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Is it $\ce{[Pt(NH3)Cl2(NO2)]}$ or $\ce{[PtCl2(NH3)(NO2)]}$? |
I think your problem with this reaction lies in the easily confused term *syn* and *cis*. Both appear to mean that two functional groups are oriented in the same direction. On a cyclic molecule, *syn* and *cis* are the same. However, *cis* is a stereochemical descriptor and *syn* is a conformational descriptor. Simplif... |
Presumably, it would be expensive to use ozone ($\ce{O3}$) as an oxidizer instead of $\ce{O2}$, but would the extra oomph be worth it? Or does $\ce{O2}$ provide as much thrust/energy/heat as can be provided, given the liquid hydrogen propellant?
---
<sub>I figured Chemistry was better than Physics, Engineering or... |
Why don't NASA or SpaceX use ozone as an oxidizer for rocket fuels? |
Cycloaddition reactions of the form [4+2] and [2+2] are always suprafacial, as the geometry is too constrained to allow for antarafacial interaction between the FMO's. However, **for cycloaddition of longer chains, say [6+6] cycloaddition, can the cycloaddition be antarafacial?**
Here's a small scheme I came up with... |
I always had the misconception that when people say ions conduct electricity, what they actually mean is a connection is made between the cathode and the anode by the ions and electrons can flow from the cathode to the anode through this connection.
However, I recently learned that ions conduct electricity because c... |
Do ions still "conduct electricity" if a physical connection made by aqueous electrolytes between the anode and the cathode is nonexistent? |
I have learnt that, for a **weak acid strong base** titration, pKa = pH at the half equivalence point.
However, the same conclusion is not drawn when discussing **strong acid** strong base titrations.
Why does the above only hold for weak acid strong base and not strong acid strong base?
Similarly, why is pO... |
pKa = pH for strong acid- strong base? |
Why does Ethylene Glycol have higher boiling point than Propylene Glycol? |
This is a semiconductor related question, but in order to understand the acceptor level energy state of Boron in Silicon, I figured I'd ask here for hints.
Boron is P type material when introduced in a semiconductor like Silicon. It forms 3 covalent bonds with silicon, leaving one silicon atom frustated, not forming a... |
I want to further expound upon your newly developed misconception as written in your comments although Maurice has already explained it well.
> I see what I'm overlooking here. So what happens is that the solution
> can become charged to create an electric field that cancels out the
> electrodes' ability to attrac... |
I'm just getting started with quantum chemistry using some simple test problems. I have a few of the software packages installed (ASE, Psi4, GPAW etc) and everything is working - no issues with the software itself - but there is a bewildering variety of methods, from semi-empirical (PM7) to DFT (B3LYP) to coupled clus... |
Which quantum chemistry approximation to use? |
This is a semiconductor related question, but in order to understand the acceptor level energy state of Boron in Silicon, I figured I'd ask here for hints.
Boron is P type material when introduced in a semiconductor like Silicon. It forms 3 covalent bonds with silicon, leaving one silicon atom frustated, not forming a... |
This is a semiconductor-related question, but in order to understand the acceptor level energy state of boron in bilicon, I figured I'd ask here for hints.
Boron is a p-type material when introduced in a semiconductor like silicon. Boron forms three covalent bonds with silicon, leaving one silicon atom frustrated, n... |
The the authors of the paper cited below have conducted a study on the anticholinesterase activity of various carbamates derived from phenothiazine. The authors measured the inhibition rate constants of rivastigmine for acetylcholinesterase and butyrylcholinesterase as (1.13* 10^3)/M* min and (129 * 10^3)/M* min respec... |
The the authors of the paper cited below have conducted a study on the anticholinesterase activity of various carbamates derived from phenothiazine. The authors measured the inhibition rate constants of rivastigmine for acetylcholinesterase and butyrylcholinesterase as (1.13* 10^3)/M* min and (129 * 10^3)/M* min respec... |
Darvesh et al. \[[1](https://doi.org/10.1021/jm8002075)\] have conducted a study on the anticholinesterase activity of various carbamates derived from phenothiazine. The authors measured the inhibition rate constants of rivastigmine for acetylcholinesterase and butyrylcholinesterase as $\pu{1.13E3 M^-1 min^-1}$ and $\p... |
I have learnt that for a *weak acid — strong base* titration, $\mathrm{p}K_\mathrm{a} = \mathrm{pH}$ at the half equivalence point.
However, the same conclusion is not drawn when discussing *strong acid — strong base* titrations. Why does the above only hold for weak acid — strong base and not strong acid — strong ... |
pKa = pH for strong acid — strong base? |
> Arrange the following pyridine derivatives in the order of increasing stability
of adduct formed with $\ce{BBr3}.$ Explain briefly.
>
> [![I: 3‐methylpyridine; II: 2‐methylpyridine; III: 3,5‐dimethylpyridine][1]][1]
I'm pretty confused about which structure is the most stable. I'd say structure **III** is the m... |
It means is that no electron can have same n , l and $m_l$ but can have two different spin quantum number.
I want to know why is this rule valid?Means there must be some other things happening also Inside that atom which forces this rule to be true.
I got to know from web that electron dual behaviours and electromagn... |
Why is Pauli’s exclusion principle true? |
What does Pauli’s exclusion principle mean in atomic or fundamental way? |
A1: There is no displacement of the wall, forces are in equilibrium with zero net force. There are initiated stronger vibrations on warmer wall side by energetic hot air molecules. And weaker vibrations on colder wall side by energy leaching cold water molecules .
A2a: If the wall initial temperature was the cold wa... |
Is the correct formula for diamminechloridonitrito-n-platinum(II) $\ce{[Pt(NH3)Cl2(NO2)]}$ or $\ce{[PtCl2(NH3)(NO2)]}$?
According to IUPAC, the sequence of symbols within the coordination entity should be written in the following order:
1. The symbol of the **central metal atom** is written first.
2. The ***li... |
What is the correct formula for diamminechloridonitrito-n-platinum(II)? |
My sir told me that Energy required to remove an electron from one orbit to another depends on hf * n. Where n means the no of photons that will be emitted and hf is end energy of one photon.
My question is that if I continuously hit many photons.Why doesn’t the electron come out then since the energy also increases ... |
My sir told me that Energy required to remove an electron from one orbit to another depends on hf * n. Where n means the no of photons that will strike on a metal surface and hf is energy of one photon.(Means energy of each photon is going to be 2eV)[Like the example below I have written ].
My question is that if I co... |
The photoelectric effect is explained in such a way that some people get it right away, but others (including physicists before Einstein) don't/didn't.
Try this: take a photon gun that shoots one photon at a time, with a selectable energy. Fire it at the metal target. Here's what will happen: At low energies (reddis... |
I recently started making [oral rehydration therapy][1] for someone I'm taking care of who developed POTS after COVID-19 infection. (ORT was recommended by their doctor.) I use the standard ingredients of ORT: sodium chloride, sodium citrate, potassium chloride and dextrose/glucose. To add some flavor, I tried blending... |
Why does sodium citrate in water turn black when blueberries are added? |
I make my own sodium ascorbate with ascorbic acid and sodium bicarb. It's easy, I get the vitamin c off ebay and the baking soda from the store.
Is there a similar way to make magnesium ascorbate: ingredients easily available, room temp, etc? |
Is there an "off the shelf" way to make magnesium ascorbate? |
Using your diagram, the boron-silicon bond with only the silicon electron has only half of the possible electron content. A "hole" as you said. The hole is not confined to the one $B-Si$ bond, but can be in any of the 4 positions. It's not like the boron sits there and the silicon pops its electron into the potential ... |
Using your diagram, the boron-silicon bond with only the silicon electron has only half of the possible electron content. A "hole" as you said. The hole is not confined to the one $\ce{B-Si}$ bond, but can be in any of the 4 positions. It's not like the boron sits there and the silicon pops its electron into the poten... |
If enthalpy is a state function, shouldn't the change in enthalpy be the same between a given initial and final state, regardless of how the change took place? Kirchoff's equation describes this variation as ∆H<sub>T<sub>2</sub></sub> = ∆H<sub>T<sub>1</sub></sub> + ∆C<sub>p</sub> (T<sub>2</sub> - T<sub>1</sub>) . </n> ... |
Why does enthalpy change differ in a chemical reaction because of temperature? |
If enthalpy is a state function, shouldn't the change in enthalpy be the same between a given initial and final state, regardless of how the change took place? Kirchoff's equation describes this variation as
$$\Delta H_{T_2} = \Delta H_{T_1} + \Delta C_p (T_2 - T_1).$$
I'm guessing that this change in enthalpy chang... |
I assume a [milk of magnesia][1], what is essentially suspension of [Mg(OH)2][2] is commercially available for per oral usage as antacid or laxative.
Mixing with ascorbic acid solution will produce water and magnesium ascorbate.
[1]: https://www.google.com/search?q=%22milk%20of%20magnesia%22
[2]: http://M... |
The book *Cholinesterases and Anticholinesterase Agents* gives examples of bis-quaternary aromatic compounds that are capable of inhibiting acetylcholinesterase. Page 400 gives examples of some such compounds, designated 2842CT, 3443CT, 3116CT, 3152CT, and 3113CT. The first three are neither organophosphates nor carbam... |
Can bis-quaternary aromatic compounds act directly on acetylcholine receptors? |
On the left image.. we see that specific conductivity is increasing at a decreasing rate, eventually plateauing as it reaches a maximum. I am unable to reconcile this with the molar conductivity graph to the right... shouldn't the decreasing molar conductivity be decreasing at an increasing rate... why does it plateau ... |
Why does the molar conductivity plot behave this way? |
I am filling up this table but I'm not sure about what it means in the mass row, amount of substance, molecule quantity.
In mass do I just have to repeat 16 in the second column or do I need to put the mass of a single molecule?
Amount of substance 1 mole of the molecule or 5 moles of each atom?
I'm confused.
... |
Could you use the Wittig reagent to attack a metal-oxo bond and replace the oxygen with a carbene?
Specifically is it possible for the Wittig reagent to do sigma-bond metathesis with an electrophilic metal attached to an oxygen?
As I'm trying to understand the mechanism, I would really appreciate an explanation f... |
Based on some of the methods of studying starches in rice I looked at, I found that there are two general distinctions:
- ones that focus on the ratio between amylose and amylopectin
- ones that focus just on amylose, measuring percentage content
The former included methods such as electrophoresis, amperometric, p... |
How does iodine react with amylose and amylopectin, and can iodine colorimetry be used to determine the ratio between the two starches? |
There is a statement in my book that
By rotating a small set of peddles , let us say we do mechanical work of 1kJ.Let the new state then be B and A as initial state.
It is found that $T _B$>$T_A$.Let internal energy of system be $U_B$.
They say that $\delta$U = $U_B$ -$U_A$.
My question are that do we assume $T_A$... |
Best Cheminformatics API for drawing SMARTS reactions? |
In chemical bonding, I am taught a formula that compares the Solvation Energy and the Lattice Energy of an ionic compound which is being dissolved in a polar solvent (could be water, could be something else).<br/>
The formula is:<br/>
$$\left\lvert r_+ -r_-\right\rvert$$
where $r_+$ denotes radius of cation and $r_-... |
Could you use the Wittig reagent to attack a metal–oxo bond and replace the oxygen with a carbene?
Specifically, is it possible for the Wittig reagent to do σ-bond metathesis with an electrophilic metal attached to an oxygen?
As I'm trying to understand the mechanism, I would really appreciate an explanation for ... |
In chemical bonding, I am taught an expression that compares the Solvation Energy and the Lattice Energy of an ionic compound which is being dissolved in a polar solvent (could be water, could be something else).<br/>
The expression is:<br/>
$$\left\lvert r_+ -r_-\right\rvert$$
where $r_+$ denotes radius of cation a... |
**OpenEye** is probably the most powerful and fast [depiction SDK][1], but it costs money. Also OpenEye is a low-level, cumbersome, complicated library - so I'd consider it only if you have very sophisticated needs. It's written in C++, but it has Python/Java wrappers.
**CDK** (Java) has an OS-agnostic [depiction AP... |
There is a statement in my book:
> THERMODYNAMICS
>
> ***One way***: We do some mechanical work, say $\pu{1 kJ},$ by rotating a set of small paddles and thereby churning water. Let the new state be called $\mathrm{В}$ state and its temperature, as $T_\mathrm{B}.$ It is found that $T_\mathrm{B} > T_\mathrm{A}$ and ... |
Using two approximations for the dissociation of a weak acid, we can write
**$K_\mathrm{a}$= $\frac{[H^+(aq)]^2}{[HA(aq)]}$**
One of these two approximations we use is that the concentration of the acid HA has not changed upon dissociation, because the dissociation of a weak acid is so small compared to the start... |
Why are some weak acid equilibrium approximations invalid in very dilute solutions? |
Using two approximations for the dissociation of a weak acid, we can write
$$K_\mathrm{a}= \frac{[\ce{H+(aq)}]^2}{[\ce{HA(aq)}]}$$
One of these two approximations we use is that the concentration of the acid HA has not changed upon dissociation, because the dissociation of a weak acid is so small compared to the ... |
In soda lime decarboxylation, why do we use CaO(lime)?
It seems as if it is dehydrating agent, but why don't we use $P_4O_{10}$ even or absolutely no dehydrating agent because the heat would be enough to dehydrate the container as the temperature is very high? |
Why does hydrogen bonding require a lone pair of electrons on the partially negative atom? They would still be partially negative even without the lone pair right? Or does a bond exist, but is much more negligible compared to when a lone pair is there? |
Why does hydrogen bonding require a lone pair? |
In soda lime decarboxylation, why do we use CaO(lime)?
[![enter image description here][1]][1]
It seems as if it is dehydrating agent **(to keep NaOH dry)**,
**Main question**
but why is dehyderating agent required if the heat would be enough to dehydrate the container as the temperature is very high(expec... |
In soda lime decarboxylation, why do we use CaO(lime)?
$$\ce{CH3COOH + NaOH ->[\Delta][CaO]CH4 + Na2CO3}$$
It seems as if it is dehydrating agent **(to keep NaOH dry)**,
**Main question**
but why is dehyderating agent required if the heat would be enough to dehydrate the container as the temperature is very ... |
Why do we use calcium oxide $\ce{CaO}$ in soda lime decarboxylation?
$$\ce{\underset{sodium acetate}{CH3COONa} + \underset{sodium hydroxide}{NaOH} ->[\Delta][CaO] \underset{methane}{CH4} + \underset{sodium carbonate}{Na2CO3}}$$
It seems as if it is dehydrating agent to keep NaOH dry), but why is the dehydrating a... |
when does a system of mass-action reactions satisfy detailed balance for *any non-zero choice of the rate constants*?
consider a trivial example:
$X + Y \ce{<-->[k1][k2]} XY$
satisfies detailed balance for any $k_1, k_2 > 0$. Here is a less trivial example:
$A + X \ce{<-->[k1][k2]} AX$
$B + X \ce{<-->[k... |
when is a system of mass-action reactions guaranteed to satisfy detailed balance? |
Presumably, it would be expensive to use ozone ($\ce{O3}$) as an oxidizer instead of $\ce{O2}$, but would the extra oomph be worth it? Does $\ce{O2}$ provide as much thrust/energy/heat as can be provided, given the liquid hydrogen propellant?
---
<sub>I figured Chemistry was better than Physics, Engineering or As... |
Why doesn't NASA or SpaceX use ozone as an oxidizer for rocket fuels? |
### Extraction and GC-MS or maybe LC-MS, if you really need to measure these specific impurities
I don't know a lot about this area, but you are looking for very low amounts of impurities. For ethylene oxide, for example, your desired detection limit of 0.07 mg in a 10 g sample corresponds to 7 parts per million, o... |
Let's take your questions one at a time.
### Are there any alternative ways to purify primary amines from a complex mixture that I am unaware of?
Your end application is LC-MS. There are plenty of papers on amine-specific derivatization methods for metabolome analysis. [Here](https://pubs.acs.org/doi/abs/10.102... |
I want to purify all primary amine containing compounds in a complex mixture (cell-extracted metabolites). I am not aware of any published methods to do so, so I am thinking to make my own using reversible Schiff base immobilization.
My input is a 1 mL metabolite extract and contains hundreds of compounds with a tot... |
Let's take your questions one at a time.
> 1. Are there any alternative ways to purify primary amines from a complex mixture that I am unaware of?
Your end application is LC-MS. There are plenty of papers on amine-specific derivatization methods for metabolome analysis. For example, there is one by Zhao et al. \... |
I am using PLA for 3D printing, and I know it does not degrade well in the wild. I would like to know if there is a chemical process I could use to treat it at home.
Specifically, I am looking for a cleaner alternative than throwing my 3d printing scraps in the garbage, so I wouldn't be generating toxic components ... |
I'm probably overthinking this but would appreciate a peer check.
Mole fraction of element $i$ in compound: $\frac{\mathcal{M}_i}{\mathcal{M}}$
I used script M so as not to confuse with molar mass (often denoted as capital M).
Atom fraction of element $i$ in compound: $\frac{N_i}{N}$
Now, if Avogadro's numb... |
Are the protons in methylene groups of achiral molecules such as propane-1,2,3-triol or 3-hydroxypentanedioic acid diastereotopic?
Consider propane-1,2,3-triol. To me, replacing one of the protons in either -CH<sub>2</sub> with an arbitrary X nuclei creates (what I work out as) 2 diastereomers. However, NMR simulati... |
The fallacy lies in the assumption that mole fraction The denominator cannot have the same number of atoms as in the numerator.
For example, take $\ce{Na2SO4}$
what is the atom fraction of Na: 2/(2+1+4) = 2/7
What about the mole fraction of Na? It 2$N_A$/$N_A$(2+1+4)= 2/7
However, this "simple" formula of ... |
I've run into an issue collecting measurements on deionized water in the 1050-1200n m range. To determine the sensitivity of my spectrophotometer in this range, I've acquired measurements on pure deionized water in double-beam mode using two identical quartz cuvettes. I have taken measurements at several time steps nea... |
The fallacy lies in the assumption that mole fraction and the number fraction are always the same.
For example, take $\ce{Na2SO4}$
what is the atom fraction of Na: 2/(2+1+4) = 2/7
What about the mole fraction of Na? It 2$N_A$/$N_A$(2+1+4)= 2/7
However, this "simple" formula of yours breaks down in the case ... |
If the two bromines are attached at opposite ends of the molecule, why are they both labelled with a 6?
Also, why is 6,6′-dibromoindigo not called 1,1′-dibromoindigo if carbons in a ring are numbered according to their substituents, and bromine is the substituent, therefore the carbon it is attached to should be c... |
Why is Tyrian purple called 6,6′-dibromoindigo? |
The structure of one particular isomer of 4-chlorohepta-2,5-diene is shown here. I am confused about how two of the propenyl groups attached to the central carbon have the same atoms with different configurations.
<img src="https://i.stack.imgur.com/aIKPF.png" height="150" alt="Structure of (Z,E)-4-chlorohepta-2,5-d... |
What is the oxidation state of nitrogen in ammonium nitrate? |
I have this problem:
> From a stock solution of initial concentration of $10~\mathrm{mg/l}$, I take $2\,\mathrm{ml}$, and then I add $10\,\mathrm{ml}$ of distilled water.
I am supposed to calculate the final concentration. I have solved the problem in this way.
$$\begin{align}
C_1 \cdot V_1 &= C_2 \cdot V_2 \... |
Wikipedia article on ortho effect suggests that o-toluic acid is more acidic than benzoic acid. This fact is rationalized by suggesting that steric effect causes COOH group to "twist" out of the plane and which increases it's acidity as it inhibits "cross-conjugation"that it was previously taking part in.
My instru... |
From my understanding, the basic notions of acidity can be explained by considering a cup of pure water, and then adding a substance to it which creates either free $H^+$, or free $H_3O^+$ and $H_5O_2^+$ etc...
And these ions are free to react and give rise to what we consider acidic behavior. The classic example i... |
Is there a notion of generalized acidity for lithium ions? |
Why am I getting higher conversion values of isopropanol dehydration over a zeolite catalyst than n-propanol dehydration? |
From my understanding, the basic notions of acidity can be explained by considering a cup of pure water, and then adding a substance to it which creates either free $\ce{H+}$, or free $\ce{H3O+}$ and $\ce{H5O2+}$ etc...
And these ions are free to react and give rise to what we consider acidic behavior. The classic ... |
Is there a physical meaning to the SCF energy of a molecule obtained using pseudopotentials to represent the core electrons of heavy atoms (for example gold)?
I've been running calculations in Gaussian on a system with a number of gold atoms and I became curious whether my use of pseudopotentials for the gold core ... |
# What's up with all that magic? (A chapter formerly known as Introduction)
The hunt for for the holy grail of density functional theory (DFT) has come a long way.<sup>\[1\]</sup> Becke states in the introduction of the cited paper:
> Density-functional theory (DFT) is a subtle, seductive, provocative business. Its... |
I noticed when looking through the [Basis set exchange](https://www.basissetexchange.org/) website that the 6-311 Pople basis sets don't at all match their formulation once you go past the 2nd row of the periodic table. For example, oxygen's basis set looks like this (in Gaussian input format):
O 0
S ... |
Is the correct formula for diamminechloridonitrito-n-platinum(II) $\ce{[Pt(NH3)2Cl(NO2)]}$ or $\ce{[PtCl(NH3)2(NO2)]}$?
According to IUPAC, the sequence of symbols within the coordination entity should be written in the following order:
1. The symbol of the **central metal atom** is written first.
2. The ***li... |
>Would total evaporation of isopropanol (isopropyl alcohol) at room temperature leave residue? And, why it is able to evaporate although it does not reach its boiling point? |
Alkalinity is a measure of the water's ability to neutralize acidity and is expressed in levels of bicarbonates, carbonates, and hydroxides.
How can water that is slightly acidic, e.g. 5.5-6.5, still boast any alkalinity? Or put another way, is there a maximum level of alkalinity for water at any given acidic pH?
... |
How can water below a pH of 7 still be alkaline? |
*"Electrons are negatively charged, therefore, two electrons repel each other. When electrons are paired in a 3p orbital there is electron pair repulsion which causes the energy of the electrons to increase. Increased energy makes the electron easier to remove and therefore the ionisation energy decreases."*
I found... |
As electron energy increases, does ionisation energy decrease? |
When we talk about energy bands, we are talking about mixing of orbitals on different atoms (AOs) with similar energies. First, assume simple models. In the solid, the structure is very regular and all atoms have AOs with identical matching energies. This makes the number of orbitals available for mixing in solids very... |
H2SO4 when added to water.
$H_2so_4 + 2 H_20$ gives $SO_4^{2- }+ 2H_3O^+$
My sir explained me these reaction as H will give 2 $H^+$ ions to the base $H_2O$.So why does it not become $H_4O^+$
To try to make myself understand this , I checked my textbook.
$H_2SO4 + H_20⇌ H_30^+ + HSO_4^− $
$HSO_4^− + H_2O ⇌ H_30^+ ... |
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