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What is a pure substance? |
I love Kleenex Cool Touch tissues. I'm just wondering what makes them actually feel cool. For some reason it makes me think of refrigerant but I'm sure that's not in them. Is it the combination of common ingredients that somehow gives it a moist feel, making it feel cooler than normal tissues? And are the tissues s... |
What makes Kleenex Cool Touch tissues cool to the touch, and is it safe? |
I am looking for the precise definitions, as I am very confused as to what they are exactly, because although I mostly understand what they mean, I have encountered some conflicting definitions that confused me.
As it stands, this is what I understand them to mean:
- Compound: two or more different atoms bonded... |
What is the definition of of 'compound', 'mixture', 'element' and 'molecule'? |
In a sample of water, you'll find the **compound** $H_2O$. In a sample of hydrogen gas, you'll find the **element** hydrogen, though it'll take the form of the **molecule** $H_2$. In a mixture, you may find different **molecules**, **compounds**, and **elements**.
Does this genearlly clean up your understandings? |
In a sample of water, you'll find the **compound** $H_2O$. In a sample of hydrogen gas, you'll find the **element** hydrogen, though it'll take the form of the **molecule** $H_2$. In a mixture, you may find different **molecules**, **compounds**, and **elements**.
At this point, you may find it helpful to look at th... |
What is the difference between thermodynamic and kinetic stability? I'd like a basic explanation, but not too simple. For example, methane does not burn until lit -- why? |
I love Kleenex Cool Touch tissues. I'm just wondering what makes them actually feel cool. For some reason it makes me think of refrigerant but I'm sure that's not in them.
Is it the combination of common ingredients that somehow gives it a moist feel, making it feel cooler than normal tissues?
Are the tissu... |
For example Magnesium has a higher charge density compared to Sodium therefore its Metallic lattice is stronger and so it has a higher melting point. Does it mean Magnesium has more protons, smaller atomic radius or is it about its charge (2+), that makes its lattice stronger?
What does charge density show? |
For example, Magnesium has a higher charge density compared to Sodium, therefore its metallic lattice is stronger and it has a higher melting point. Does that mean that Magnesium has more protons and a smaller atomic radius or is it about its charge (2+), that makes its lattice stronger?
What does charge density sho... |
What is charge density? |
If it was about the number of protons in the nucleus then Mercury could hardly be liquid at room temperature according to this reason, could it?
No, it is in fact about the density of _free electrons_, i.e. the density of the "electron gas" that makes up the [metallic bonding](http://en.wikipedia.org/wiki/Metallic_b... |
>If it was about the number of protons in the nucleus then Mercury could hardly be liquid at room temperature according to this reason, could it?
No, it is in fact about the density of _free electrons_, i.e. the density of the "electron gas" that makes up the [metallic bonding](http://en.wikipedia.org/wiki/Metallic_... |
If it was about the number of protons in the nucleus then Mercury could hardly be liquid at room temperature according to this reason, could it?
No, it is in fact about the density of _free electrons_, i.e. the density of the "electron gas" that makes up the [metallic bonding](http://en.wikipedia.org/wiki/Metallic_b... |
If it was about the number of protons in the nucleus, then Mercury would hardly be liquid at room temperature, would it?
Actually, it is about the density of _free electrons_, i.e. the density of the "electron gas" that makes up the [metallic bonding](http://en.wikipedia.org/wiki/Metallic_bonding). Obviously, this d... |
I saw in the chernobyl documantary, it was saying, uranium should not contact with water, otherwise an explosion occurs. what is the reason for that? What kind of reaction make it explode? |
why uranium should not contact with water? |
In the documentary about Chernobyl, it was mentioned that Uranium should not come in contact with water, otherwise an explosion occurs. What is the reason for that? What kind of reaction makes it explode? |
Why shouldn't Uranium come in contact with water? |
"Why" is a good question, and one that science has yet to fully answer. We generally have a good understanding of "how" things work at the subatomic level, based on over a century of observation followed by theory and math backed up by experimentation. However, the really basic, naively simple questions, like "where do... |
Using a molecular viewer like PyMOL, I understand that its often incorrect to simply look at positive and negative residues and use those residues to calculate the charge density and instead, you should be using something like APBS to calculate the electrostatic potential. What is the correct way of going about to do t... |
Another possible explanation: water [can act as a neutron reflector](http://www.researchgate.net/post/Can_anyone_suggest_a_good_neutron_reflecting_material), at least under some conditions. Therefore, it might be possible for a subcritical mass of uranium to become supercritical if immersed in water, as some of the em... |
Using a molecular viewer like PyMOL, I understand that its often incorrect to simply look at positive and negative residues and use those residues to calculate the charge density and instead, you should be using something like APBS to calculate the electrostatic potential.
What is the correct way of going about thi... |
What is the appropriate method to visualize electrostatic potentials? |
First, is this a question from your book, and do you have the correct answer to check your work.
Do you know how to use dimensional analysis?
Start with 50 mL. You have 2 Molarity of some subtance, how do you write that as a quotient and what are the units of the denominator and numerator? You will also need to k... |
What is the chemical structure of H₂SO₄? |
I am reading a paper[1] that contains the line:
> Most of the $\small H_2$ in the Earth's mantle escaped to space early in the Earth's history; consequently, the overwhelming majority of the abiotic geochemical reactions are based on acid/base chemistry, i.e., transfers of protons without electrons.
The connectio... |
Why would the loss of H₂ to space mean that the Earth's geochemistry would be based on acid/base reactions? |
Does Hund's rule allow both of the following scenarios?
- Filling each orbital with a single electron, so that a sub-shell, at first, only electrons with a negative spin
- Filling each orbital with a single electron, such tha ta sub-shell, at first, only electrons with a positive spin?
I assume two H atoms who... |
In a simple reaction between butane and chlorine, it is more likely for the secondary carbons of the butane to lose a hydrogen and gain a chlorine. The carbocation is a more stable intermediate in that situation compared to a primary carbon losing the hydrogen. So if the desired synthesis is 1-chlorobutane as opposed t... |
Is it more reasonable to use stratification to separate similar compounds rather than using temperature? |
Does Hund's rule allow both of the following scenarios?
- Filling each orbital with a single electron, so that a sub-shell, at first, only electrons with a negative spin
- Filling each orbital with a single electron, such that a sub-shell, at first, only electrons with a positive spin?
I assume two H atoms who... |
I'm reading about electrodeposition of conductive polymers in a chemistry textbook, and the author mentions 'trace-crossing' in the 'potentiodynamic response'. From the context I can figure out that 'potentiodynamic response' means cyclic voltammogram. But what is the 'trace crossing'? |
What is a 'Trace Crossing'? |
What is a "lagged bath"? |
The equation for the reaction between a [permanganate][1] and iron(II) ions in **acidic** solution is:
$\text{MnO}_4^- + \text{Fe}^{2+} \longrightarrow \text{Fe}^{3+} + \text{Mn}^{2+}$
My book, as well as a certain [equation balancer][2], shows that the answer is:
$5\text{Fe}^{2+} + \text{MnO}_4^- 8\text H^+ ... |
Can you tell me whats the nomenclature of CH2O2?
Can you Please tell me its IUPAC NAME
THANKS IN ADVANCE |
Can you tell me whats the nomenclature of CH2O2? |
Alanin and dyes contain nitrogen ,
is there special feature in nitrogenous substances? |
Why nitrogenous hydrocarbons are colorful? |
Introduction from [Color Introduction][1]
"What causes a compound to appear as being colored? The answer to this question lies in the way that electromagnetic energy interacts with matter. The portion of the electromagnetic spectrum that is of interest to this discussion is the visible portion, or what we call light... |
Can you tell me whats the nomenclature of $\ce{C H_2 O_2}$?
Can you Please tell me its IUPAC NAME?
|
Can you tell me what's the nomenclature of $\ce{C H_2 O_2}$?
What is its IUPAC name?
|
Alanin and dyes contain nitrogen, is being colorful a special feature in nitrogenous substances? |
Why are nitrogenous hydrocarbons sometimes colorful? |
Introduction from [Color Introduction][1]
>"What causes a compound to appear as being colored? The answer to this question lies in the way that electromagnetic energy interacts with matter. The portion of the electromagnetic spectrum that is of interest to this discussion is the visible portion, or what we call ligh... |
What is the proper nomenclature for C₂HO₂? |
What is the proper nomenclature for CH₂O₂? |
Is it possible, chemically, to change a dextrorotatory compound to its levorotatory counterpart? e.g. Is it possible to change levodopa to dextrodopa? |
Is it Possible, Chemically, to change a Dextrorotatory Compound to its Levorotatory Counterpart? |
I'm tutoring few Class 12 students for their chemistry exams. I'm stuck with few problems. I don't know, if the key is wrong or I am wrong.
**Problem:**
![enter image description here][1]
**Answer According to me:**
> Must be (A) because that's wurtz reaction.
**Answer given in the book:**
> (B)
How... |
What will be major product of wurtz reaction? |
I'm tutoring few Class 12 students for their chemistry exams. I'm stuck with few problems. I don't know, if the key is wrong or I am wrong.
**Problem:**
![enter image description here][1]
**Answer According to me:**
> Product (A) must be the cyclic diene, as given in option (A). Now, I don't know, what hap... |
What will be the product? |
I'm tutoring few Class 12 students for their chemistry exams. I'm stuck with few problems. I don't know, if the key is wrong or I am wrong.
**Problem:**
![enter image description here][1]
**Answer According to me:**
> According to me, both the left side and the right side double bonds undergo cleavage and ... |
What will be the Ozonolysis product? |
Alkynes are more reactive towards catalytic hydrogenation than that of alkenes, because they are more unsaturated. [kindly, tell me if these is not the correct reason.].
But how come carbonyl compunds are more reactive towards catalytic hydrogenation than alkyenes? The `C=O` in carbonyl group is polar, but how does ... |
Why carbonyl compunds are more reactive towards catalytic hydrogenation than alkynes and alkenes? |
I'm tutoring few Class 12 students for their chemistry exams. I'm stuck with few problems. I don't know, if the key is wrong or I am wrong.
**Problem:**
![enter image description here][1]
**My comments:**
> **Option (A):** Conc. H2SO4, is an acid, it gives $H^+$ ions which must act like electrophile and ... |
What would be the mechanism of the given reaction? |
What will be the major product of this Wurtz reaction? |
Any reaction in general will try to attain maximum possible stability.
The reactivity of a molecule or a group is inversely proportional to its stability.
The general order of reactivity of carbonyl compounds is as follows:
$$\small\ce{Aldehyde > Ketone > Acid halide > Anhydride > Ester > Carboxylic Acid > Ac... |
Alkynes are more reactive towards catalytic hydrogenation than that of alkenes, because they are more unsaturated. [kindly, tell me if these is not the correct reason.].
But why are carbonyl compunds more reactive towards catalytic hydrogenation than alkyenes? The $\ce{C=O}$ in carbonyl group is polar, but how does ... |
I'm tutoring few Class 12 students for their chemistry exams. I'm stuck with few problems. I don't know if the key is wrong or I am wrong.
**Problem:**
![enter image description here][1]
**My comments:**
> **Option (A):** Conc. $\ce{H2SO4}$, is an acid, it gives $H^+$ ions which must act like electrophil... |
Bottom line: $\ce{HSO4-}$ is a really bad nucleophile, and it doesn't enter in the picture.
![enter image description here][1]
(I realize after scanning that I'm missing the "+ H<sup>+</sup>" alongside the final product.)
---
Question for extra credit: after the second step, why is the third step (carbocat... |
If I understand correctly, H<sub>2</sub> in the presence of Pd readily dissociates as it dissolves into the metal. With the dissociation energy for the H—H bond being so large, how is this possible?
At first I thought that the H atoms were falling to a lower energy level in the Pd that was somehow only available if... |
I am going to stick a strain gauge to the side of an expanding piezocrystal using a basic 2 part epoxy glue. I am eventually also going to be sticking other things to it. Does anyone know a safe way to remove the glue without damaging the piezostack? The manual says specifically not to use acetone.
|
Unfortunately the aufbau rule cannot predict all electron configuration as it doesn't take into account electron-electron interactions. in the end the aufbau is only a rule of thumb. Electronic levels have to be found using quantum calculations taking into account electron-electron interactions (not to mention spin orb... |
Unfortunately, the Aufbau rule cannot predict all electron configuration as it doesn't take into account electron-electron interactions. In the end the Aufbau is only a rule of thumb. Electronic levels have to be found using quantum calculations taking into account electron-electron interactions (not to mention spin or... |
I have two questions:
1. To find the parent chain of a saturated hydrocarbon, we have to find the longest chain and then if we have a choice, we choose the one with the more substituents. But what if we still had a choice? What would we do next?
2. If an alkyl substituent is attached to the parent chain by a doub... |
I have three questions:
1. To find the parent chain of a saturated hydrocarbon, we have to find the longest chain and then if we have a choice, we choose the one with the more substituents. But what if we still had a choice? What would we do next?
2. Similarly, for numbering the chain, the last step is to numbe... |
I have three questions:
1. To find the parent chain of a saturated hydrocarbon, we have to find the longest chain and then if we have a choice, we choose the one with the more substituents. But what if we still had a choice? What would we do next?
2. Similarly, for numbering the chain, the last step is to numbe... |
I have three questions:
1. To find the parent chain of a saturated hydrocarbon, we have to find the longest chain and then if we have a choice, we choose the one with the more substituents. But what if we still had a choice? What would we do next?
2. Similarly, for numbering the chain, the last step is to numbe... |
I have three questions:
1. To find the parent chain of a saturated hydrocarbon, we have to find the longest chain and then if we have a choice, we choose the one with the more substituents. But what if we still had a choice? What would we do next?
2. Similarly, for numbering the chain, the last step is to numbe... |
I have three questions:
1. To find the parent chain of a saturated hydrocarbon, we have to find the longest chain and then if we have a choice, we choose the one with the more substituents. But what if we still had a choice? What would we do next?
2. Similarly, for numbering the chain, the last step is to numbe... |
How do you create primary amines from alcohols? |
I have three questions:
1. To find the parent chain of a saturated hydrocarbon, we have to find the longest chain and then if we have a choice, we choose the one with the more substituents. But what if we still had a choice? What would we do next?
2. Similarly, for numbering the chain, the last step is to numbe... |
Why is the Electronegativity difference for atoms in bonding to determine what the compound will likely be uncertain? According to the IB they say that the Electronegativity difference required for Ionic bonds is 1.7 though compounds like Hydrogen Fluoride are covalent even though they have a Electronegativity differe... |
Is chemical energy basically stored energy?
I'm not sure how to define "chemical energy" while I know many physical formulas for energy e.g. potential, movement and other.
Is chemical energy an energy that is "conserved" and if so, why is chemical energy not just potential energy?
What's the point of many diff... |
How to know chemical energy from physical energy? |
Is chemical energy basically stored energy?
I'm not sure how to define "chemical energy" while I know many physical formulas for energy e.g. potential, movement and other.
Is chemical energy an energy that is "conserved" and if so, why is chemical energy not just potential energy?
What's the point of many diff... |
Is chemical energy basically stored energy?
I'm not sure how to define "chemical energy" while I know many physical formulas for energy e.g. potential, movement and other.
Is chemical energy an energy that is "conserved" and if so, why is chemical energy not just potential energy?
What's the point of many diff... |
Is chemical energy basically stored energy?
I'm not sure how to define "chemical energy" while I know many physical formulas for energy e.g. potential, movement and other.
Is chemical energy an energy that is "conserved" and if so, why is chemical energy not just potential energy?
Additional questions:
*... |
What is the nature of chemical energy? |
Why is the Electronegativity difference for atoms in bonding uncertain while determining what the compound will be?
According to the IB they say that the Electronegativity difference required for Ionic bonds is 1.7 though compounds like Hydrogen Fluoride are covalent even though they have a Electronegativity differe... |
As mentioned in the comments, _why not_? A boron-boron bond will form as long as there is an increase in stability of the system. Forming a bond requires energy, but there is a lot of energy released once it gets formed. The feasibility of a bond depends which energy is greater.
One example of where a boron-boron bo... |
Watching some movie/TV this question came to mind, purely theoretical of course, if one wanted to dissolve a human corpse, like getting rid of a body after killing someone, is it better to use an acid or a base? In the movies (as well the popular perception for some reason) they always use acid. The movie I was watchin... |
As mentioned in the comments, _why not_? A boron-boron bond will form as long as there is an increase in stability of the system. Forming a bond requires energy, but there is a lot of energy released once it gets formed. The feasibility of a bond depends which energy is greater.
One example of where a boron-boron bo... |
Why is the Electronegativity difference for atoms in bonding uncertain while determining what the compound will be?
According to the IB(International Baccalaureate) they say that the Electronegativity difference required for Ionic bonds is 1.7 though compounds like Hydrogen Fluoride are covalent even though they hav... |
Why is the Electronegativity difference for atoms in bonding uncertain while determining what the compound will be?
According to the IB(International Baccalaureate) they say that the Electronegativity difference required for Ionic bonds is 1.7 though compounds like Hydrogen Fluoride are covalent even though they hav... |
Why is the Electronegativity difference for atoms in bonding uncertain while determining what the compound will be?
According to the IB(International Baccalaureate) they say that the Electronegativity difference required for Ionic bonds is 1.7 though compounds like Hydrogen Fluoride are covalent even though they hav... |
Why is the Electronegativity difference for atoms in bonding uncertain while determining what the compound will be?
According to the IB(International Baccalaureate) they say that the Electronegativity difference required for Ionic bonds is 1.7 though compounds like Hydrogen Fluoride are covalent even though they hav... |
I was reading [MECHANISM OF α-HALOGENATION OF ALDEHYDES AND KETONES][1]:
![enter image description here][2]
As you can see in the third step. Bromide ion is picking up a base from protonated acetone. Doesn't that step mean that protonated acetone is stronger acid than Hydrobromic acid? Is that even possible?
... |
Can bromide ion ever act like a base? |
What will be the product when 1,3-cyclohexadiene is heated with selinium? |
Chemical energy is really nothing but electric potential energy.
The crucial difference is that chemical energy involves energy that can be extracted by breaking/making bonds.
For example, we say that the reaction $\ce{2H2 + O2->H2O}$ is accompanied by a release of energy. This energy is the difference of potenti... |
Come on, you can figure out this one on your own! How do you compare acidities? [Here's a helpful hint](http://cactus.dixie.edu/smblack/chem2310/summary_pages/pKa_chart.pdf).
Armed with that information, I have to add something. I believe the mechanism as drawn above is not universal: it sure depends on the conditio... |
I apologize for this question. It is probably ill posed and silly. But I was thinking back to my chemistry major days and remembering the bunch of cool spectra we produced by various means (HNMR, IR, UV/Vis) and I remember all the cool 'self-interference' like couplets, triplets doublets, etc.
My question is basica... |
fourier transform for spectroscopy spectra? |
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