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Why is the increase in covalent radius from As to Bi not as big as from N to P? |
I don't think that any realistic modeling is possible. There are a lot of details which would made such a system chaotic. For the liquid side of the gas/liquid system consider the differences in evaporating from a thin layer in a very large diameter vessel to evaporation from a extremely long tube of the mixture.
F... |
I think, what actually OP meant to ask is:
>Are there any known organic compounds with carbon involving in an ionic bond?
The reason for my suggestion is the phrase "to make an ionic bond and to exhibit ionic properties" in OP's question, even though it did not describe the involvement of carbon. Otherwise, any i... |
In S<sub>N</sub>1 reactions, it's known that there are generally two steps, with the first being the R.D.S step involving carbocation formation and the next having a lower activation energy.
Why does the second step require activation energy at all? It's going from being a carbocation to a stable molecule, which wil... |
> Oxidation numbers are fictitious charges that pretend the entire molecule is an ion i.e. it artificially localizes electrons onto atoms within a single molecule.
Sort of. In calculating oxidation numbers we pretend that covalent bonds are ionic. Perhaps it is valid to say we are pretending the entire molecule is a... |
The following is the radius of Group $15$ elements:
$$\begin{array}{c|c} \hline
\text{Element} & \text{Covalent Radius }(\pu{pm}) \\ \hline
\ce{N} &75 \\
\ce{P} &110 \\
\ce{As} &121 \\
\ce{Sb} &140 \\
\ce{Bi} &155 \\ \hline
\end{array}$$
Source:
General Properties and Reactions. (2020, August 15). Ret... |
Why do green bell peppers taste sweet raw, but become bitter when cooked (steamed)?
What chemical process is responsible for this? |
Why do green bell peppers become bitter when cooked? |
Why do green bell peppers taste sweet raw, but become bitter when cooked (steamed)?
What chemical process is responsible for this? (I don't believe the temperatures are high enough for the Maillard reaction)
---
Please explain the downvote(s). I wondered if this might be off-topic, but since [tag:food-chemistry]... |
Very basic question here, but I'm confused why Delta-H seems to be the reverse of what I would expect for bond enthalpy. For example, here's a problem in my textbook where the goal is to find delta-H:
H2(g) + Br2(l) -> 2Hbr(g)
Using the table I have, I see that an H-H bond has an average enthalpy of 436, Br-Br ha... |
Why is delta-H negative here? |
The relative entropies of two substances at a temperature $T'$ are not determined by their relative heat capacities at $T'$. Rather,
$\text {Absolute entropy at } T' \equiv S(T') =\Delta S_{0 \rightarrow T'}= \int_{0}^{T'}\frac{\text{đ}q_{rev}}{T} = \int_{0}^{T'}\frac{C_p(T)}{T} dT$
I.e., for each substance, y... |
The relative entropies of two substances at a temperature $T'$ are not determined by their relative heat capacities at $T'$. Rather,
$$\text {Absolute entropy at } T' \equiv S(T') =\Delta S_{0 \rightarrow T'}$$
$$= \int_{0}^{T'}\frac{\text{đ}q_{rev}}{T} = \int_{0}^{T'}\frac{C_p(T)}{T} dT.$$
I.e., for each sub... |
The relative entropies of two substances at a temperature $T'$ are not determined by their relative heat capacities at $T'$. Rather,
$$\text {Absolute entropy at } T' \equiv S(T') =\Delta S_{0 \rightarrow T'}$$
$$= \int_{0}^{T'}\frac{\text{đ}q_{rev}}{T} = \int_{0}^{T'}\frac{C_p(T)}{T} dT.$$
I.e., for each sub... |
Very basic question here, but I'm confused why Delta-H seems to be the reverse of what I would expect for bond enthalpy. For example, here's a problem in my textbook where the goal is to find delta-H:
$$\ce{H2(g) + Br2(l) -> 2HBr(g)}$$
Using the table I have, I see that an $\ce{H-H}$ bond has an average enthalpy ... |
I have found Urtz reaction for primary alkyl halide in my textbook. My textbook also says that only primary and secondary alkyl halide shows Urtz reaction and tertiary alkyl halides doesn't show Urtz reaction. I tried to write the Urtz reaction for secondary alkyl halide which is not included in my textbook. I think th... |
Thousands of different chemicals, previously spatial separated, are mixed together after thermal death of cells, and kept at high temperature to react well. Final taste will depend on original system, but will develop by way unpredictable theoretically from basic principles.
The answer for a particular biological s... |
Thousands of different chemicals, previously spatial separated, are mixed together after thermal death of cells, and kept at high temperature to react well. Final taste will depend on original system, but will develop by way unpredictable theoretically from basic principles.
The answer for a particular biological s... |
I will elaborate on my question here.
In my Lecture Notes it is mentioned that for methane, there are 4 different $\text{C-H}$ bond energies. I plotted a quick graph of the bond energies to analyse the trend.
[![enter image description here][1]][1]
Here the vertical axis represents the bond dissociation ene... |
Why does methane have 4-different bond dissociation energies? |
I have found Wurtz reaction for primary alkyl halide in my textbook. My textbook also says that only primary and secondary alkyl halide shows Wurtz reaction and tertiary alkyl halides doesn't show Wurtz reaction. I tried to write the Wurtz reaction for secondary alkyl halide which is not included in my textbook. I thin... |
Thousands of different chemicals, previously spatial separated, are mixed together after thermal death of cells, and kept at high temperature to react well. Final taste will depend on original system, but will develop by way unpredictable theoretically from basic principles.
The answer for a particular biological s... |
Welcome to ChemistrySE.
In short: is the spectrum consistent with 3-methyl-1-butanol? No. The triplet splitting and integral of the signal at 0.86ppm is inconsistent with an isopropyl sidechain. This suggests a methyl group attached to a methylene, $\ce{-CH2-CH3}$.
The signal at $\pu{3.6 ppm}$ has a chemical shi... |
The molar heat capacity of hydrogen gas and deuterium gas are nearly the same, $\pu{28.8 J/K mol}$ and $\pu{29.2 J/K mol}$ respectively, but the absolute entropy of deuterium ($\pu{145.0 J/K mol}$) is significantly larger than hydrogen's ($\pu{130.7 J/K mol}$).
I have seen the equation that associates the heat capa... |
In the aquation of cis-platin, why are the chloride ligands, and not ammonia, replaced with water, despite chloride's larger trans effect? |
Every explanation I can find says something like: valence electrons in metals have low ionising energies and non-metals ''want'' to complete their valence shell.
But I can't seem to get my head around the ''wants to complete it's valence shell'' force.
Take a neutral sodium atom and a neutral chlorine atom separa... |
What force causes an electron to jump from say Na to Cl? |
>Why does the open circuit voltage of a battery decrease with increase in $\mathrm{pH}$ of electrolyte, but the voltage across a load increase?
I tested a cell which had aluminum sulfate as its anode electrolyte ($\pu{12 g}$ aluminum in $\pu{50 mL}$ water and a $\mathrm{pH}$ of 3.2), and potassium hydroxide as the c... |
The open circuit voltage of a battery: Does it decrease with increase in pH of electrolyte while the voltage across a load increase? |
The molar heat capacity of hydrogen gas and deuterium gas are nearly the same, $\pu{28.8 J K-1 mol-1}$ and $\pu{29.2 J K-1 mol-1}$, respectively, but the absolute entropy of deuterium ($\pu{145.0 J K-1 mol-1}$) is significantly larger than that of hydrogen ($\pu{130.7 J K-1 mol-1}$).
I have seen the equation that a... |
In lecture I was taught that, in a galvanic cell at standard conditions, platinum is often used as an inert electrode when the species being oxidized or reduced exists only in solution, because platinum is "inert," which means it is very stable at and resists reduction or oxidation. This concept confuses me, because "R... |
Are we technically reducing electrodes/wires for the instant that an electron passes through them? |
In a closed system (think of a typical AC system) why does refrigerant tend to condense and settle in oil?
I’ve heard that the vapor pressure of the oil is very low so that causes a pressure difference which draws the refrigerant into the oil and causes it to condense. The refrigerant is more dense than oil so it w... |
Why does refrigerant condense in oil? |
I was thinking about an allene, fucoxanthin:
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/0Cya2.png
Potentially, we can draw a resonance structure in which up to eight of the carbon-carbon double bonds have moved one position to the left, a carbocation is present somewhere along the c... |
Can allenes be used as motors or generators? |
In lecture I was taught that, in a galvanic cell at standard conditions, platinum is often used as an inert electrode when the species being oxidized or reduced exists only in solution, because platinum is "inert," which means it is very stable at its oxidation state and resists reduction or oxidation. This concept con... |
In my chemistry lab, we are testing the amphoteric properties of this metal. I understand zink can react with an acid or a base to form different compounds in solution based on pH. In one part of the experiment we are testing when ammonia in added gradually to Zn(OH)2(s) if it redissolves as Zn(OH4)^2- or if it redisso... |
In my chemistry lab, we are testing the amphoteric properties of this metal. I understand zink can react with an acid or a base to form different compounds in solution based on pH. In one part of the experiment we are testing when ammonia in added gradually to $\ce{Zn(OH)2(s)}$ if it redissolves as $\ce{Zn(OH4)^2-}$ or... |
Background - In a laboratory setting, I use typical elemental analysis (EA) to generate about 50 µg of sulfur in the form of sulfur dioxide (SO<sub>2</sub>). The EA uses a helium carrier. As an example, a sample of silver sulfide wrapped in tin falls into the reactor set to 1000 °C at the same time as an oxyg... |
Why does Sulfur dioxide incompletely freeze when entrained in a helium stream inside tubing dipped in liquid nitrogen? |
Background - In a laboratory setting, I use typical elemental analysis (EA) to generate about 50 µg of sulfur in the form of sulfur dioxide (SO<sub>2</sub>). The EA uses a helium carrier. As an example, a sample of silver sulfide wrapped in tin falls into the reactor set to 1000 °C at the same time as an oxyg... |
The things you wish you would have done before doing a PhD in Organic Chemistry? |
I've been reading that a saponification reaction typically involves NaOH or KOH. I was wondering - could anything that contains an OH group cause a saponification reaction? For instance, coconut oil + ethanol? If not, why is a "strong base" needed? |
Saponification - Oil and Alcohol? |
if current is kept zero then how do electrons move from one electrode to other electrode? How the reduction would happen if electrons doesn't move from one electrode to other electrode? |
What the current is kept zero in potentiometric cell? if current is kept zero then how do electrons move from one electrode to other electrode? |
I was checking the pH of 1 M chromic acid solution and I got around -1.7, 0.4 M had around -0.6 pH. Could these values be correct? The pH meter was calibrated before use.
I'm thinking not. I guess pH meters work in the interval 2-12 pH. |
Can you meassure a negative pH value with a pH meter? |
If molecular hydrogen is dissociated, or two hydrogen atoms in space collide, how much energy (in eV, or perhaps kJ/mol) does it take for an $H_2$ molecule to form?
|
What is the activation energy of molecular hydrogen from atomic hydrogen? |
While going through my book, I came across a problem which gave some options about the order of energy of **3s, 3p and 3d** orbitals of hydrogen atom. The correct answer was given as:
> **3s, 3p and 3d orbitals all have the same energy**
---
I also read somewhere that the order of energy of different or... |
When is the n+l rule followed when working with energy of different orbitals? |
When studying the ignition delay of a fuel, some fuel presents a negative temperature coefficient area (NTC) where an increase of initial temperature of the mixture air/fuel produces an increase of the ignition delay (see picture)
[![NTC][1]][1]
[1]: https://i.stack.imgur.com/wmMrA.png
**What is the explan... |
What is the explanation of negative temperature coefficient in ignition delay of a fuel? |
Yes, it is possible to fully decompose cinnabar to elemental mercury and sulfur.
> What conditions need to be satisfied in the new method?
Before reaching to decomposition temperature, cinnabar phase transitions to a different polymorph. Data from this paper<sup>1</sup> indicate that α-HgS (trigonal) → β-HgS (cu... |
I know that the disordered CuAu structure is based around FCC whereas the ordered CuAu structure is tetragonal. Why would the FCC structure be more stable at high temperatures? |
Why is the disordered CuAu structure more stable at high temperatures? |
I know that the disordered CuAu structure is based around FCC whereas the ordered CuAu structure is tetragonal. Why would the FCC structure be more stable at high temperatures?
For context, I was asked to explain this with the aid of a graph. I don't really know where to start |
If molecular hydrogen is dissociated, or two hydrogen atoms in space collide, how much energy (in $\pu{eV}$, or perhaps $\ce{kJ/mol}$) does it take for an $\ce{H_2}$ molecule to form?
|
What is the activation energy of creating molecular hydrogen from atomic hydrogen? |
As porphyrin pointed out, two hydrogen atoms coming together from infinite distance will tend to bond, if the energy of the bond can be dissipated. This is unlike the situation where two magnets click together and stay together (because that interaction hits an absolute minimum, rather than a roller-coaster upswing as ... |
If molecular hydrogen is dissociated, or two hydrogen atoms in space collide, how much energy (in $\pu{eV}$, or perhaps $\pu{kJ/mol}$) does it take for an $\ce{H_2}$ molecule to form?
|
No current needs to flow from an open circuit half cell. Well, no *external* current needs to flow. An equilibrium is established between the solution and the electrode. This equilibrium involves many transitions, back and forth, but is in *equilibrium*. There is a net current of *zero*.
Now, how do you measure a vo... |
If the current is kept to zero then how do electrons move from one electrode to the other electrode? How would the reduction happen if electrons don't move from one electrode to the other electrode? |
If the current is kept to zero in a potentiometric cell then how do electrons move from one electrode to the other? |
Considering 100mL 0.1M H3A and 0.1M NaOH Titration Curve.[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/gVdbX.jpg
I have understood the half equivalence points but couldn't understand the reason why pH = [pKa1 + pKa2]/2 at equivalence points.
So I tried to derive this and for that I ... |
What is a better laboratory set up for dehydration of ethanol to form ethene? |
I was checking the $\mathrm{pH}$ of $\pu{1 M}$ chromic acid solution, and I got its $\mathrm{pH}$ around -1.7. Yet, $\mathrm{pH}$ of $\pu{0.4 M}$ solution was around -0.6. Could these values be correct? The $\mathrm{pH}$ meter was calibrated before use.
I'm thinking not. I guess $\mathrm{pH}$ meters work in the inte... |
S. Cotton's *Lanthanide and Actinide Chemistry* reports that naphthalene can be oxidized to naphthalene-1,4-dione using cerric ammonium sulfate (CAS), MeCN, H<sub>2</sub>SO<sub>4</sub>, and H<sub>2</sub>O. No mechanism was provided, and I was unable to find a complete mechanism for this transformation in the literature... |
Relative humidity is defined (((pressure of h2o vapours/vapour pressure of h2o at that temperature) times 100))if temperature is fixed And if I apply le chateliers principle then relative humidity should always try to be 100%? |
Why doesn't relative humidity tend to 100%? |
S. Cotton's *Lanthanide and Actinide Chemistry* reports that naphthalene can be oxidized to naphthalene-1,4-dione using cerric ammonium sulfate (CAS), $\ce{MeCN, H2SO4},$ and $\ce{H2O}$. No mechanism was provided, and I was unable to find a complete mechanism for this transformation in the literature. From what I did f... |
When in a closed container a small amount of liquid is introduced then at a fixed temperature $T$ we will have a vapor-liquid equilibrium and the pressure of the vapor at that temperature is called vapor pressure. In order to derive the relation between vapor pressure and temperature we must equate their chemical poten... |
Is vapor-liquid equilibrium in contradiction with Pascal's law? |
S. Cotton's *Lanthanide and Actinide Chemistry* reports that naphthalene can be oxidized to naphthalene-1,4-dione using cerric ammonium sulfate (CAS), $\ce{MeCN, H2SO4},$ and $\ce{H2O}$.<sup>1</sup> No mechanism was provided, and I was unable to find a complete mechanism for this transformation in the literature. From ... |
The [iodine clock reaction](https://en.wikipedia.org/wiki/Iodine_clock_reaction) is a fun experiment shown to undergraduates to illustrate that chemical reactions can show periodic behaviour. Presumably, or hopefully, there is a [system of differential equations](https://en.wikipedia.org/wiki/System_of_differential_equ... |
What do the phase space and slope fields of the iodine clock reaction look like? |
I've been experimenting using electroplating, and I recently made a solution by placing 2 copper pieces connected to a voltage source, in water. I suspect that this created Copper (II) Hydroxide, as it matches the color of that specific solution (green-blue) and doesn't stay dissolved in the water (it sinks to the bott... |
I'm in general chemistry, and I was wondering how ionic species crystallize and form the shapes they do, specifically in regard to the Struvite precipitate $\ce{MgNH_4PO_4. 6H_2O}$.
Deconstructing the ionic species, we get $\ce{NH_4^+}$, which does not have a dipole moment (I think), $\ce{PO_4^{3-}}$, which also do... |
**TL;DR**: Guignet's green is a green pigment with composition $\ce{Cr2O3.2H2O}$.
**Long answer**
Chromium oxide is largely used as a green pigment in various industrial and commercial purpose as it is the only green pigment which can withstand both acidic as well as alkaline environment. It is also used as perma... |
Are there any tests which distinguish between triglycerides and polar lipids/impurities that can be conducted in a high school setting? |
I've been experimenting using electroplating, and I recently made a solution by placing two copper pieces connected to a voltage source, in water. I suspect that this created copper(II) hydroxide, as it matches the color of that specific solution (green-blue) and doesn't stay dissolved in the water (it sinks to the bot... |
If atmospheric air masses had had constant temperature, the relative humidity would have converged to 100%.
But, because of dynamic nature of atmosphere behavior, there are processes of cooling down and warming up of air. The former eventually leads to water condensation and precipitation, while the latter leads to ... |
If atmospheric air masses had had constant temperature, the relative humidity would have converged to 100%.
But, because of dynamic nature of atmosphere behavior, there are processes of cooling down and warming up of air. The former eventually leads to water condensation and precipitation, while the latter leads to ... |
When studying the ignition delay of a fuel, some fuel have a negative temperature coefficient area (NTC) where an increase of initial temperature of the mixture air/fuel produces an increase of the ignition delay (see picture)
[![NTC][1]][1]
[1]: https://i.stack.imgur.com/wmMrA.png
**What is the explanatio... |
The typical progression (in books, YouTube videos) of explanation of chiral carbons in a compound is as follows:
1. Chiral compounds are non-superimposable by their mirror-image;
2. It is easily seen that only carbon atoms with all substituents different are chiral;
3. In a carbon compound with more than one at... |
What exactly is a 'chiral centre' in a carbon compound? |
Relative humidity is defined as:
$\frac{pressure of H_{2}O vapours}{vapour pressure of h2o at that temperature}$ x $100$
Suppose the temperature is fixed and I apply Le Chatalier's principle, then would relative humidity always try to be 100%? |
Relative humidity is defined as:
$$\frac{\text{pressure of $\ce{H2O}$ vapours}}{\text{vapour pressure of $\ce{H2O}$ at that temperature}} \times 100$$
Suppose the temperature is fixed and I apply Le Chatalier's principle, then would relative humidity always try to be 100%? |
When studying the ignition delay of a fuel, some fuel have a negative temperature coefficient area (NTC) where an increase of initial temperature of the mixture air/fuel produces an increase of the ignition delay:
[![NTC][1]][1]
What is the explanation of the NTC phenomena? Why does the ignition delay increases w... |
Electronegativity is the tendency of atoms in covalent bonds to attract electrons closer to themselves (ill admit I realised ions do not form covalent bonds only after I finished writing).
Electronegativity depends on a variety of factors including the number of protons, the number of electrons in the outer shell a... |
Which is more electronegative, Anions or Cations? |
This question is about light emission, which may overlap with physics, but I am most interested in combustion and types of flame (incandescence, petrochemical fuel flames, nuclear ractions).
Consider [this article about candle flames][1]. In it they describe how a candle flame only emits light where it has contact w... |
Does all fire only emit llight on its outermost shell? |
Does all fire only emit light on its outermost shell? |
TLDR: They deal with similar, but different, notions of "chirality".
---
First, the definitions, from the [IUPAC Gold Book](https://goldbook.iupac.org):
> **asymmetric carbon atom**
> The traditional name (van't Hoff) for a carbon atom that is attached to four different entities (atoms or groups), e.g. Cabc... |
**The answer is NO.**
The article you quote makes a completely unwarranted generalisation that "all flames are hollow". This is true of some flames but only because the fuel that is burning is only able to burn when mixed with oxygen from the air. In those flames, the flame is "hollow" because only in regions where ... |
"Sugar rockets" or sparklers made of metal fillings, potassium nitrate and some carbon compound are easily made, and there is a lot of tutorials and videos on the internet suggesting them as relatively safe and non toxic DIY fireworks.
However reading on the potassium nitrate reaction, it decomposes to potassium nit... |
Should I be worried about the waste from "sugar rockets" and other potassium nitrate fireworks? |
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