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In this [video][1] on Khan Academy, Sal remarks that 'all atoms envy the noble gases, which are the most stable because they have eight electrons in their outer shell'.
I can't think of much of a reason that the number of electrons in the outer shell would affect the stability of the electron configuration. Additio... |
Why are electron configurations more stable when there are 8 electrons in the outer shell? |
In this [video][1] on Khan Academy, Sal remarks that 'all atoms envy the noble gases, which are the most stable because they have eight electrons in their outer shell'.
I can't think of much of a reason that the number of electrons in the outer shell would affect the stability of the electron configuration. Additio... |
What is the difference between *crystal radius* and *ionic radius*? For $\ce{NaCl}$ for example the ions combine to a crystal, and I would have guessed they are equal. But I then found an example of data, where they are not.
I am aware that [ionic radius][1] is the radius of an atom's ion. Quite simple. So what is *... |
To the best of my knowledge, the following properties affect atomic radius.
1. The grounded-state size of the valence electron shell.
2. The Coulomb force of the core electrons less the Coulomb force of the protons.
3. The number of electrons in the valence shell.
4. Whether an electron#-proton# imbalance i... |
The Henderson-Hasselbalch equation *is* independent of a buffer's level of dilution. However, *the equation itself is an approximation*, with a certain region of validity. In particular, it does not take into account the self-dissociation of water, which becomes increasingly more important in dilute solutions. This sug... |
Why are compounds of V5+ and Cr6+ colored? |
In this [video][1] on Khan Academy, Sal remarks that 'all atoms envy the noble gases, which are the most stable because they have eight electrons in their outer shell'.
I can't think of much of a reason that the number of electrons in the outer shell would affect the stability of the electron configuration. Additio... |
The Henderson-Hasselbalch equation *is* independent of a buffer's level of dilution. However, *the equation itself is an approximation*, with a certain region of validity. By its nature, it does not take into account the self-dissociation of water, which becomes increasingly more important in dilute solutions. This sug... |
For a much shorter and probably clearer explanation of this problem, look [here](http://www.chembuddy.com/?left=pH-calculation&right=pH-buffers-henderson-hasselbalch).
The Henderson-Hasselbalch (HH) equation *is* independent of a buffer's level of dilution. However, *the equation itself is an approximation*, with a ... |
For a much shorter and clearer explanation of this problem, look [here](http://www.chembuddy.com/?left=pH-calculation&right=pH-buffers-henderson-hasselbalch).
The Henderson-Hasselbalch (HH) equation *is* independent of a buffer's level of dilution. However, *the equation itself is an approximation*, with a certain r... |
For a much shorter and clearer explanation of this problem, look [here](http://www.chembuddy.com/?left=pH-calculation&right=pH-buffers-henderson-hasselbalch).
The Henderson-Hasselbalch (HH) equation is not to blame here. It is an approximate equation, with a certain region of validity. By its nature, it does not tak... |
The [other answer](http://chemistry.stackexchange.com/a/32234/5017) is, I think excellent.
Your question is basically "but what if there isn't a direct proportion between number of gas molecules and volume?" Instead, that was Avogadro's hypothesis in a nutshell: the volume of the gas is determined **exactly** propo... |
I'm a fairly inexperienced, but nonetheless interested chemist, currently planning a small project for the coming summer: I want to isolate an unknown chemical from a plant and determine it's chemical structure.
I have ample access to *Carex grayi*, a sedge plant, and have chosen this plant for a few reasons.
1... |
How can an inexperienced chemist determine the chemical structure of a molecule? |
I'm a fairly inexperienced, but nonetheless interested chemist, currently planning a small project for the coming summer: I want to isolate an unknown chemical from a plant and determine it's chemical structure.
I have ample access to *Carex grayi*, a sedge plant, and have chosen this plant for a few reasons.
1... |
Polymer Slurry used in boring foundation holes? |
**So, assuming I am able to extract an unknown chemical of some specified group from a plant, is there any way for me to determine the chemical's structure?**
Yes.
**I don't really have access to these tools as student over the summer. I am willing to spend a small amount of money on this project, but no more tha... |
what are the systems of recording atomic masses and their units?
I know that the nucleon number is the number of protons and neutrons
I also know that the mass number on the periodic table is the masses of all the isotopes and their relative abundance (I believe this is called relative atomic mass and is equal in... |
> Is there any extra force holding the two components together at that composition?
**Correct. Namely, hydrogen bonding.** As a quick refresher, hydrogen bonding is an electrostatic attraction between an electropositive hydrogen atom on one compound being (weakly) attracted to a highly elect... |
**So, assuming I am able to extract an unknown chemical of some specified group from a plant, is there any way for me to determine the chemical's structure?**
Yes.
**I don't really have access to these tools as student over the summer. I am willing to spend a small amount of money on this project, but no more tha... |
Any quantum number that represents the size of an orbital is a positive integer, $n$.
Any quantum number that represents the shape of an orbital is a non-negative integer, $l : l < n$.
Any quantum number that represents the orientation of an orbital, $m$, is an integer such that $|m| \leq l$.
Why do $n$ and $l$... |
I know that oxidanes are oxygen chains and rings. For example trioxidane is HO-O-OH. I can see this turning into O2 and H2O like hydrogen peroxide does. Since the double bonds in O2 are strong do oxygen compounds without nitrogen ever explode? |
Does oxygen ever explode? |
I know that oxidanes are oxygen chains and rings. For example trioxidane is $\ce{HO-O-OH}$. I can see this turning into $\ce{O2}$ and $\ce{H2O}$ like hydrogen peroxide does. Since the double bonds in $\ce{O2}$ are strong do oxygen compounds without nitrogen ever explode? |
If quenching is seen as a result of running electrochemical experiments on a solution, what kind of processes may be responsible? I'm thinking about UV/Vis spectroscopy, if it makes any difference.
The redox couple would be iodide ions, $\ce{I-/I^3-}$. I understand iodide ions to be quenching agents, so my suspicion... |
It is quite common to observe secondary peaks or "bumps" in the instrumental response function for a laser excitation. It is not always easy to pinpoint the origin of the second peak, but it is typically *not* associated with a reflection in the instrument. If any reflection were to be involved, it would be one within ... |
The normal technique for flame tests is to dip a clean nichrome or platinum wire into a solution of the relevant salt, and observe the resulting flame colour when inserting the wire into a non-luminous Bunsen flame.
But what is the species undergoing the electron transition that emits the light of characteristic fre... |
My teacher told me that Neon has a larger atomic radius than Fluorine.I am of the understanding that it is merely a consequence of the way we define the atomic radius and that we use Van der walls radius for neon which is larger that the covalent radius of fluorine.
He also said that the radius of a fluorine 1- ani... |
I would like to know how heat up a large amount of water ( assumption : 100 liter ) that people could use to take their bath and also it would not be dangerous even if they accidentally ingested it ? .
My idea is that to design a metal container and have the chemical in it . I'll react the chemical that is inside t... |
How the heat a large amount of water that is safe to use? |
The quantity **atomic mass** (quantity symbol: $m_\mathrm{a}$) is defined as rest mass of a neutral atom in the ground state.
The dimension of the atomic mass is
$$\dim m_\mathrm{a} = \mathsf{M}$$
The coherent SI unit for atomic mass is ‘kilogram’ (unit symbol: $\mathrm{kg}$).
The quantity **relative atomic m... |
OK
$\ce{NH_3}$ + HCl -> $\ce{NH_4Cl}$
Ammonia + Hydrochloric Acid -> Ammonium Chloride
The ammonia is bonded so that the N atom has an outer shell with a lone pair of electrons.
When they react, the hydrogen from the HCl moves to the ammonia, however it leaves its electrons behind because there is already ... |
OK
$\ce{NH_3 + HCl -> NH_4Cl}$
Ammonia + Hydrochloric Acid -> Ammonium Chloride
The ammonia is bonded so that the N atom has an outer shell with a lone pair of electrons.
When they react, the hydrogen from the $\ce{HCl}$ moves to the ammonia, however it leaves its electrons behind because there is already ... |
I'd like to ask a question and clear my misunderstanding.
>Which of the following 0,01 M solutions have the highest osmotic pressure?
>-$NaCl$
>-$C_{12}H_{22}O_{11}$
>-$BaCl_2$
>-$CO(NH_2)_2$
>-$[Cr(NH_3)_4Cl_2]Cl$
<hr>
I know that the equation for Osmotic pressure is
$π=CRTi$
I have eliminate... |
I’d like to ask a question and clear my misunderstanding.
>Which of the following 0.01 M solutions have the highest osmotic pressure?
>-$\ce{NaCl}$
>-$\ce{C12H22O11}$
>-$\ce{BaCl2}$
>-$\ce{CO(NH2)2}$
>-$\ce{[Cr(NH3)4Cl2]Cl}$
I know that the equation for osmotic pressure is
$$\Pi = cRTi$$
I have... |
This Indian Institute of Technology Bombay [press release][1] quotes some research papers which claims to prove that homeopathic remedies do retain original substances even when diluted.
> The paper reports the fascinating observation that certain high potency (highly diluted)
homeopathic remedies made from metals... |
Do extreme homeopathic dilutions still retain quantities of the starting materials? |
I'm getting a little confused about the definition of chelation and its implications (I should probably point out I'm only an A2 Chemistry student). The IUPAC defines chelation as "the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central atom... |
Are all complexes with a polydentate ligand examples of chelation? |
Cleaning an overhead water tank using Alum or other chemicals? |
Are ligand exchange reactions one-way reactions or reversible? I know this is a very silly question but its not said outright in any place...
For example, in my high school chemistry book, these two ligand exchange reactions are shown:
$$\ce{[Cu(H2O)6]^{2+} (aq) + 4Cl- (aq) <=> [CuCl_4]^{2-} (aq) + 6H2O (l)}$$
... |
Whats the difference between these contact process? |
I'm learning how to draw Lewis diagrams. Everything I've read emphasizes the octet rule. However, to the best of my knowledge, that rule only applies to elements in the first three periods.
On our exam, I expect our professor will ask us to draw some Lewis diagrams of molecules whose atoms do not comport with octet... |
What relatively simple molecule comprises atoms that comprise a great number of valence electrons? |
Which relatively simple molecules violate the octet rule? |
![][1]
[1]: https://i.stack.imgur.com/WbZOG.jpg
On seeing this graph closely I noticed the there a element with <b>no proton</b>. But with no proton there will be no electron too and don't think that an lone neutron would form an element. So is that given a half-life on neutron OR there exist a element (isoto... |
Element with No Proton? |
What is the difference between these equations for the Contact process? |
I'm learning how to draw Lewis diagrams. Everything I've read emphasizes the octet rule. However, to the best of my knowledge, that rule only applies to elements in the first three periods.
On our exam, I expect our professor will ask us to draw some Lewis diagrams of molecules whose atoms do not comport with the o... |
I am new to chemistry. For some of my homework (one of many problems), I was tasked with writing a molecular equation, an overall ionic equation, and a net ionic equation for the reaction between an aqueous solution of phosphoric acid, $\ce{H3PO4(aq)}$ and an aqueous solution of sodium hydroxide. The products are sodiu... |
In the picture below a proportionality equation is shown:
$$\omega \propto \nu \exp\left(\frac{-\Delta G_m}{RT}\right)\propto \dots$$
While $\Delta G_m$ is the Gibbs free energy, $R$ is the gas constant, and $T$ is the temperature, what are the parameters $\omega$ and $\nu$ exactly?
![enter image description h... |
What is $\omega$ and $\nu$ in this expression? |
What is omega and nu in this expression? |
In the [Kröger-Vink notation][1] the effective charge $c$ is marked as superscript while the site location $s$ is marked as subscript on the atom itself $A$:
$$A^c_s$$
As far as I have learned the effective charge is *the charge difference from the perfect lattice situation*. The Wikipedia definition agrees:
>... |
In the [Kröger-Vink notation][1] the effective charge $c$ is marked as superscript while the site location $s$ is marked as subscript on the atom itself $\ce{A}$:
$$\ce{A^{c}_{s}}$$
As far as I have learned the effective charge is *the charge difference from the perfect lattice situation*. The Wikipedia definitio... |
I actually tend to agree with the answer from @JanJensen based on electrostatic effects, rather than with the "covalency" argument.
In particular, it has been mentioned in the comments that the $\ce{Al^{III}-OH2}$ is a "far more covalent" bond than one $\ce{Mg^{II}-OH2}$ one. This remark, however, does not actually... |
- What is a non-classical carbocation?
- How is it different from a classical carbocation?
I am confused as I have come across this term many times on Chem.SE but there seems to be nothing for my level of understanding on the Internet! |
A paragraph in my text reads
> Bonding involves the valence orbitals almost exclusively because these orbitals have the appropriate energies to interact strongly. Examine the electron energy-level diagram of a fluorine atom. The core $1 \mathrm{s}$ orbitals on a fluorine atom are at much lower energies than any of t... |
My text seems to say that the high(est) energy orbitals are not valence orbitals - everything else says otherwise. What's true? |
I actually tend to agree with the answer from @JanJensen based on electrostatic effects, rather than with the "covalency" argument.
In particular, it has been mentioned in the comments that the $\ce{Al^{III}-OH2}$ is a "far more covalent" bond than one $\ce{Mg^{II}-OH2}$ one. This remark, however, does not actually... |
The [reaction rate equation][1] can be written as:
$$r=r_0 K \prod_n a_n$$
where the $a_n$s are the activities of each reactant in the reaction equation (in the case where we find the reaction rate **from reactants to products**, of course. Else the other way around). These activities are multiplied together. (Th... |
What is the "second-step" rate constant in the rate equation? |
What is the "rate factor" or "second-step rate constant" in the reaction rate equation? |
My text, and the other sources I've checked, include information on the effects, and kinds, of hybridized orbitals; however, they do not explain what causes them?
What causes orbital hybridization? |
Why causes orbital hybridization? |
How do I calculate the $\Delta H$ of the reaction where $2.6\:\mathrm{g}$ of water ($C_s= 4.184 \mathrm{\frac{J}{g\:K}}$) is heated, raising the temperature increases from $298\:\mathrm{K}$ to $303\:\mathrm{K}$? |
How to calculate the enthalpy change of water? |
> What causes orbital hybridization?
Hybridization only occurs in response to bond formation, that is an atom will not just spontaneously hybridize on its own. Further, **an atom will only hybridize if hybridization leads to the formation of a more stable (lower energy) molecule**.
Nature is very efficient at ... |
What causes orbital hybridization? |
My text, and the other sources I've checked, include information on the effects, and kinds, of hybridized orbitals; however, they do not explain what properties of hybridized bonds conduce greater stability.
Why does hybridization produce a (lower energy) more stable configuration? |
Why does hybridization produce a more stable configuration? |
What is the specific heat of a 20 g substance that releases 979 J of heat when changing from 70 degrees to 25 degrees
I started out with the following equation:
c=q/m*$\Delta T$
Q= 979J
M= 20g
$\Delta T$= 45 degrees
My final answer was 2202.75J
Did I use the right equation?
|
What is the specific heat of a 20 g substance that releases 979 J of heat when changing from 70 degrees to 25 degrees
I started out with the following equation:
$c = \frac{q}{m\Delta T}$
Q= 979J
M= 20g
$\Delta T$= 45 degrees
My final answer was 2202.75J
Did I use the right equation?
|
How to rationalise the IUPAC name for tetrahedrane? |
This problem is a tough one imo. The Kb for C5H5N and C5H5NH+ is 1.7*10^-9. This problem is asking you to solve for pH though. Here's my work, but it's wrong (at least I tried):
C5H5NHF --> C5H5NH+ + F- Ka for HF= 4.0*10^-4
K=Kw/Ka --> K=1*10^-14/4.0*10^-4=2.5*10^-11
Construct an ice table:
F-..... + H20(l) .... |
This problem is a tough one. The Kb for C5H5N and C5H5NH+ is 1.7*10^-9. This problem is asking you to solve for pH though. Here's my work, but it's wrong (at least I tried):
C5H5NHF --> C5H5NH+ + F- Ka for HF= 4.0*10^-4
K=Kw/Ka --> K=1*10^-14/4.0*10^-4=2.5*10^-11
Construct an ice table:
F-..... + H20(l) .... ... |
How to calculate the $\mathrm{pH}$ of a $0.325~\mathrm{M}$ solution of $\ce{C5H5NHF}$? The $K_\mathrm{b}$ for $\ce{C5H5N}$ and $\ce{C5H5NH+}$ is $1.7\cdot10^{-9}$.
Here's my work, but it's wrong (at least I tried):
$$\ce{C5H5NHF -> C5H5NH+ + F- }$$
$$K_\mathrm{a}(\ce{HF})= 4.0\cdot10^{-4}$$
$$K=\frac{K_\mathrm... |
How to calculate the pH of a 0.325 M solution of C5H5NHF? |
Why is 4-ethyl-1-fluoro-2-nitrobenzene (structure is in the attached picture) called so ?
Shouldn't it be called as 1-ethyl-4-fluoro-3-nitrobenzene since the *precedence of ethyl is greater than halogens*?
![4-ethyl-1-fluoro-2-nitrobenzene][1]
[1]: https://i.stack.imgur.com/QsRCVm.png |
How do I calculate the $\Delta H$ of the reaction where $2.6\:\mathrm{g}$ of water ($C_s= 4.184 \mathrm{\frac{J}{g\:K}}$) is heated, raising the temperature increases from $298\:\mathrm{K}$ to $303\:\mathrm{K}$?
I used the following equation: $\Delta H$=M$\times C$$\times \Delta$T
M= 2.6g
C= 4.184 J/G
$\Del... |
There are two proposed mechanisms for this.
The first one is the attack of the pi-bond on the $\ce{Hg(OAc)2}$.
But why does mercuric acetate acts an electrophile here? It is in its most common +2 oxidation state. Does this happen only because mercury has empty $6d$ orbitals.
While the second mechanism states t... |
How do I calculate the $\Delta H$ of the reaction where $2.6\:\mathrm{g}$ of water ($C_s= 4.184 \mathrm{\frac{J}{g\:K}}$) is heated, raising the temperature increases from $298\:\mathrm{K}$ to $303\:\mathrm{K}$?
|
How do I calculate the $\Delta H$ of the reaction where $2.6\:\mathrm{g}$ of water ($C_s= 4.184 \mathrm{\frac{J}{g\:K}}$) is heated, raising the temperature increases from $298\:\mathrm{K}$ to $303\:\mathrm{K}$?
I used the following equation: $\Delta H$=M$\times C$$\times \Delta$T
M= 2.6g
C= 4.184 J/G
$\Del... |
What is the specific heat of a 20 g substance that releases 979 J of heat when changing from 70 degrees to 25 degrees
I started out with the following equation:
$c = \frac{q}{m\Delta T}$
Q= 979J
M= 20g
$\Delta T$= 45 degrees
My final answer was 2202.75J
Did I use the right equation?
|
How do I calculate the $\Delta H$ of the reaction where $2.6\:\mathrm{g}$ of water, $C_s= 4.184 \mathrm{\frac{J}{g\:K}}$ is heated, raising the temperature increases from $298\:\mathrm{K}$ to $303\:\mathrm{K}$?
I used the following equation: $\Delta H=M \cdot C\cdot \Delta T$
$M = 2.6~\mathrm{g}$, $C = 4.184~\mat... |
Let $R$ be the orthogonal matrix corresponding to an operation in $O(3)$. If
R is a proper rotation, then both vectors $\vec{V}$ and axial vectors $\vec{A}$ are transformed in the same way
$$ \vec{V} \rightarrow \vec{V}' = R\vec{V}$$
$$ \vec{A} \rightarrow \vec{A}' = R\vec{A}$$
if $R$ is an improper rotations... |
According to the [Online Etymology Dictionary][1], the word **bicarbonate** is derived as follows:
> 1814, bi-carbonate of potash, apparently coined by English chemist William Hyde Wollaston (1766-1828), from bi- + carbonate.
The question then becomes, what is the meaning of the prefix **bi-** here? We know it m... |
Let $R$ be the orthogonal matrix corresponding to an operation in $O(3)$. If
R is a proper rotation, then both vectors $\vec{V}$ and axial vectors $\vec{A}$ are transformed in the same way
$$ \vec{V} \rightarrow \vec{V}' = R\vec{V}$$
$$ \vec{A} \rightarrow \vec{A}' = R\vec{A}$$
if $R$ is an improper rotations... |
How to perform oxidation of keto group in presence of hydroxyl group. I fear there may be halogenation at OH group. is there a way to protect the OH group ? |
The $\mathrm{d}$-block sub-shell is always one shell lower than the $\mathrm{s}$-block and $\mathrm{p}$-block sub-shells. Assuming only the electrons in the highest energy shells count toward the set of valence electrons (is that correct?), $\mathrm{d}$-block is never in the highest energy shell, and so none of the ele... |
1) I can understand that we need to supply energy to counter the nuclear attraction when we remove electrons and that is the reason ionisation energy is endothermic.
But why does the atom have to release energy when we add an electron to it?
2) And also the book says that elements like Be have positive or zero ele... |
Why is electron gain generally exothermic? |
How to perform oxidation of keto group in presence of hydroxyl group. I fear there may be halogenation at $\ce{OH}$ group. Is there a way to protect the $\ce{OH}$ group ? |
How to perform oxidation of keto group in presence of hydroxyl group? |
1) I can understand that we need to supply energy to counter the nuclear attraction when we remove electrons and that is the reason ionisation energy is endothermic.
But why does the atom have to release energy when we add an electron to it?
2) Coming to ionisation energy, why do we need to supply energy to remove... |
We dissolve $10g$ of $CuCl_2$ in $0,1L$ of watter
Given that :
$M(Cl)=35,5g/mol$
$M(Cu)=63,5g/mol$
How can one calculate the molar concentration of $Cu^{2+}$ and $Cl^{-1}$ ?
First of all I calculated the the quantity of matter of $CuCl_2$ :
$n(CuCl_2)=0,074mol$
The the molar concentration :
$C=\frac{0,074}{01}=0... |
1) I can understand that we need to supply energy to counter the nuclear attraction when we remove electrons and that is the reason ionisation energy is endothermic.
But why does the atom have to release energy when we add an electron to it?
2) Coming to ionisation energy, why do we need to supply energy to remove... |
We dissolve $10\ \mathrm{g}$ of $\ce{CuCl2}$ in $0.1\ \mathrm{L}$ of water.
Given that:
$M(\ce{Cl})=35.5\ \mathrm{g/mol}$
$M(\ce{Cu})=63.5\ \mathrm{g/mol}$
How can one calculate the molar concentration of $\ce{Cu^2+}$ and $\ce{Cl-}$?
First of all I calculated the the quantity of matter of $\ce{CuCl2}$ :
... |
We dissolve $10\ \mathrm{g}$ of $\ce{CuCl2}$ in $0.1\ \mathrm{L}$ of water.
Given that:
$M(\ce{Cl})=35.5\ \mathrm{g/mol}$
$M(\ce{Cu})=63.5\ \mathrm{g/mol}$
How can one calculate the molar concentration of $\ce{Cu^2+}$ and $\ce{Cl-}$?
First of all I calculated the the quantity of matter of $\ce{CuCl2}$:
... |
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