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This question is mostly about the human body, but it's also about life in general.
It's not difficult to notice a big different between the abundance of elements on Earth & that in the body. I've been pondering why. Such a huge question, but here I choose to focus on the big 4. Below is my current understanding, ple... |
I'm taking my first chemistry class with a laboratory component this quarter. My first laboratory session was earlier this evening (observing simple metathesis reactions). While I found the lab work to be fairly straightforward, the fact that my safety goggles kept fogging up proved to be a moderate hinderance.
I'm ... |
Lab goggle recommendations? |
I'm taking my first chemistry class with a laboratory component this quarter. My first laboratory session was earlier this evening (observing simple metathesis reactions). While I found the lab work to be fairly straightforward, the fact that the interior surface of my safety goggles accumulated a considerable amount o... |
The problem is as follows:
> A mixture of gases consisting of $CH_{4}$ and $C_{2}H_{4}$ is let to pass over red hot
> $CuO$. Then $0.6\,g$ of $H_{2}O$ is collected along $1.185\,g$ of
> $CO_{2}$. What will be the composition of the mixture if it is known
> that the combustion was complete?.
The alternatives gi... |
How to determine the composition of a gas mixture after a combustion? |
The problem is as follows:
> A mixture of gases consisting of $\ce{CH4}$ and $\ce{C2H4}$ is let to pass over red hot
> $\ce{CuO}$. Then $\pu{0.6g}$ of $\ce{H2O}$ is collected along $\pu{1.185g}$ of
> $\ce{CO2}$. What will be the composition of the mixture if it is known
> that the combustion was complete?.
The... |
I am finding some articles about caffeine consumption confusing, because they test in units of mM instead of mg.
https://www.ncbi.nlm.nih.gov/m/pubmed/25342885/
Wikipedia says that the molar mass of caffeine is 194 g/mol. Does that mean that 1 mol caffeine equals 194 g of caffeine? And that 1mM caffeine, in turn... |
The problem is as follows:
> A mixture of gases consisting of $\ce{CH4}$ and $\ce{C2H4}$ is let to pass over red hot
> $\ce{CuO}$. Then $\pu{0.6g}$ of $\ce{H2O}$ is collected along $\pu{1.185g}$ of
> $\ce{CO2}$. What will be the composition of the mixture if it is known
> that the combustion was complete?.
The... |
why every atom has a unique spectral lines, I know spectral lines help us to identify the properties of substance , and that, s what basis of Raman effect , but I have a question, that every substance consist of atom, and every atom consist of electron, and electron are like fizzy cloud Tha, s what shordinger equat... |
The basicity order of aniline and 2,6-tertiary butyl aniline is the latter greater than the former. Why does the ortho effect not make it the other way around? Or am I missing something?[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/jlgKf.png |
Why does the ortho effect not work here? |
Why H3PO2 does not form acid salt? I didn't understood the language. |
Why H3PO2 does not form acid salt? |
Here is the [usual citation](https://www.doh.wa.gov/youandyourfamily/healthyhome/contaminants/bleachmixingdangers) for the toxic products and symptoms created upon mixing NH3 and NaOCl (not in lab conditions, which involves employing very cold dilute aqueous solutions):
>When bleach is mixed with ammonia, toxic gase... |
Why for compounds of elements in a group with larger anions have nearly constant lattice enthalpy ?
In the reasons for the decrease of the solubility of sulphates of alkaline earth metals ,it is given that '
"the size of onions being much larger compared to cations the lattice enthalpy will remain almost constant w... |
Why for compounds of elements in a group with larger anions have nearly constant lattice enthalpy? |
which compound has the larger dipole moment, CHCl3 or CBrCl3? Explain your choice |
I am trying to build a machine that converts carbon dioxide and water into gasoline (i.e. octane). Because the energy needs are so large, is there any catalyst chemical that can cause "reverse combustion" at room temperature? |
Is there any chemical that can catalyze "reverse combustion?" |
Why do compounds of elements in a group with larger anions have nearly constant lattice enthalpy?
In the reasons for the decrease of the solubility of sulphates of alkaline earth metals, it is given that:
>"the size of anions being much larger compared to cations the lattice enthalpy will remain almost constant w... |
>Consider compounds $\ce{CHCl3}$ and $\ce{CBrCl3}$: Which compound has the larger dipole moment? Explain your choice.
Okay, so I've been trying to figure it out and I thought dipole moment had to do with electronegativity but now I'm not sure. |
Why $\ce{H3PO2}$ does not form an acid salt? I didn't understand the language. |
Given a sample of an alcoholic beverage (be it beer, wine, etc..), what are possible methods to find out the ABV (_alcohol by volume_) of it with moderate accuracy?
As fas as I know, some methods exist already but are not really suitable in my condition:
* __Distillation.__ Impractical because of the apparatus ne... |
Dipole moments *are* related to electronegativity.
Draw the structures of $\ce{CHCl3}$ and $\ce{CBrCl3}$; in both cases, carbon is the central atom connected to either H, Cl, and/or Br. Then consider the electronegativities of H, Cl, and Br as compared to C. How do they pull on electrons? Does one molecule lead to a... |
Given a sample of an alcoholic beverage (be it beer, wine, etc..), what are possible methods to find out the ABV (_alcohol by volume_) of it with moderate accuracy?
As fas as I know, some methods exist already but are not really suitable in my condition:
* __Distillation.__ Impractical because of the apparatus ne... |
For us to understand the redox nature of the above examples, we have to use the definition of redox as gain or loss of electron density, not just electrons. For instance, in the reaction between sodium hydroxide and hydrochloric acid to give sodium chloride and water, chlorine is reduced by gaining electron density in ... |
If we assume that the lattices have the same structure, the lattice enthalpy is dominated by the charge of the ions and the distance between them. Since we are dealing here with cations from the same group, the charges are the same, so the remaining variable is the distance between them.
With moderately sized or ... |
Won't the lone pairs hybridize to $\mathrm{sp^3}$ making it an $\mathrm{sp^3}$-$\mathrm{sp^3}$ $\sigma$ bond? If it still is $\mathrm{p^\sigma}$-$\mathrm{p^\sigma}$ bond what is the spatial location of the lone pairs? |
Why is the F-F bond in fluorine a p-p sigma bond? |
This is how I tried to solve it:
$$\frac{2}{3} = \frac{0.67}{1}$$
$$\frac{32.06}{16} = \frac{2.00}{1}$$
$$\frac{0.66}{2.00} = \frac{0.33}{1}$$
I assumed by the result that if for every 1g of O there are 0.33g of S then if we have roughly 1g of S there must be 3 O atoms.
Is this result acceptable or do you kn... |
What is the empirical formula of a compound where the mass ratio of sulphur and oxygen is 2:3? |
>Your question: Given a sample of an alcoholic beverage (be it beer, wine, etc..), what are possible methods to find out the ABV (alcohol by volume) of it with moderate accuracy?
There are a few method used in winery industry as Karl mentioned a comment in elsewhere. I assume you want to find out better methods to ... |
In our chemistry practical paper (High school level), Inorganic salt analysis is one of the questions asked. We are given a petri dish with a sample of salt and are asked to find the cation and anion present in it.
I noticed quite a few of my classmates touching the salt (pinching it between their fingers and sprink... |
Is it safe to touch salts given to you for analysis? |
why every atom has a unique spectral lines, I know spectral lines help us to identify the properties of substance , and that, s what basis of Raman effect , but I have a question, that every substance consist of atom, and every atom consist of electron, and electron are like fuzzy cloud thats what Schrodinger equat... |
How can every atom have a unique spectral lines? |
why every atom has a unique spectral lines, I know spectral lines help us to identify the properties of substance , and that, s because of electron transition to discrete energy level , but I have a question, that every substance consist of atom, and every atom consist of electron, and electron are like fuzzy cloud... |
I'd like to make a savory version of ice cream. So I can't use sugar or any artificial sweeteners for the freezing point depression needed to control ice crystal sizes. What can I use? |
What's a non-toxic flavorless water-soluable chemical I could use for freezing point depression when making ice cream? |
It is known that order of reactivity of carbonyl derivatives with nucleophiles follow the order as,
Acyl halide> acid anhydride>ester> amide> amide derivatives
(Source: a guidebook to mechanism in organic chemistry by Peter sykes)
It is difficult to find out the order in books and online as well if we also includ... |
It is known that order of reactivity of carbonyl derivatives towards nucleophiles follow the order as:
>Acyl halide> acid anhydride>ester> amide> amide derivatives
(**Source**: "A Guidebook to Mechanism in Organic Chemistry" by Peter Sykes M.Sc., PhD., F.R.S.C., C.Chm. Fellow and Vice-Master, Christ’s College, C... |
It is known that order of reactivity of carbonyl derivatives towards nucleophiles follow the order as:
>Acyl halide> acid anhydride>ester> amide> amide derivatives
(**Source**: "A Guidebook to Mechanism in Organic Chemistry" by Peter Sykes M.Sc., PhD., F.R.S.C., C.Chm. Fellow and Vice-Master, Christ’s College, C... |
This is how I tried to solve it:
$$\frac{2}{3} = \frac{0.67}{1}$$
$$\frac{32.06}{16} = \frac{2.00}{1}$$
$$\frac{0.66}{2.00} = \frac{0.33}{1}$$
I assumed by the result that if for every $\pu{1g}$ of $\ce{O}$ there are $\pu{0.33g}$ of $\ce{S}$ then if we have roughly $\pu{1g}$ of $\ce{S}$ there must be $\ce{3 O... |
It is known that order of reactivity of carbonyl derivatives towards nucleophiles follow the order as:
>Acyl halide> acid anhydride>ester> amide> amide derivatives
(**Source**: "A Guidebook to Mechanism in Organic Chemistry" by Peter Sykes M.Sc., PhD., F.R.S.C., C.Chm. Fellow and Vice-Master, Christ’s College, C... |
I am trying to find the lifetime of sodium atoms at the $3p$ state using the relationship between the spectral linewidth and the uncertainty principle:
$$ \Delta E \times \Delta t = h / 4\pi $$
The information I have is the full-width-half-maximum (FWHM) linewidth of the sodium atomic absorption spectrum $\lambda = 9... |
Why does every element have unique spectral lines?
I have studied that spectral lines help us to identify the properties of an element. This is because after excitation when the excited electron(s) fall back to their original energy level(s), photons of certain frequency corresponding to the difference between the ... |
This is from an adapted version of Concise Inorganic Chemistry by J.D Lee.The part on primary valency is confusing me.It mentions that primary valency is the oxidation of the central metal (a number) ,on the other hand I have read that primary valenc... |
This is from an adapted version of Concise Inorganic Chemistry by J.D Lee.The part on primary valency is confusing me.It mentions that primary valency is the oxidation of the central metal (a number) ,on the other hand I have read that primary valenc... |
I am trying to find the lifetime of sodium atoms at the 3p state using the relationship between the spectral linewidth and the uncertainty principle:
$$ \Delta E \times \Delta t = h / 4\pi $$
The information I have is the full-width-half-maximum (FWHM) linewidth of the sodium atomic absorption spectrum $\lambda = \pu... |
How to find the lifetime of sodium atoms in the 3p using information on the spectral line width? |
Is there no mathematical relationship between redox potential and particle size saying that an $X$ potential should yield a $Y$ particle size? Right now its general that large redox potential results in smaller particles, but I want to know if, for example, for silver particles I use $\ce{AgNO3}$ with glucose reducing ... |
(This question is taken from Problem 1.1(b) of the book Chemical Thermodynamics: Principles and Applications.)
Based on my working, there is an additional $p(\frac{∂V}{∂T})_p$ term. Is my working incorrect? I can’t find my mistake.
|
In group 14, the double bond becomes increasingly weaker down the group. Our lecturer told us that many distannenes ($\ce{>Sn=Sn<}$) and almost all diplumbenes ($\ce{>Pb=Pb<}$) dissociate into stannylene ($\ce{R2Sn:}$) and plymbylenes ($\ce{R2Pb:}$) when dissolved in hydrocarbon solution.
The weak nature of $\ce{Sn=... |
Why do diplumbenes (Pb=Pb double bonded compounds) break apart in hydrocarbon solution? |
(This question is taken from Problem 1.1(b) of the book Chemical Thermodynamics: Principles and Applications.)
“Prove $(\frac{∂H}{∂T})_p = (\frac{∂U}{∂T})_V + [V - (\frac{∂H}{∂p})_T](\frac{∂p}{∂T})_V$”
First, I expressed $H$ as $U + PV$, and took the partial derivative against $T$, keeping pressure constant:
... |
Why do lighter elements have ionic charges so strongly related to the group number? For example, why does Al only show +3 ionic charge? The basic concept of stability in an ionic compound is that lattice energy is greater than the sum of ionisation energy and electron gain enthalpy. Why can't Al show +1 or +2 states? I... |
Why are stable ionic charges so strongly related to the group number? |
Why do lighter elements have ionic charges so strongly related to the group number? For example, why does $\ce{Al}$ only show +3 ionic charge? The basic concept of stability in an ionic compound is that lattice energy is greater than the sum of ionisation energy and electron gain enthalpy. Why can't $\ce{Al}$ show +1 o... |
According to Werner's theory, metal ions have two types of valency-primary and secondary, where the primary valency is said to be satisfied by negative ions only, and the secondary valency can be satisfied by positive ligand, negative or neutral molecule.
My question here is:
While formation of complex compounds, ... |
>Prove: $$(\frac{∂H}{∂T})_p = (\frac{∂U}{∂T})_V + [V - (\frac{∂H}{∂p})_T](\frac{∂p}{∂T})_V$$
(This question is taken from Problem 1.1(b) of the book "Chemical Thermodynamics: Principles and Applications")
First, I expressed $H$ as $U + PV$, and took the partial derivative against $T$, keeping pressure constant... |
(This question is taken from Problem 1.1(b) of the book Chemical Thermodynamics: Principles and Applications.)$\require{begingroup} \begingroup \newcommand{\pd}[3]{\left(\frac{\partial #1}{\partial #2}\right)_{\!#3}}$
> Prove $$\pd HTp = \pd UTV + \left[ V - \pd HpT \right] \pd pTV.$$
First, I expressed $H$ as $... |
(This question is taken from Problem 1.1(b) of the book Chemical Thermodynamics: Principles and Applications.)$\require{begingroup} \begingroup \newcommand{\pd}[3]{\left(\frac{\partial #1}{\partial #2}\right)_{\!#3}}$
> Prove $$\pd HTp = \pd UTV + \left[ V - \pd HpT \right] \pd pTV.$$
First, I expressed $H$ as $... |
Pressure turning out to be zero? Always? |
I understand what the standard molar entropy is, and how to use it in calculations, but I'm interested in understanding exactly how it's defined and measured.
My recollection from a long time ago is that it goes roughly like this:
* for each element, assume that its entropy goes to zero at 0 kelvin when it's in ... |
What is the precise definition of standard molar entropy? |
I do recall researching on what can cause storage bottles to fail with age, and my recollection included the obvious (like the chemical nature of what is being stored, heating as your shed is likely not air-conditioned and the action of direct or diffused sunlight) together with other things I would not have expected.
... |
Solid silicon dioxide has a giant lattice structure with single covalent bonds, while in the gas phase it has a molecular carbon dioxide-like structure. But what about in the liquid phase?
Would it be formed of molecules as well, or are there still only single covalent bonds that form and reform? Or is it more like ... |
Why does every element have unique spectral lines?
I have studied that spectral lines help us to identify the properties of an element. This is because after excitation when the excited electron(s) fall back to their original energy level(s), photons of certain frequency corresponding to the difference between the ... |
How can every atom have unique spectral lines? |
I do recall researching on what can cause storage bottles to fail with age, and my recollection included the obvious (like the chemical nature of what is being stored, heating as your shed is likely not air-conditioned and the action of direct or diffused sunlight) together with other things I would not have expected.
... |
I do recall researching on what can cause storage bottles to fail with age, and my recollection included the obvious (like the chemical nature of what is being stored, heating as your shed is likely not air-conditioned and the action of direct or diffused sunlight) together with other things I would not have expected.
... |
I am sorry to see that they are still teaching these concepts of the 19th century as facts. The concept of primary valence and secondary valence is a translation of Werner's terminology (Nobel) as Hauptvalenz and Nebenvalenz. Haupt means something "main" and neben means something "extra, supplementary". What is valence... |
I do recall researching on what can cause storage bottles to fail with age, and my recollection included the obvious (like the chemical nature of what is being stored, heating as your shed is likely not air-conditioned and the action of direct or diffused sunlight) together with other things I would not have expected.
... |
I do recall researching on what can cause storage bottles to fail with age, and my recollection included the obvious (like the chemical nature of what is being stored, heating as your shed is likely not air-conditioned and the action of direct or diffused sunlight) together with other things I would not have expected.
... |
I am sorry to see that they are still teaching these concepts of the 19th century as facts. The concept of primary valence and secondary valence is a translation of Werner's terminology (Nobel) as Hauptvalenz and Nebenvalenz. Haupt means something "main" and neben means something "extra, supplementary". What is valence... |
Let's say we have a conjugated system like this one:
[![4-nitro-(E)-stilbene][1]][1]
Now, the delocalisation of the benzene electrons with the nitrate system means that the ortho, and para positions on the immediate benzene ring would be more electron deficient than the meta position. This effect will be seen in ... |
How far does the delocalisation (resonance) effects for substituents extend for a conjugated system? |
Because life uses whatever it finds useful. And organic compounds with nitrogen can be easily synthesised, metabolized and may have many useful properties. And also, various stable organic compounds with nitrogen will just come into into existence in abiogenic conditions.
Why though? Well, nitrogen-carbon bonds are ... |
I need to retro-synthetically design a valid synthesis plan (in 2 steps, from cheap starting materials available over at Sigma Aldrich) for a target compound, pictured below.
[![enter image description here][1]][1]
How would I go about doing this?
[1]: https://i.stack.imgur.com/PXRi7.png
|
How to development of retrosynthesis plan for this molecule? |
I do recall researching on what can cause storage bottles to fail with age, and my recollection included the obvious (like the chemical nature of what is being stored, heating as your shed is likely not air-conditioned and the action of direct or diffused sunlight) together with other things I would not have expected.
... |
I was studying for my freshman chemistry course, and ran into a mind-boggling contradiction.
We know, at equilibrium, entropy is at a maximum:
$$\left(\frac{\partial S}{\partial V}\right)_U=0$$
From the first law
$$dU=TdS-pdV$$
which leads to
$$\left(\frac{\partial U}{\partial S}\right)_V=T$$
From th... |
Pressure turning out to be zero? |
I was studying for my freshman chemistry course, and ran into a mind-boggling contradiction.
We know, at equilibrium, entropy is at a maximum:
$$\left(\frac{\partial S}{\partial V}\right)_U=0$$
From the first law
$$dU=TdS-pdV$$
which leads to
$$\left(\frac{\partial U}{\partial S}\right)_V=T$$
From th... |
What is the symmetry of dxy orbital? |
I don't have specific product recommendations (and I think they're discouraged in general on SE), but these are the general principles:
You'll only get condensation on goggles (or anything else) if they're cooler than the dewpoint of the air contacting them. **If your goggles are cold, you'll get condensation.**
... |
I understand what the standard molar entropy is, and how to use it in calculations, but I'm interested in understanding exactly how it's defined and measured.
My recollection from a long time ago is that it goes roughly like this:
* for each element, assume that its entropy goes to zero at 0 kelvin when it's in ... |
> Is the effective nuclear charge just a semiempirical value fitted to approximate the total potential energy of an electron in an orbital, or is there another meaning behind the number?
No, that's pretty much it. The [Wikipedia entry][1] has a partial periodic table with some $Z_{eff}$ values. If you go further dow... |
In hobby-mycology 70% rubbing alcohol is commonly used for sterilizing work surfaces, bags, syringes, still air boxes, basically everything.
Alcohol however, seems to have some downsides, when it comes to mycology as it needs a long soak time to actually kill anything and it doesn't kill mold and mold spores at all,... |
Is Ammonium chloride suitable for sterilization in mycology? |
(This question is taken from Problem 1.1(b) of the book Chemical Thermodynamics: Principles and Applications.)$\require{begingroup} \begingroup \newcommand{\pd}[3]{\left(\frac{\partial #1}{\partial #2}\right)_{\!#3}}$
> Prove $$\pd HTp = \pd UTV + \left[ V - \pd HpT \right] \pd pTV. \tag{1}$$
First, I expressed $... |
My textbook quotes the following as the limitation of Ellingham diagram:
>The interpretation of $ΔG_f°$(standard Gibbs free energy of formation) is based on $ K $($ΔG_f°=-RT lnK$).Thus it is presumed that the reactants and products are in equilibrium.
Definition of Standard Gibbs free energy of formation:
>The s... |
> Do all noble gases or alkaline earth metals have similar spectral
> lines considering the above points?
The question is interesting after you modified it. The basic set of reasoning you provided is the main story. Each element has a different nuclear charge and the outermost electron(s) is responsible for the ato... |
The alkyl chains of saturated fat molecules can readily rotate about their carbon-carbon single bonds, giving them flexibility and viscosity. What is different about the carbon-carbon double bonds of unsaturated fat molecules, preventing interconversion of cis and trans forms? |
My textbook quotes the following as the limitation of Ellingham diagram:
>The interpretation of $ΔG_f°$(standard Gibbs free energy of formation) is based on $ K $($ΔG_f°=-RT lnK$).Thus it is presumed that the reactants and products are in equilibrium.
Definition of Standard Gibbs free energy of formation:
>The s... |
For the Ellingham diagram:
(1) We write down the reaction/reactions that we are interested in. The $\Delta G_f$ (formation) per mole of product is calculated using the individual free energies of any intermediate reaction, and using Hess' law to sum them up.
(2) This energy is then normalised per mole of $O_2$, u... |
What is the thermal decomposition temperature for SF6? I've heard it decomposes into F2 and SF4 only to decompose further into S2 and F2, but I haven't found much on the topic.
I became curious since I was considering using it to flush out oxygen for some reactions I was doing, due to its density and stability (plu... |
I am not sure what is confusing the original poster. The comments were clear and the answer by Jan is clear. Lets us try to walk you through the problem again.
The question asks about how many milligrams are there in 1 mM caffeine solution. Did you attempt a dimensional analysis?
For mass to mole conversions (or ... |
At breakfast someone asked if the eggs were boiling. While obviously they meant the water for the eggs, but it lead to a discussion regarding if you can make an egg boil without it coagulating or even if you can heat a coagulated egg to the point that it starts boiling under special circumstances such as in an oxygen f... |
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