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It turns out pineapple juice can dissolve a jello set, and turn a beef roast to paste.
It turns out this is caused by [Bromelain][1], an enzyme sometimes used in meat tenderising.
I'm trying to work out how you can eat pineapple without dissolving on the spot.
My question is: **How does the human body process Bromel... |
How does the human body process Bromelain in pineapple? (A meat tenderising/dissolving enzyme) |
There is another rather more simple answer to the question:
$\ce{SnCl2}$ can be thought of as a salt to a much greater extent than $\ce{SnCl4}$. In fact, tin is so often thought of as a metal, that it takes some people time to understandt that $\ce{SnCl4}$ is in fact not a salt but much more a molecule.
Then, whe... |
Consider the following:
$\ce{PbS(s) + \frac{3}{2}O2(g) -> PbO(s) + SO2(g)}~~~\Delta H^\circ= -413.7~\mathrm{kJ}$
$\ce{PbO(s) + C(s) -> Pb(s) + CO(g)}~~~\Delta H^\circ = +106.8~\mathrm{kJ}$
a. Calculate the enthalpy of the following process:
$\ce{PbS(s) + \frac{3}{2}O2(g) + C(s) -> Pb(s) + SO2(g) + CO(g)}$
... |
![enter image description here][1]
[1]: https://i.stack.imgur.com/4IAvr.jpg
My try:
Energy given by reaction = 1690 kJ
Temperature of Ice = 0 oC
Final temperature = 50 oC
C water = 4.18 J g-1* K
?Hfus ice = 6.01 kJ*mol-1
Mass of ice = ?
When the heat is absorbed by the ice then ice will mel... |
The [MG811](https://www.google.es/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved=0CDQQFjAF&url=http%3A%2F%2Fwww.olimex.cl%2Fpdf%2FCO2b.pdf&ei=hs12VYOPEYHlUaLOgcAF&usg=AFQjCNEyRdKTIKGQSLkfYsuZSJgMhy0lKw&sig2=bBJ8VvzA2ZgxPB1CDdYTaQ&bvm=bv.95039771,d.d24&cad=rja) is an electrochemical sensor that measures CO2. I copy you th... |
How does the MG811 sensor work? |
The [MG811](https://www.google.es/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved=0CDQQFjAF&url=http%3A%2F%2Fwww.olimex.cl%2Fpdf%2FCO2b.pdf&ei=hs12VYOPEYHlUaLOgcAF&usg=AFQjCNEyRdKTIKGQSLkfYsuZSJgMhy0lKw&sig2=bBJ8VvzA2ZgxPB1CDdYTaQ&bvm=bv.95039771,d.d24&cad=rja) is an electrochemical sensor that measures $\ce{CO2}$. I copy... |
The [MG811](https://www.google.es/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved=0CDQQFjAF&url=http%3A%2F%2Fwww.olimex.cl%2Fpdf%2FCO2b.pdf&ei=hs12VYOPEYHlUaLOgcAF&usg=AFQjCNEyRdKTIKGQSLkfYsuZSJgMhy0lKw&sig2=bBJ8VvzA2ZgxPB1CDdYTaQ&bvm=bv.95039771,d.d24&cad=rja) is an electrochemical sensor that measures $\ce{CO2}$. I thin... |
In the reaction, OH<sup>-</sup> group attacks a hydrogen ion in an E2 reaction, forming a transition state in which simultaneously N(CH<sub>3</sub>) is removed. In this reaction, the OH<sup>-</sup> should attack, like in other case of E2 so as to form the Zaitsev product, but due to "steric hindrance" the less substitu... |
Why is the less substituted alkene favoured in Hofmann elimination? |
Reliable automatic addition of hydrogens and charge assignment to small molecules at given pH? |
Why does magnesium have a lower melting point than both calcium and beryllium? It does not seem to fit into the group trend. |
![enter image description here][1]
[1]: https://i.stack.imgur.com/4IAvr.jpg
My new try:
Given data
Energy given by reaction =1690 kJ
Initial temperature = 0 oC
Final temperature = 50 oC
C water = 4.18 J*mol-1* K-1
?Hfus ice = 6.01 kJ*mol-1
Calculate Mass of ice = ?
Ice melts at constant ... |
##Part 1:
It's easier to imagine \begin{equation}\ce{A + B -> C + D} \tag{1}
\end{equation}
\begin{equation}\ce{D + E -> F + G} \tag{2}\end{equation}
\begin{equation}\end{equation}
Now if we wanted to write a 3rd equation where both the reactions 1 and 2 happen, we'd get
\begin{equation}\ce{A + B + E -> C + F + G... |
Why does magnesium have an exceptionally low melting point? |
Are there gases that are not transparent at room temperature (i.e. at temperature below the point where the substance starts to radiate visible light due to heating)? |
Are there non-transparent gases? |
In the reaction, $\ce{OH-}$ group attacks a hydrogen ion in an E2 reaction, forming a transition state in which simultaneously $\ce{NCH3}$ is removed. In this reaction, the $\ce{OH-}$ should attack, like in other case of E2 so as to form the Zaitsev product, but due to "steric hindrance" the less substituted alkene is ... |
The amino acids are Zwitterions. In neutral pH, an Amino acids amino terminal has a + postive charge and acid terminal has - negative charge. They cancel each others charge thanks to the H that's roaming between the two terminals.
But, I am not able to get why Amino acids have positive charges at a low pH and negati... |
Why amino acids (Zwitterion) become either negative or positive at low and high pH solutions? |
I am trying to compute the NMR shift for a specific atom in the middle of the surrounding crystal unit cell (1 surrounding anion sphere and 1 cation sphere) in Gaussian09. I only need the chemical shift for the middle atom.
How can I only compute the shift for this atom, and leave out the rest? And would it even sa... |
How to compute the NMR shift in Gaussian09 for only one specific atom in a bigger unit cell? |
I am trying to compute the NMR shift for a specific atom in the middle of the surrounding crystal unit cell (1 surrounding anion sphere and 1 cation sphere) in Gaussian09. I only need the chemical shift for the middle atom.
How can I only compute the shift for this atom, and leave out the rest? And would it even sa... |
It seems like you have the right idea to me,
For the "Initial Rate," you're taking a curve and doing a straight approximation of the curve over a small portion, as you appear to be doing.
Your logic also appears correct to me, a decrease in concentration should correspond to a negative rate.
My guess is that ... |
While studying about bonding there was one statement that "pi bonds can only be formed only with sigma bonds" as we know that in double bond there is 1 sigma bond and 1 pi bond but then one question arises: Why is a pi bond formed only when a sigma bond is formed? Is it possible to form a pi bond without any formation ... |
Why are pi bonds only formed when sigma bonds are formed? |
I'm looking for some kind of email list, forum, or group that discusses chemistry demonstrations. I'm working on an improvement to a demo that's been used for a few decades at my institution and I'm looking for a other few people (that aren't at my institution) to try it out and give feedback. Any ideas? |
The amino acids are Zwitterions. In neutral pH, an Amino acids' amino group has a + postive charge and Carboxyl group has - negative charge. They cancel each others charge thanks to the H that's roaming between the two groups.
But, I am not able to get why Amino acids have positive charges at a low pH and negative a... |
I am visualizing some molecules with Molden. Is there a way to hide hydrogens, without deleteing the hydrogen entries from the structur file? |
Hide hydrogens in Molden? |
I am visualizing some molecules with Molden. Is there a way to hide hydrogens, without deleting the hydrogen entries from the structure file? |
First, a little bit of background. Transparency is not an absolute property of a material. *Every* substance is opaque, so long as light has to pass through enough of it, and opacity also changes according to ambient conditions. Some substances, such as most metals, are opaque even in $100\ \mathrm{nm}$ thin films, wh... |
First, a little bit of background. Transparency is not an absolute property of a material. *Every* substance is opaque, so long as light has to pass through enough of it, and opacity also changes according to ambient conditions. Some substances, such as most metals, are opaque even in $100\ \mathrm{nm}$ thin films, wh... |
My question is regarding setting up this equation. My givens are as follows:
- Gases are helium, then methane, then hydrogen. (Test all three)
- Assume balloon is spherical.
- Assume temperature is $25~\mathrm{^\circ C}$
So I need to find the diameter of the balloon needed to life a 7lb cat. I setup my equat... |
First, a little bit of background. Transparency is not an absolute property of a material. *Every* substance is opaque, so long as light has to pass through enough of it, and opacity also changes according to ambient conditions. Some substances, such as most metals, are opaque even in $100\ \mathrm{nm}$ thin films, wh... |
> Is there a general way to predict products of a chemical reaction, given only the atomic masses of masses of all elements involved?
Unforturnately, no.
>If there's no method to do so, are we supposed to memorize all chemical reactions?
There is some amount of reactions one have to memorize individually. Ho... |
If 5ml alcohol is dissolved in 1 L of water ( the purpose is to highlight the low quantity of one of the liquids) , how is it possible for 5 ml to evenly dissolve in 1 L of water ? There is not enough of alcohol to sit between water molecules , isn't it ? So how is the mixture's proportion/composition is uniform ?
O... |
homogeneous mixture - Are they truly uniform in composition and proportion? |
First, a little bit of background. Transparency is not an absolute property of a material. *Every* substance is opaque, so long as light has to pass through enough of it, and opacity also changes according to ambient conditions. Some substances, such as most metals, are opaque even in $100\ \mathrm{nm}$ thin films, wh... |
- What are the different properties that intermolecular forces and Intramolecular forces attribute to? _i.e._ intermolecular forces contribute to BPs, vapor pressures, etc.
Specific problem: why does **n-butylamine** have lower vapor pressure at room temperature than **methanol**? Explain in regards to IMFs. |
If 5ml alcohol is dissolved in 1 L of water ( the purpose is to highlight the low quantity of one of the liquids) , how is it possible for 5 ml to evenly dissolve in 1 L of water ? There is not enough of alcohol to sit between water molecules , isn't it ? So how is the mixture's proportion/composition is uniform ?
O... |
Why isn't the [Silicone analogue of Benzene](http://www.rsc.org/chemistryworld/News/2010/January/29011001.asp) flat? As far as I understand, Silicon and Carbon make similar structures and it doesn't make sense that it's benzene analogue should be substantially different.
![enter image description here][1]
[... |
Why isn't the Silicon analogue of Benzene flat? |
![enter image description here][1]
Suppose you have this spectrum and the molecular formula of $C_{10}H_{12}O$
The structure is
![enter image description here][2]
My problem is with the peak at ~7 which is an H-Benzene signal, with quartet splitting and a relative area of 4. Surely this means that the benz... |
![enter image description here][1]
Suppose you have this spectrum and the molecular formula of $\ce{C10H12O}$
The structure is
![enter image description here][2]
My problem is with the peak at ~7 which is an H-Benzene signal, with quartet splitting and a relative area of 4. Surely this means that the benze... |
![enter image description here][1]
Suppose you have this spectrum and the molecular formula of $C_{10}H_{12}O$
The structure is
![enter image description here][2]
My problem is with the peak at ~7 which is an H-Benzene signal, with quartet splitting and a relative area of 4.
Surely this means that:
... |
![enter image description here][1]
Suppose you have this spectrum and the molecular formula of $\ce{C10H12O}$
The structure is
![enter image description here][2]
My problem is with the peak at ~7 which is an H-Benzene signal, with quartet splitting and a relative area of 4. Surely this means that the benze... |
![enter image description here][1]
Suppose you have this spectrum and the molecular formula of $C_{10}H_{12}O$
The structure is
![enter image description here][2]
My problem is with the peak at ~7 which is an H-Benzene signal, with quartet splitting and a relative area of 4.
Surely this means that:
... |
![enter image description here][1]
Suppose you have this spectrum and the molecular formula of $\ce{C10H12O}$
The structure is
![enter image description here][2]
My problem is with the peak at ~7 which is an H-Benzene signal, with quartet splitting and a relative area of 4.
Surely this means that:
... |
![enter image description here][1]
Suppose you have this spectrum and the molecular formula of $\ce{C10H12O}$
The structure is
![enter image description here][2]
My problem is with the peak at ~7 which is an H-Benzene signal, with quartet splitting and a relative area of 4.
Surely this means that:
... |
How do we name $\ce{Cl2CHCH2COOH}$ ?
Is seeing branched chain our number 1 priority so we name it
1,1-dichloro-3-propanoic acid?
also
Which is more acidic $\ce{Cl2CHCOOH}$ or $\ce{Cl2CHCH2COOH}$ ?
I feel it should be the first one as there is more −I effect but not sure.
|
What are intermolecular molecular forces?<br/>
The forces(electrostatic force) between molecules of a compound. These forces are responsible for intermolecular distances and how tightly the molecules are held together. If the intermolecular forces([van der Waals force][1]) are large, it means the molecules are tightly... |
The structure $\ce{H-H-O}$ does not technically exist in any common conditions because hydrogen does not generally form two covalent bonds at once. Such a structure would require a TON of energy to be put in because the hydrogen nucleus's lone proton would need to be able to hold electrons in the $2s$ sub level and pre... |
As was mentioned in the comments, with reference to the [Myers $\mathrm{p}K_{\mathrm{a}}$ table][1], the $\mathrm{p}K_{\mathrm{a}}$ values of a protonated ester and a protonated ketone are largely similar (in the region of $-7$ to $-6$).
Therefore, it will likely depend on external factors, which group is protonated... |
Following up on my comment, even though I'm not convinced that this is a 'real' answer to the question. Consulting the SGTE database of elemental free energies (AT Dinsdale, CALPHAD 15(4) 317-425 (1991) with various updates over the years), one can obtain the melting temperatures for the hcp, fcc, and bcc phases of Be... |
Is there a compound that can melt under its own weight? That is a block of such material remains solid when put horizontally but starts to melt when put vertically or remains solid in microgravity but melts in normal gravity?
The question is motivated by a documentary which I saw on TV some years ago where they clai... |
Are there compounds that melt under their own weight? |
Is there a compound that can melt under its own weight? That is, a block of such material remains solid when put horizontally but starts to melt when put vertically or remains solid in microgravity, but melts in normal gravity?
The question is motivated by a documentary which I saw on TV some years ago where they cl... |
The hydrogens in the structure you drew definitely should not be in the same environment — so while overlapping or close signals would be okay, the way your signals look isn’t. To get two signals to be identical, there needs to be some symmetrical way of corresponding the hydrogens to each other.
I can confirm a *tr... |
The first thing to note about the charges that form during the formation of a coordinate bond: They are a formality.
The second thing to note about the charges that form during the formation of a coordinate bond: **They are a mere formality.**
There is little correlation, if any at all, between the formal charges... |
How can I deduce the structure of my compound from this NMR spectra? |
I have not been able to get my head around it yet.
For instance in the reaction between ammonia and borontrifloride why is it that a positive and a negative charge results? Is it that ammonia donates is lone pair completely? If not so, if sharing of lone pair donated by ammonia occurs why then should charges result... |
Why do charges result on atoms when coordinate bonds are formed? |
Is it correct to say pyridine’s non-bonding electron pair does not participate in electron resonance while pyrrole’s non-bond electron participates in electron resonance? Would therefore pyridine’s resonance not be disturbed so act the molecule can act as a monodentate ligand? |
Already I know that hydrogen,all the halogens, nitrogen and oxygen forms diatomic molecules . But I am confused about Na? So I would like to know about that. |
Is it possible to have a diatomic molecule of sodium in gaseous state? |
Already I know that hydrogen, all the halogens, nitrogen and oxygen forms diatomic molecules. But I am confused about $\ce{Na}$? So I would like to know about that. |
I am currently learning chemical bonding, specifically Lewis structures. And these Nitrogen oxides, nitrogen-oxygen ions and other atoms showing variable oxidation states are confusing me. As many examples I have understood with bonding atoms having no d or f orbitals, the variable oxidation states are a result of dati... |
Are more than one correct Lewis structures possible (not counting resonance)? |
I am currently learning chemical bonding, specifically Lewis structures. And these nitrogen oxides, nitrogen-oxygen ions and other atoms showing variable oxidation states are confusing me. As many examples I have understood with bonding atoms having no $d$ or $f$ orbitals, the variable oxidation states are a result of ... |
I want to reduce Vanadyl to Vanadium (III), can somebody please suggest some appropriate methods for it? I am trying to make a redox flow battery for a project but I have only Vanadyl sulfate. |
I want to reduce vanadyl to vanadium (III), can somebody please suggest some appropriate methods for it? I am trying to make a redox flow battery for a project but I have only vanadyl sulfate. |
According to molecular orbital theory, disodium should be stable in the gas phase, with a bond order of one. The molecular orbital diagram is the same for all the alkali metals since they all have one valence electron in an $s$ orbital.
![enter image description here][1]
([image source][2])
NIST chemistry webb... |
Is a Racemic Mixture always an equi-molar solution of two enantiomers, both in the same state? Is it necessary for both the mixture to be liquid in nature, or does racemisation also occur in the gaseous or solid state?
Also, can the two enantiomers still form a Racemic mixture if they are initially at different tempera... |
> Is a Racemic Mixture always an equi-molar solution of two enantiomers, both in the same state?
Yes and yes. A *racemic* mixture is equimolar in both enantiomers. Otherwise you would call the reaction enantioselective with a so-and-so selectivity.
A racemic mixture contains both enantiomers in the same state, as ... |
Chlorine can be $sp^3d^3$ hybridised.
If so, it can form $\ce{ClH_7}$.In that case Chlorine, being more electronegative, will have (-7) as its oxidation #. But we know the minimum ox. # of $\ce{Cl}$ is (-1).
At which point am I going wrong? |
Is $\ce{ClH_7}$ possible? |
During racemisation enantiomers are mixed in a equal ratios to form an optically inactive mixture.
What type of reactions can take place between the enantiomers and how would this affect the mixture, if at all? |
Is ClH7 possible? |
Chlorine can be $sp^3d^3$ hybridized.
It can form $\ce{ClH_7}$ and chlorine, being more electronegative, will have (-7) as its oxidation number. But we know that the minimum oxidation number of $\ce{Cl}$ is (-1).
Can chlorine have different oxidation numbers depending on its chemical environment? |
After completing an experiment, a student finds that the percentage yield exceeded 100%. What could have occurred to the sample to lead to this? |
During racemization, enantiomers are mixed in a equal ratios to form an optically inactive mixture.
What type of reactions can take place between the enantiomers and how would this affect the mixture, if at all? |
According to molecular orbital theory, disodium should be stable in the gas phase, with a bond order of one. The molecular orbital diagram is the same for all the alkali metals since they all have one valence electron in an $s$ orbital.
![enter image description here][1]
([image source][2])
NIST chemistry webb... |
I have a really old sample of sodium tetraphenylborate. It should be white, but it is red. Does anyone know what was formed and how it influences precipitation of cations in water? |
Old, red sample of sodium tetraphenylborate—why it is red? |
As a follow up to [this][1] question I started thinking about another question. During racemization, enantiomers are mixed in a equal ratios to form an optically inactive mixture.
What type of reactions can take place between the enantiomers and how would this affect the mixture, if at all?
[1]: http://chemis... |
Are metallic/ionic bonds weaker than covalent bonds? |
Which elements can be diatomic and why?
---
**Motivation**
I shall discount the noble gases as they do not usually form bonds anyway. Looking at the non-metals.
Hydrogen, Nitrogen, Oxygen and the Halogens tend to be thermodynamically stable as a diatomic molecule at room temperature, and are usually labelle... |
Which elements can be diatomic? |
Which elements can be diatomic and why?
---
**Motivation**
<s>I shall discount the noble gases as they do not usually form bonds anyway. Looking at the non-metals.</s> See below.
Hydrogen, Nitrogen, Oxygen and the Halogens tend to be thermodynamically stable as a diatomic molecule at room temperature, and a... |
Which elements can be diatomic and why?
---
**Motivation**
<s>I shall discount the noble gases as they do not usually form bonds anyway. Looking at the non-metals.</s> See below.
Hydrogen, Nitrogen, Oxygen and the Halogens tend to be thermodynamically stable as a diatomic molecule at room temperature, and a... |
Preface: The problem is that you have *overstated your percentage yield*, and the symptom is that it is above 100%.
**Example:** You and your friend each do an experiment where the literature states the yield should be ~65%. You both use poor technique and fail to dry your product, causing you to attribute water mas... |
My chemistry book says, an electrophile is a reagent which is atrracted to electrons, therefore positive ions and reagents with incomplete octets act as electrophiles, Sulfur trioxide belongs to neither category, so how does it act as an electrophile? |
Why is Sulfur trioxide a neutral electrophile? |
I was researching and Googling and researching again, about this very interesting molecule: Diborane.
Then I faced a very interesting structure, something that I have never seen before. Something that turns up lesser than 50 results in Google, most of which are behind paywalls, and thus leave me in pain of not under... |
What's the bonding in diborane - hydrogen chloride? |
I was researching and Googling and researching again, about this very interesting molecule: Diborane.
Then I faced a very interesting structure, something that I have never seen before. Something that turns up lesser than 50 results in Google, most of which are behind paywalls, and thus leave me in pain of not under... |
What's the bonding in the diborane(6)- hydrogen chloride dimer? |
Reading the transcript of the Royal Society of Chemistry podcast [Helium Hydride][1], they state that helium hydride is possibly the most ancient compound to form in the Universe. They make the assertion that despite helium hydride being most stable as an ion, but:
> The neutral molecule can briefly exist, but only... |
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