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What's the chemistry behind only charging a Lithium-ion battery to 80% capacity at most, to increase its lifespan?
Over on the Skeptics StackExchange, a question has come up about [charging Lithium-ion cells to just 80% of their maximum, in order to extend their lifetime][1].
Is there a sound basis in chemistry f... |
What's the chemistry behind only charging a Lithium-ion battery to 80% capacity at most, to increase its lifespan? |
I know how to calculate the specific heat, but not molar specific heat. What is molar specific heat and how do you calculate it? |
How do you calculate molar specific heat? |
While drinking milk (or better 'while seeing the milk I'm gonna drink') a question came up to my mind:
Why does the milk sometimes flake, even if not in contact with some other substances?
I guess the correct term to use is *flocculation*, at least this is the word that raises up when talking about cheese product... |
Why does milk flake? |
I think the right word for it is **curdle**. Have you read, for example, the [Wikipedia article on *curd*](http://en.wikipedia.org/wiki/Curd)? It says:
> *“Milk that has been left to sour (raw milk alone or pasteurized milk with added lactic acid bacteria or yeast) will also naturally produce curds, and sour milk ch... |
Could anyone tell me how I would go about calculating the pH of 100.0 mL of 0.100 M $H_2NNH_2$ ($K_b = 3.0 \times 10^{-6}$).
Furthermore, how would this pH change when 20.0 mL of 0.200 M $HNO_3$ is added to the solution?
I'm not looking for only an answer, but rather the general method to solve these types of pr... |
How can I determine the pH of solution? |
Could anyone tell me how I would go about calculating the pH of 100.0 mL of 0.100 M $H_2NNH_2$ ($K_b = 3.0 \times 10^{-6}$).
Furthermore, how would this pH change when 20.0 mL of 0.200 M $HNO_3$ is added to the solution?
I'm not looking for only an answer, but rather the general method to solve these types of pr... |
This was some homework that was due earlier that I never exactly understood. Hoping someone can clarify this concept for me:
We are asked to sort these four acids by increasing Bronsted acidity:
![sort these four acids by increasing Bronsted acidity][1]
The problem is, I am confused why H$_2$F$^+$ is the stron... |
Is this the correct relative Bronsted Acidity in these four acids? |
Liquid nitrogen seems to be attracting a bit of attention at the moment as a medium of energy storage, both for electricity grid applications and for transport.
What is the energy density of liquid nitrogen, per unit volume and per unit weight, assuming we'll be bringing it up to 20°C, 1 bar? How does this compa... |
What's the energy density of liquid nitrogen? |
[Liquid nitrogen][1] seems to be attracting a bit of attention at the moment as a medium of energy storage, both for electricity grid applications and for transport.
For example, [Highview][2] are doing round-trip electricity storage via liquid nitrogen.
![enter image description here][3]
The [Dearman Engine ... |
Can we separate positive ions from negative ions in a solution? |
While it is true that solutions are not always locally electroneutral, that non-neutrality is small, and does not extend to larger scale. Thus, it does not impact chemical concentrations: **you cannot separate positive and negative charges in a solution** at a macroscopic level. See for example this excerpt from [*Ioni... |
While drinking milk (or better 'while seeing the milk I'm gonna drink') a question came up to my mind:
Why does the milk sometimes flake, even if not in contact with some other substances?
I guess the correct term to use is *flocculation*, at least this is the word that raises up when talking about cheese product... |
If I buy a loaf of freshly-made bread and leave it out at room temperature for a day or two, when I reach into the bag the air inside is much warmer than the rest of the room. Why? |
Why is bread warm at room temperature? |
For example, consider a pot of water with a drop of oil floating on it, with surfactants present in the water.
Will the surfactants in the water spread evenly across all three interfaces (water/metal, water/air, and water/oil)?
Are there material-specific surfactants, such that each of the three interfaces might ... |
How do surfactants spread in the case of multiple materials? |
For water and on macroscopic level we can't, as there is non-zero water dissociation constant.
Dropping solvent dissociation from consideration, we should consider molar charge. Faraday's number is molar charge and it is ~10^5 Coulomb/mol. So, if you can store really much charge (at least some Coulombs) in your sol... |
The difficulty in talking about hybridization lies in the fact that it tends to confuse atomic and molecular orbitals, or (equivalently?) one- and many-electron wave functions.
Mixing atomic orbitals generally only becomes possible when we do a mathematical approach which treats more than one electron at once. That,... |
I was wondering, how can I clean my RBF after doing a distillation? Cleaning it with a simple pipe-cleaner or similar cleaner is a headache, due to the *roundness* of the flask. Any good advice? |
I was wondering, how can I clean my RBF after doing a distillation? Cleaning it with a simple pipe-cleaner or similar cleaner is a headache, due to the *roundness* of the flask.
Is there a more effective method? |
Just skimmed over the links:
**Highview**:
> Using ambient heat to warm it, the process **recovers around 50 per cent of the electricity that is fed in**, says Highview's chief executive Gareth Brett. The efficiency **rises to around 70 per cent** if you harness waste heat from a nearby industrial or power plant t... |
While writing up a lab for biology, I realized that the dialysis tubing for sale <a href="http://www.sigmaaldrich.com/labware/labware-products.html?TablePage=21942948">online</a> seemed to retain large molecules (12-14,000 Da) but didn't specify an upper bound. I learned that the tubing is impermeable to <a href="http:... |
Why is dialysis tubing impermeable to sucrose when it should retain >12,000 Da? |
While writing up a lab for biology, I realized that the dialysis tubing for sale <a href="http://www.sigmaaldrich.com/labware/labware-products.html?TablePage=21942948">online</a> seemed to retain large molecules (12-14,000 Da) but didn't specify an upper bound. I learned that the tubing is impermeable to <a href="http:... |
PEP (Phosphoenolpyruvic acid) is acidic but I need to make it neutral. I need a solution (pH 6-8) of PEP in a final 1 mL volume with a concentration of 100 mM. How would I make this? |
PEP (Phosphoenolpyruvic acid) is acidic but I need to make it neutral. I need a solution (pH 6-8) of PEP in a final 1 mL volume with a concentration of 100 mM.
How would I make this? |
How would I neutralize a PEP (Phosphoenolpyruvic) acid? |
Here's a good link as an introduction to DRIE:<br>
[BSAC: DRIE Process Development][1]<br>
The $C_4F_8$ (refer Pg. 4 on the link) passivates the entire top layer. But when $SF_6$ ion bombardment occurs, only the region not covered by the mask is etched. Why does the passivation layer protect just the mask and not t... |
Why does the passivation layer in DRIE protect just the mask and not the substrate? |
I'm gonna get kicked all the way to the Moon, but whatever.
I am doing some nitroglycerin. I know the process, since the reaction itself is pretty basic. I know that it is an electrophilic substitution and that it releases a hell lot of energy. I've handled that with an ice bath and by doing the respective stoichiom... |
Here's a good link as an introduction to DRIE:<br>
[BSAC: DRIE Process Development][1]<br>
The $C_4F_8$ (refer Pg. 9 on the link) passivates the entire top layer. But when $SF_6$ ion bombardment occurs, only the region not covered by the mask is etched. Why does the passivation layer protect just the mask and not t... |
Since there is no liquid state of carbon dioxide, what will carbon dioxide turn into when exposed to high pressure? |
If gases turn into liquids under pressure, what does carbon dioxide turn into? |
There is a liquid state for carbon dioxide. Borrowing the $\ce{CO2}$ [phase diagram][1] from Wikipedia, we can see that $\ce{CO2}$ will condense at a few atmospheres, dependent on temperature. At still higher pressures, the liquid will solidify. Below the triple point temperature, the gas will transition directly to so... |
Why do molecules like methoxyethane, ethoxyethane and so on have lower boiling points than isomeric alcohols? It has something to do with the structure, but I don't exactly know what it is.. |
Why do molecules like methoxyethane, ethoxyethane and so on have lower boiling points than isomeric alcohols?
I think it has something to do with the structure, but I don't exactly know what it is. |
What is the chemical reactions responsible for the break down of valine in the body.
I know oxidative deamination is part of the process but how is valine further broken down from an keto acid to isobutyrate? |
What is the chemical reactions responsible for the breakdown of valine in the body.
I know oxidative deamination is part of the process but how is valine further broken down from an keto acid to isobutyrate? |
How does dichlorotriazenetrione supply chlorine to a swimming pool and how does it oxidize organic material? |
I'm thinking of sucrose, which I <a href="http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=5988">learned</a> is nonreducing, what I take to mean it doesn't accept/take electrons from the surrounding solution. Does this also mean that it doesn't ionize and thus has a <a href="http://en.wikipedia.org/wiki/Van_%27t... |
If a sugar is nonreducing, does that mean it doesn't ionize in water? |
I'm thinking of sucrose, which I <a href="http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=5988">learned</a> is [nonreducing][1], what I take to mean it doesn't accept/take electrons from the surrounding solution. Does this also mean that it doesn't ionize and thus has a <a href="http://en.wikipedia.org/wiki/Van... |
It would be important to know what kind of "separation" you are talking about -- spectral separation, which would just mean suppression on the spectroscopic response from undesired species, or physical separation, where you actually remove those species from your sample?
The problem is that not only may your sample ... |
I have drawn the figures and determined intuitively that the larger molecule's C-C would break first. I made this assumption that ethane has the stronger C-C bond and I am correct, however I do not understand the underlying reasons why.
In both molecules we have single bonds, but in ethane we have more space for the... |
Which C-C bond would break first, the one in ethane, or 2,2-dimethylpropane? |
Why are smoke odors persistent in fabrics? |
I'm not sure how to approach this problem as part of my online Chemistry homework.
"A backpacker wants to carry enough fuel to heat 3.0 of water from 20°C to 100.0°C. If the fuel he carries produces 36 kJ of heat per gram when it burns, how much fuel should he carry? (For the sake of simplicity, assume that the tran... |
How to calculate solubility of CaF₂ at different temperatures? |
I'm not sure how to approach this problem as part of my online Chemistry homework.
"A backpacker wants to carry enough fuel to heat 3.0 kg of water from 20°C to 100.0°C. If the fuel he carries produces 36 kJ of heat per gram when it burns, how much fuel should he carry? (For the sake of simplicity, assume that the t... |
I'm not sure how to approach this problem as part of my online Chemistry homework.
"A backpacker wants to carry enough fuel to heat 3.0 kg of water from 20°C to 100.0°C. If the fuel he carries produces 36 kJ of heat per gram when it burns, how much fuel should he carry? (For the sake of simplicity, assume that the t... |
By 25° Celsius, I used the free energy table for $\small G$ for the reaction and got $\small K_{sp}= 10^{-9.02}$.
I now need to find out what the solubility is by 10, 20 and 30°C. Could you also show what equation you used and how to work out the solubility by one of these other temperatures? |
How to calculate the solubility of CaF₂ at different temperatures? |
It depends what you have access to… but if we suppose that you have access to decent thermodynamic tables, here's a hint:
You know how solubility is linked to dissolution reaction (Gibbs) free energy. Now, how does the free energy depend on temperature? In other words, what is $\displaystyle\frac{\partial G}{\partia... |
There are lots of softwares like schrodinger maestro, argus lab which is used for simulations of docking.But i always fascinated how these softwares works,what is the fundamental principle for working of these kind of sofware.Lets say if i want to make a simple software which when i input the atoms and atom number(eg:C... |
There are lots of software packages like Schrödinger Maestro or Argus Lab, which are used for simulations of docking.
I have always been fascinated as to how such software works. What is the fundamental principle working "under the hood" of this kind of sofware?
Let's say I wanted to make a simple piece of so... |
How does simulation software work at a fundamental level? |
In more powerful toothpastes, like Crest Pro-Health, stannous fluoride is used in place of sodium fluoride.
According to [Wikipedia](http://en.wikipedia.org/wiki/Tin(II)_fluoride):
> Stannous fluoride converts the calcium mineral apatite into fluorapatite, which makes tooth enamel more resistant to bacteria gener... |
Why is tin (II) fluoride more effective in turning apatite into fluorapatite? |
I am a bit unclear on the definition of salinity. I have always thought of it as simply total dissolved ions.
Wikipedia seems to agree "saltiness or dissolved salt content" but many other sources seem to suggest that only certain ions contribute.
So is there a list of specific anions and cations that contribute t... |
What is the exact definition of Salinity? |
What are the chemical reactions responsible for the breakdown of valine in the body?
I know oxidative deamination is part of the process but how is valine further broken down from an keto acid to isobutyrate? |
Can a polypropylene 55 gallon drum previously filled with chemicals used in the chrome plating process (possibly Nickel Sulfate) ever really be "cleaned out" for re-use? Can polypropylene ever absorb and retain such chemicals, or are these drums practical for this use because they do not? |
For example, in phosphorus pentachloride five orbitals hybridize, but why not 6, as in the hydrated Al ion? I have read that the reason six orbitals hybridize is that a maximum of six oxygens can stably fit around it. Why is it not the same case for phosphorus?
Secondly, why does water $sp^3$ hybridize even though it ... |
In orbital hybridization, what determines the number of orbitals that hybridize to be at the same energy level? |
In orbital hybridisation, what determines the number of orbitals that hybridise to be at the same energy level? |
Is there an exothermic reaction which produces 1 to 2 minutes of heat at around 175 degrees Fahrenheit, no toxic gasses and is considered to be more or less safe?
Thank you. |
Is there an exothermic reaction which produces 1 to 2 minutes of heat at around 175 degrees Fahrenheit, no toxic gasses and is considered to be more or less safe? |
A [recent news report][1] in the UK claimed a breakthrough in making a petrol equivalent from carbon dioxide and water:
>A small British company has produced the first "petrol from air" using a revolutionary technology that promises to solve the energy crisis as well as helping to curb global warming by removing car... |
What is the chemistry behind this "petrol from air" technology? |
If water is mixed with lard oil and heated (creating some *super-critical* liquid with water), how does this affect the volatility of the mixture in comparison with its *purity*..?
So, My question is: What happens when a mixture of lard oil and water is compressed and then heated to over 800 degrees fahrenheit almos... |
What would happen to a Water/Lard Mix under pressure and high heat? |
If water is mixed with lard oil and heated (creating some *super-critical* water), how does this affect the volatility of the mixture in comparison if it is a pure mix of either water, or lard oil?
So, My question is: What happens when a mixture of lard oil and water is compressed and then heated to over 800 degrees... |
[OLED displays][1] have been emerging as competitors for LCD displays for some time and are now common in mobile phones (see comparison of a Google Nexus 1 and an iPhone [here][2])
The displays use small molecules or polymers that emit light when a current is passed through them (like a semiconductor LED). But what ... |
What sort of molecules or polymers are used in OLED displays? |
If water is mixed with lard oil and heated (creating some *super-critical* water), how does this affect the volatility of the mixture in comparison if it is a pure mix of either water, or lard oil?
What happens when a mixture of lard oil and water is compressed and then heated to over 800 degrees Fahrenheit almost i... |
I seek to put a layer of fluorine on a 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 intensive "all of chemis... |
How to fluorinate polyethylene? |
What is the meaning of $ (en) $ on this two coordination compounds:
$[Co(en)_2(NO_2)_2]Cl$
<br>
$[Cd(en)_2(CN)_2]$
Is it a type of compound? If yes, what is the meaning? |
What is the meaning of '(en)'? |
Thought experiment
Given two glasses of water, how would one detect which glass contains heavy water, and which contains potable water without using complicated laboratory equipment?
Something like the way a piece of litmus paper (yes, it is laboratory equipment and **easily available to the layman** at that!) m... |
Is there a simple field test for heavy water? |
Which would have one monochlorination possibility? 2,2-dimethylpropane or 2-methylpropane
It seems I'm missing something because I thought both would only have one monochlorination possibility. (unless I am allowed to substitute the additional H on the 2-methylpropane with a Cl?)
Thanks! |
Which has one monochlorination possibility? |
If you don't have access to a freezer (you are in the field right?), you could allow sun light to pass through
your glass vessels and then through a prism. The heavy water will absorb less orange red light and the difference might be observable.
![enter image description here][1]
One of [these][2] might help... |
Mass. Heavy water is noticeably heavier then light water. Simply weigh an equal amount of each water and see which weights more.
Light water weights 1 g/mL ([0.99700 g/mL at 25 °C][1])
[Heavy water weights 1.107 g/mL at 25 °C][2]
So if you have 100 mL you will see an 11 g difference, assuming pure samples.
... |
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... |
I am reading some articles about the electronic properties of graphene and while reading it i came across graphene armchair and zigzag strutures ;both having different band strutures. The two different orientation (armchair and zigzag) is due to the arrangement of carbon atoms in periphery ([wiki][1]) but i am unable t... |
Which would have one monochlorination possibility?
**2,2-dimethylpropane**:
![enter image description here][1]
or **2-methylpropane**:
![enter image description here][2]
It seems I'm missing something because I thought both would only have one monochlorination possibility. (unless I am allowed to subst... |
What do graphene "armchair(5,5)" and "zigzag(5,0)" refer to? |
I am not sure where to start with this problem. I know that q = mc(Tf-Ti), but that seems like it would not help here. I think I need to balance the equation, but I am not sure how the rate factors into the problem. Anyway, if anyone could help me find the relevant equations/method for solving this problem, it would be... |
I am not sure where to start with this problem. I know that $\small q = mc(T_f-T_i)$, but that seems like it would not help here. I think I need to balance the equation, but I am not sure how the rate factors into the problem. Anyway, if anyone could help me find the relevant equations/method for solving this problem, ... |
I'm here to share with you something that totally confuses me, as I can't see the logic behind it, and my teacher doesn't know either.
Let's take a set of bonds that's trigonal pyramidal, with a lone pair of electrons and three bonds. The angle between the bonds is 107 degrees.
Now, the part where I get confuse... |
Why do single, double and triple bonds repel each other equal amounts? |
I'm here to share with you something that totally confuses me, as I can't see the logic behind it, and my teacher doesn't know either.
Let's take a set of bonds that's trigonal pyramidal, with a lone pair of electrons and three bonds. The angle between the bonds is 107 degrees.
Now, the part where I get confuse... |
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