[Fe(CN)_5NO]$ with Potassium Ferrocyanide (soln) $K_4[Fe(CN)_6]$.
$Na_2[Fe(CN)_5NO]$ was a yellowish-reddish colour - actually don't remember the _exact_ colour, while $K_4[Fe(CN)_6]$ was pale yellow.
Nothing rea... |
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