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Most solids objects turn black after they are burnt.
But some turn white.
Why is that ? |
In the old days computer monitors and televisions were built from [cathode ray tubes][1] (CRTs) where the image was generated by an electron beam hitting phosphors which emitted light approximating the three primary colours.
What were the phosphors made from and what were the key reasons why the particular substanc... |
What chemical compounds were used in CRT phosphors? |
I seek to put a layer of fluorine on a rotationally molded cross-linked polyethylene (XPE) plastic gasoline tank. I sell tanks and they will be more eco-friendly if I can accomplish this.
I am an electrical engineer and my last experience with chemistry was [Chem 200 lecture and lab at SDSU][1], a one semester inte... |
Are there any compounds that reduce water's sensitivity to extreme heat change and/or volatility to high heat (over 800 degrees Fahrenheit), whether organic or inorganic? |
This may not be a proper chemistry question - I am in the process of constructing a kitchen waste digester (vegetable/fruits) from which, hopefully, over time adequate methane may be collected to burn. The digester won't be complete for several months yet - a few minutes each week or so.
Anyway, if a [high frequency... |
I am in the process of constructing a kitchen waste digester (vegetable/fruits) from which, hopefully, over time adequate methane may be collected to burn. The digester won't be complete for several months yet - a few minutes each week or so.
Anyway, if a [high frequency high-voltage field][1] were to be applied to ... |
I have seen in some textbooks that reaction is listed under reduction of alkene.
I understand that the double bond is getting reduced to single bond and two hydrogens atoms are added to either of the carbons.
Should I classify this reaction under addition reactions or reduction reactions? |
Is alkene reaction with hydrogen to form alkane an addition reaction? |
Given $2.14g$ of $K_{(s)}$, determine $\Delta Hº_{f,m}$ and $\Delta Uº_{f,m}$ for $K_2O$.
We know:
- The calorimeter's constant: $1849J•K^{-1}$
- The mass of water inside it: $1450g$
- The change in temperature: $2.62K$
- The end product is $K_2O$
The process should be: determining mol of $K_{(s)}$, whi... |
I am living in my dorms at the moment and apparently it is an accepted thing that the water in the building is brown and yellow. According to my RA, this is a characteristic of the town I live in.
The only "clean" water we get is a water filter at the zeroth floor of our building where transparent water comes out.
... |
Contaminated water. A household method to fix this? |
At high temperatures (almost) everything burns to ash. Is ash 'fireproof'?
Is further combustion of ash possible for example by combining with hydrogen, oxygen, etc? |
I am living in my dorms at the moment and apparently it is an accepted thing that the water in the building is brown and yellow. According to my RA, this is a characteristic of the town I live in.
The only "clean" water we get is a water filter at the zeroth floor of our building where transparent water comes out.
... |
Is there a household method to decolorize potentially contaminated water? |
Chemically speaking, what are the biggest differences between suturated fatty acids and unsaturated fatty acids? What are the effects [of those differences] on the geometry of the molecule? And what is the effect of that on our body? |
Surfactants decrease surface tension between two fluids. What do you call a substance that increases the surface tension between two fluids? How is this effect acheived? |
What is the opposite of a surfactant? |
Is there a standard symbol for molar density, i.e. $n/V$, where $n$ is the total number of moles of every species in a system?
I realise that there is standard term "molar volume", which is the reciprocal of what I'm asking for, but my equations are going to look pretty silly with $1/V_m$ written everywhere. As a si... |
Is there a standard symbol for molar density? |
*“unless I am allowed to substitute the additional H on the 2-methylpropane with a Cl”*
Why wouldn't you be? I think that's the key to the answer. |
Merely what the title states there.
An exothermic reaction is apparently one that releases energy to it's environment. According to wikipedia, an explosion is a rapid increase in volume & energy.
Does this mean that an explosion is basically an exothermic reaction? |
Is an explosion merely an exothermic reaction? |
An exothermic reaction is apparently one that releases energy to it's environment. According to [Wikipedia](http://en.wikipedia.org/wiki/Explosion), an explosion is a rapid increase in volume & energy.
Does this mean that an explosion is basically an exothermic reaction? |
The [octane rating][1] of petrol (gasoline) is a measure of the how much compression a fuel air mixture can have before detonating (which in petrol engines is a bad thing as you want the mix to combust only when the spark plug arcs).
What are the key chemical characteristics that determine this rating? What is the m... |
What are the key chemical characteristics that determine the octane rating of fuel? |
scientists are certain that there are no undiscovered elements missing from the periodic table from hydrogen to lawrencium. How? and why? |
In the thermite reaction
2Al(s) + Fe2O3(s) -> 2Fe(l) + Al2O3(s)
what is the maximum temperature attainable by the products? Assume reactants at 25C and 1atm and that all heat capacities remain constant.
I started by using Hess's law to find the enthalpy change of the reaction. I couldn't find a heat of formation for... |
Scientists are certain that there are no undiscovered elements missing from the periodic table from hydrogen to lawrencium. How? and why? |
How can scientists be certain that there are no undiscovered elements missing from the periodic table from hydrogen to lawrencium? |
In the thermite reaction
$$\ce{2Al(s) + Fe2O3(s) -> 2Fe(l) + Al2O3(s)}$$
what is the maximum temperature attainable by the products? Assume reactants at 25°C and 1 atm and that all heat capacities remain constant.
I started by using Hess's law to find the enthalpy change of the reaction. I couldn't find a heat... |
We use scherrer's equation to calculate crystalline size of a particle.
![enter image description here][1]
But which theta should we take from xrd pattern for this calculation.
For example
![enter image description here][2]
Above picture shows the diffraction pattern of nano (above) and bulk (below) sil... |
Is half-full rule and full rule allowed on 6th and 7th period?
<br>Note: Half-full rules is Hund Rules.
Example: What is the right electron configuration?
<br>$W [Xe] 6s^2 4f^{14} 5d^4$ (doesn't use half full rule) or
<br>$W [Xe] 6s^1 4f^{14} 5d^5$ (use half full rule) |
Is half-full rule and full rule allowed on 6th and 7th period? |
I drew the two chair conformers of Beta D-glucose:
![enter image description here][1]
[1]: https://i.stack.imgur.com/dwy92.jpg
Which one is more stable? I think it's the one with all of the OH groups in the equatorial position because of less steric hindrance, but I also know that the anomeric effect make... |
>I also know that the anomeric effect makes the axial one favored as well.
The anomeric effect does stabilize an axial group, but *only* at the anomeric position. Other axial groups are not similarly stabilized. Thus $\alpha$-D-glucose is more stable than you think it should be based on steric considerations alone.
... |
> This gives me a negative temperature, so I assume it is wrong.
Remember that the energy given off as an exothermic reaction progresses is absorbed by the surroundings. The chemical potential energy stored in aluminum and rust is converted into kinetic energy. You are interested in $\Delta H_{surr}$, which should b... |
I recently made self-assembled monolayers (SAMs) of alkanethiols on a copper substrate. After scrubbing off the $\small{\ce{Cu2O}}$ top layer and rubbing the surface with ether and ethanol, I let my copper plates stand in a 5% (w/w) $\small{\ce{NaOH}}$ solution for 5 minutes.
I'm wondering if I could skip this step.... |
As cited in an answer to [this question](http://chemistry.stackexchange.com/q/2461/30), the ground state electronic configuration of Niobium is:
> Nb: [Kr] 5s<sup>1</sup> 4d<sup>4</sup>
Why is that so? What factors stabilize this configuration, compared to the obvious 5s<sup>2</sup> 4d<sup>3</sup> (Aufbau princip... |
How can one explain Niobium’s weird electronic configuration? |
Cu(0) will not be attacked by NaOH, and will not decompose in this aqueous environment at room temperature. So, this is not to create some reaction with the copper. Two uses I can think of:
1. NaOH increases the solubility of Cu<sub>2</sub>O, so maybe this is a way of getting rid of the last remaining copper oxide.
... |
This is an urgent question of mine. It is not homework, it is practicing material for me, but the question is a bit tough and I can't figure it out.
The beginning of the picture, from the word 'Acrylonitril' to the word 'structuurformule:', means the following: *Acrylonitrle reacts with 1,4-butanediamine. When you u... |
The beginning of the picture, from the word 'Acrylonitril' to the word 'structuurformule:', means the following: *Acrylonitrle reacts with 1,4-butanediamine. When you use a lot of acrylonitril, under certain circumstances you almost exclusively get the following:* Then you can see the first of the 2 structural formul... |
I recently made self-assembled monolayers (SAMs) of alkanethiols on a copper substrate. After scrubbing off the $\small{\ce{Cu2O}}$ top layer and rubbing the surface with ether and ethanol, I let my copper plates stand in a 5% (w/w) $\small{\ce{NaOH}}$ solution for 5 minutes, which I then throughly rinsed off with deio... |
When I prepare sodium perborate by mixing sodium hydroxide with metaborate (NaBO2) and hydrogen peroxide and cooling it I applied a test to it by acidifying it with HCl and adding KMnO4. ppt was likely appearing and its turned black. What is the reason ?
and tested another sample of sodium perborate by acidifying i... |
When I prepare sodium perborate by mixing sodium hydroxide with metaborate (NaBO<sub>2</sub>) and hydrogen peroxide and cooling it I applied a test to it by acidifying it with HCl and adding KMnO<sub>4</sub>. A precipitate appeared and it turned black. What is the reason?
I tested another sample of sodium perborate... |
I noted, flipping through the paperback Alfa Aesar catalogue today, that they sell [deuterium-depleted water][1]. Under the usage category, they list 'NMR'. I'm trying to work out what specific use this water has. Unfortunately, on the [basis of very limited clinical evidence][2] of improved cancer outcomes I've been b... |
What is deuterium-depleted water actually used for? |
I know two distinct recipes for cleaning silver:
- Put them into a pot with some club soda and a piece of aluminium foil and pour over a hot water.
- Gently clean silverware with a fine chalk powder (obtained from a pharmacy).
I'd be happy to know:
1. What happens chemically during these procedure - why does ... |
What happens during cleaning silverware? |
> Put them into a pot with some club soda and a piece of aluminium foil and pour over a hot water.
I am familiar with this process. I am not familiar with the other. Perhaps someone else can provide an answer for it.
* What happens chemically during these procedure - why does it work, and what are the byproducts ... |
I was watching this youtube clip ( http://www.youtube.com/watch?v=XY1XLgHUAIQ ) in which a lewis diagram was drawn for a sulfite ion.
Sulfur ends up with four bonds as well as a lone pair of electrons. This gives sulfur 10 electrons. Isn't this too many? |
Is it okay for a sulfite ion to have 10 electrons around the sulfur? |
> **Possible Duplicate:**
> [Can an atom have more than 8 valence electrons? If not, why is 8 the limit?](http://chemistry.stackexchange.com/questions/444/can-an-atom-have-more-than-8-valence-electrons-if-not-why-is-8-the-limit)
<!-- End of automatically inserted text -->
I was watching this youtube clip ( http:/... |
> Put them into a pot with some club soda and a piece of aluminium foil and pour over a hot water.
I am familiar with this process. I am not familiar with the other. Perhaps someone else can provide an answer for it.
* What happens chemically during these procedure - why does it work, and what are the byproducts ... |
A simple test you can do is to boil a large amount of the water and see if a sediment is left in the vessel. This will tell you certain things about you contaminant.
- Is it particulate? We expect so because a filter is removing the contaminant.
- Is it's boiling point below that of water?
If you get a residue w... |
in a voltaic cell there is zinc and copper and the electrolyte is sodium chloride solution. The question was In this cell which of the following undergoes reduction?
my answer was copper but why is the exact answer is hydrogen ion???? |
In a Voltaic cell there is zinc and copper and the electrolyte is sodium chloride solution. The question was In this cell which of the following undergoes reduction?
My answer was copper, but why is the exact answer is hydrogen ion? |
Copper cannot undergo reduction because, in the list of components of the cell you listed, it is only present in its most reduced state, Cu(0). Thus, it cannot be copper that is reduced. See [here](http://scienceline.ucsb.edu/getkey.php?key=2466) for additional hints about your system.
You may have been confused by ... |
I know two distinct recipes for cleaning silver:
- Put them into a pot with some club soda and a piece of aluminium foil and pour over a hot water.
- Gently clean silverware with a fine chalk powder (obtained from a pharmacy).
I'd be happy to know:
1. What happens chemically during these procedure - why does ... |
In a voltaic cell there is zinc and copper and the electrolyte is sodium chloride solution. The question was: `In this cell which of the following undergoes reduction?`
My answer was copper, but why is the exact answer a hydrogen ion? |
Which of the following undergoes reduction in a voltaic cell? |
If we have a benzene with a single substituent, such as chlorobenzene, what do we call the carbon atom to which the group is attached? I'm familiar with the ortho- meta- para- nomenclature, but the last one escapes me. |
What is the name of the "primary" carbon in a benzene derivative? |
For some DFT calculations I performed with localized (Gaussian) basis sets, I wonder how the basis sets I used are properly named. The names I could gather are:
- H, C and O: 6-311G(d,p)
- Al: 8-511G*
- Ga: 86-4111d41G
(They all come from [this website](http://www.crystal.unito.it/Basis_Sets/Ptable.html).)
... |
When carbon combusts with oxygen, is this considered a redox reaction since the oxygen atoms gain electrons and the carbon atoms lose them? |
Is combustion considered a redox reaction? |
In a voltaic cell there is zinc and copper and the electrolyte is sodium chloride solution. The question was:
>In this cell, which of the following undergoes reduction?
My answer was copper, but why is the exact answer "a hydrogen ion"? |
What undergoes reduction in a Zn-Cu voltaic cell? |
I am studying different means of collecting water for consumption. From resources available on Internet, I understand that distilled water is not advised for regular consumption because of the lack of minerals and salts, while rainwater can be consumed if not overloaded with unwanted chemicals.
What confuses me is t... |
What is the difference between distilled water and rainwater? |
Rain water passes through the atmosphere and picks up whatever is present there, including particulates such as dust, trace amounts of atmospheric gases, nitrates and nitrites, and so forth.
Rain water is relatively low in mineral content. In practice, people drink rainwater from streams and wells, where it has had... |
Pretty much what the title states.
Would a high voltage ( of the order of a few score kV ) drive electrolysis? Or, Does it require a large current and low voltage? Or, Electrolysis require both large voltage & large current? |
Does potential difference, or current drive electrolysis? |
Would a high voltage ( of the order of a few score kV ) drive electrolysis?
Or, does it require a large current and low voltage? Alternatively, does electrolysis require both large voltage & large current? |
Does potential difference or current drive electrolysis? |
What alloys can be used to make a metal pencil like this one?
![enter image description here][1]
http://www.wired.com/gadgetlab/2010/09/neither-pen-nor-pencil-write-endlessly-in-metal/
[1]: https://i.stack.imgur.com/HqANd.jpg |
I am trying to build a homemade thermos. It needs to be able to conserve the heat in 125ml of water for 15 minutes.
However, unlike a normal thermos, it also needs to be able to be heated. What homemade substances can I use that are not flammable, yet provide a relatively high degree of insulation?
Note that my ... |
Are there any nonflammable thermal insulators which can be made at home? |
If I am given the molarity of two substances and I know how they react, how can I write the balanced chemical reaction? ie)
Experimentally I found:
1.0 M $NH_3$(aq) mixed with 0.1 M $BaCl_2(aq)$ yielded NO precipitate when 1ml of each were mixed together. My unbalanced chemical equation so far looks like
$N^{... |
Have you considered the possibility that your reaction is wrong. where, for example, is the barium on the product side. I'll give you one hint here: barium chloride dissociates in water to barium and chloride ions. Ammonia reacts with water to produce some ammonium ion and the same amount of hydroxide ion. However... |
If I am given the molarity of two substances and I know how they react, how can I write the balanced chemical reaction? I.e.,
Experimentally I found:
1.0 M $NH_3$(aq) mixed with 0.1 M $BaCl_2(aq)$ yielded NO precipitate when 1ml of each were mixed together. My unbalanced chemical equation so far looks like
... |
What alloys can be used to make a metal pencil like [this one](http://www.wired.com/gadgetlab/2010/09/neither-pen-nor-pencil-write-endlessly-in-metal/)?
![enter image description here][1]
[1]: https://i.stack.imgur.com/HqANd.jpg |
If I am given the molarity of two substances and I know how they react, how can I write the balanced chemical reaction? I.e.,
Experimentally I found:
1.0 M $NH_3$(aq) mixed with 0.1 M $BaCl_2(aq)$ yielded NO precipitate when 1ml of each were mixed together. My unbalanced chemical equation so far looks like
... |
How can Acetic acid be distilled by freezing when its freezing point is above the freezing point of water.
Examples on the web show water part of the vinegar as ice and acid as liquid but wikipedia shows that freezing point of acetic acid is 16.6C.
Just confused??
Thank you
|
How do I type a simple chemical equation in Microsoft Word? I can do subscripts, but long arrows are harder - they do not align with the text. Also, if I want to show a delta above the arrow for heat, I cannot do that. I have tried the Chemistry add-on from Microsoft, but that does not help with equations. |
How do I type a simple chemical equation in Microsoft Word? |
I knew will learning about electrolysis that if the ionic compound is molten it becomes free moving ions. If that is the case, what will happen if i continued heating till reaching the boiling point so the ionic compound evaporates.Will it still free moving ions? |
Will gaseous ionic compounds be free moving ions? |
I knew while learning about electrolysis that if the ionic compound is molten it becomes free moving ions.
If that is the case, what will happen if I continued heating till it reaches the boiling point so that the ionic compound evaporates?
Will it still be free moving ions? |
I recently heard a talk from a physicist about experiments on simple two-atom molecules in vacuum that showed that certain behaviour of the molecules was explained by quantum entanglement. Now this experiment was about creating holes in the inner electron shells of the molecule, so pretty much in the realm of physics a... |
Can quantum entanglement affect the chemistry of molecules? |
I want to know what is the phenomenon and explanation behind this corrosion?What is the reaction? |
Why lithium and sodium corrode easily? |
Why can dissolution reactions (e.g. dissolution of calcium chloride) be exothermic? |
Dissolution reactions are normally endothermic, and crystallization reactions are normally exothermic, but there are some exceptions -- such as the dissolution of calcium chloride. Why is this so? |
I am reading up on boron in my notes and there is a certain paragraph that I do not understand
> The tendency of B to form B-B bonds is less pronounced than that of
> carbon, its periodic table neighbor on the right, to form C-C bond,
> but it is much greater than that of the nearest element in the group,
> Al, t... |
I want to know what is the phenomenon and explanation behind this corrosion?
What is the reaction? |
Why do lithium and sodium corrode so easily? |
I remember my Physical Chemistry Professor saying that very tiny negative Kelvin temperatures have been achieved on the quantum level. Is this true? |
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