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In the book of *Molecular Cell Biology* (Big Alberts) by Alberts, at page 46, it is stated that
> Acids—especially weak acids—will give up their protons more readily if the concentration of > H3O+ in solution is low and will tend to receive them back if the concentration in solution is high.
Does this mean that,... |
How much D2O is in Vienna Standard Mean Ocean Water? |
I've encountered in chemistry quite a lot of reducing agents. However one question strikes me quite often and any research done on the same hasn't been fruitful. This is in context to organic chemistry. Now for example, in reductive ozonolysis, we often use ozone in combination with zinc and water. Zinc's presence ens... |
## General Case
This question concerns the general problem of accurate volume measurement of a given object. Among other techniques, that of liquid displacement is sometimes used for this purpose.
- In case of a **solid material**, the latter may be immersed in liquid, and its volume calculated by measuring t... |
Cl in HCL has three lone pairs of electrons. So it can donate a lone pair and thus become a lewis base. Right ? Just like water is called a lewis base because Oxygen has 2 lone pairs and can donate a lone pair. |
Why is HCl not a lewis base? |
If you add **NaOH to D-glucose** in water, a mixture of almost **all aldohexoses** will arise over time, including **mannose** and **fructose**. I wonder how much of each will be present and what could explain the distribution. My assumption is that the amount will match stability and that the most stable D-beta-glucos... |
If you add **NaOH to D-glucose** in water, a mixture of almost **all aldohexoses** will arise over time, including **mannose** and **fructose**. I wonder how much of each will be present and what could explain the distribution. My assumption is that the amount will match stability and that the most stable D-beta-glucos... |
Cl in HCl has three lone pairs of electrons. So it can donate a lone pair and thus become a lewis base. Right? Just like water is called a lewis base because oxygen has 2 lone pairs and can donate a lone pair. |
Is HCl a lewis base? |
I want to ask a question about working out the energy of a hydrogen bond between two water molecules, $w_{AA}$ using the chemical potentials of vapour and condensed phases.
I was reading K. Dill, Molecular Driving Forces, 2nd Ed, 2011, p. 257 which lines out the framework for the Clapeyron equation and I was confus... |
I'm extremely confused about work done on a gas. So if you look at the system pictured,
[![System Being Discussed][1]][1]
[1]: https://i.stack.imgur.com/Bbgtv.png
From what I've read online, the net work done, which is equal to the work done by the objects, is equal to the pressure times the change in vol... |
Work done on a Gas? |
You have differential equations.
Differential equations are ALL about the initial conditions, and A PROCESS.
- So, what’s the initial condition?
You have a piston with a given volume of gas.
- What’s happening then?
I apply an additional force with an object. (The atmospheric pressure already was the... |
Using the mass of $\ce {CaCO_3} (\pu{0.500 g})$, what volume of $\ce {CO_2} (\pu{mL})$ could theoretically be obtained if the reaction progressed to completion. Assume that the pressure was $\pu{101.3 kPa}$ and the temperature was $\pu{22.5^\circ C}$ and that the gas was behaving ideally. $(R = \pu{8.314 kPa L mol-1 K-... |
In Energy-Dispersive X-ray Spectroscopy, do higher atomic elements ever generate just K lines without L or M lines? |
So hypothetically, if one was to buy Krypton and wanted to make it glow would a little tesla coil be enough to make it glow? If not, what would be enough? And would one be able to make it glow multiple times or just once, like will making it glow wear down the electrons in the Noble gas or somethin’? |
Great question! I don't believe it'll wear out in the short term. Light is produced when the electron is excited to a higher orbital and drops back down; this is completely reversible. Neon tubes work on the same principle and last for years!
*Eventually* (probably after many years) a whole bunch of effects will pro... |
Using the mass of $\ce {CaCO_3} (\pu{0.500 g})$, what volume of $\ce {CO_2} (\pu{mL})$ could theoretically be obtained if the reaction progressed to completion? Assume that the pressure was $\pu{101.3 kPa}$ and the temperature was $\pu{22.5^\circ C}$ and that the gas was behaving ideally. $(R = \pu{8.314 kPa L mol-1 K-... |
Using the mass of CaCO3, what volume of CO2 could theoretically be obtained if the reaction progressed to completion? |
> Using the mass of $m(\ce{CaCO3}) = \pu{0.500 g}$, what volume of $\ce{CO2} (\pu{mL})$ could theoretically be obtained if the reaction progressed to completion? Assume that the pressure was $\pu{101.3 kPa}$ and the temperature was $\pu{22.5 ^\circ C}$ and that the gas was behaving ideally. $(R = \pu{8.314 kPa L mol-1 ... |
Using the mass of calcium carbonate, what volume of carbon dioxide could theoretically be obtained if the reaction progressed to completion? |
> Using the mass of calcium carbonate $m(\ce{CaCO3}) = \pu{0.500 g}$, what volume of carbon dioxide $V(\ce{CO2})$ (in $\pu{mL})$ could theoretically be obtained if the reaction progressed to completion? Assume that the pressure was $\pu{101.3 kPa}$ and the temperature was $\pu{22.5 ^\circ C}$ and that the gas was behav... |
I think the problem is you're thinking of it the wrong way, that is, you first think that $ q= nC_p \Delta T$ and for constant pressure process $q_p= \Delta H$ , and hence, $ \Delta H = nC_p \Delta T$
In actuality, it is the other way around. Similar to how internal energy is always $nC_v \Delta T$, the enthalpy is ... |
My friend and I are trying to synthesize mercury thiocyanate, however the only reagents we have access to are mercuric acetate and ammonium thiocyanate.
We figured that we could possibly force a substitution reaction with these reagents in alcohol over heat with stirring.
It worked, but after a few moments the so... |
Most likely, vanadium cannot exist as a 4+ or 5+ ion except as part of a covalently bound species such as $\ce{VO^{2+}}$ or $\ce{VO2^+}$. However, its heavier congeners niobium and tantalum form minerals whose structure indicates at least partial ionic bonding in the +5 oxidation state. One such mineral is [Schiavina... |
> Why wouldn't the net work done on the gas be equal to the work done on both the gas and the atmosphere, which is also applying a force on the gas?
Your phrasing is almost correct: The work done *on* the gas in the cylinder is equal to the work done *by* the atmosphere (if any) plus the work done *by* the lowering... |
> Why wouldn't the net work done on the gas be equal to the work done on both the gas and the atmosphere, which is also applying a force on the gas?
Your phrasing is not quite correct: The work done *on* the gas in the cylinder is equal to the work done *by* the atmosphere (if any), plus the work done *by* the lowe... |
To save soap during this pandemic, I mixed foaming soap of two different brands and then the solution became cloudy (both originally transparent) . It seems foaming okay. But does this make the soap less efficient in washing away germs/virus? Does the foaming show that the mixture is still working as a regular soap?
... |
Does mixing two different foaming soap make it ineffective? |
**Disclaimer** : The below discussion only holds to be completely true for reversible processes.
I think the problem is you're thinking of it the wrong way, that is, you first think that $ q= nC_p \Delta T$ and for constant pressure process $q_p= \Delta H$ , and hence, $ \Delta H = nC_p \Delta T$
In actuality, it... |
First off, I'm not *actually* trying to blow anything up. Also, my apologies if this isn't the right SE to ask. If so, I'd appreciate it if you could point me to the right SE.
I'm writing something where at a point I need a big explosion to happen. I've done some digging and I found out that the old bullet-fired-at-... |
I'm extremely confused about work done on a gas. So if you look at the system pictured,
[![System Being Discussed][1]][1]
[1]: https://i.stack.imgur.com/Bbgtv.png
From what I've read online, the net work done, which is equal to the work done by the objects, is equal to the pressure times the change in vol... |
So hypothetically, if one was to buy krypton and wanted to make it glow, would a little tesla coil be enough to make it glow? If not, what would be enough? And would one be able to make it glow multiple times or just once, like will making it glow wear down the electrons in the noble gas or somethin’? |
I understand that Water Bottles expire due only to the fact that the plastic can degrade over time and leach into the water making the water's taste not as desirable as the manufacturer might intend.
Does anyone happen to know the degradation rate/expiration for #4 LDPE? I'm using a plastic water storage vessel for ... |
Does #4 LDPE Plastic Bottle Leach into Water? |
I know of this ring expansion reaction that can fuse a benzene ring with another benzene ring:
[![naphthalene from benzene][1]][1]
Performing this reaction twice gives us phenanthrene
[![phenanthrene from benzene][2]][2]
**How would one go about synthesizing pyrene from phenanthrene or benzene**? I couldn't... |
**Disclaimer**: The below discussion only holds to be completely true for reversible processes and for ideal gases.
I think the problem is you're thinking of it the wrong way, that is, you first think that $ q= nC_p \Delta T$ and for constant pressure process $q_p= \Delta H$ , and hence, $ \Delta H = nC_p \Delta T$
... |
Your question reminds me to [Nixie tubes][1]. Well, while these _typically_ deploy Ne and Ar (e.g. in the Czech republic, [Dalibor Farny][2], [documentation video][3]). But there are [Penning _mixtures_][4] for Krypton, too, as described e.g. by Heylen in 1985 in the _International Journal of Electronics_ ([doi 10.108... |
O-formyl benzoic acid or p- formyl benzoic acid. Which is more acidic? |
Your question reminds me to [Nixie tubes][1]. Well, these _typically_ deploy Ne and Ar (e.g. in the Czech republic, [Dalibor Farny][2], [documentation video][3]). But there are [Penning _mixtures_][4] for Krypton, too, as examined e.g. by Heylen in 1985 in the _International Journal of Electronics_ ([doi 10.1080/00207... |
Consider a process in which state variables changes from $(p_1, V_1, T_1)$ to $(p_2, V_2, T_3)$ . I've learned that to calculate the change in enthalpy for any process, we consider a hypothetical isobaric process (Since enthalpy is a state function, it doesn't depend on the path).
Should the hypothetical process hav... |
Consider a process in which state variables changes from $(p_1, V_1, T_1)$ to $(p_2, V_2, T_3)$ . I've learned that to calculate the change in enthalpy for any process, we consider a hypothetical isobaric process (Since enthalpy is a state function, it doesn't depend on the path).
Should the hypothetical process hav... |
In a mass spectrometer the sample is vapourised, then ionised, then accelerated.
My textbook says that the high energy electrons from the electron gun knock electrons off the sample molecules and hence ionise the particles by 1+.
But do some particles get 2 or more electrons knocked out or is it always just one ?... |
Do some particles get ionised to 2+ or higher in a mass spectrometer or do they only get ionised to 1+? |
I read somewhere that hydrogen cation combines with water to form hydronium ion. I also read it combines with various water molecules. Can someone please explain? |
I found the pH of alanine solution, and I need its concentration, I'm given the formula below:
pH=1/2(PKs-Log Cs))
My try:
i have calculated pH, to find Cs I need PKs, can someone explain that formula, what is PKs? I know that this amino acid has Pka1 and Pka2, which do I use?
thanks a lot |
Concentration of Amino acid calculation? |
**Disclaimer**: The below discussion only holds to be completely true for reversible processes and for ideal gases.
I think the problem is you're thinking of it the wrong way, that is, you first think that $ q= nC_p \Delta T$ and for constant pressure process $q_p= \Delta H$ , and hence, $ \Delta H = nC_p \Delta T$
... |
I an getting confused between enthalpy and internal energy. My textbook says that change in enthalpy is the sum of change in internal energy and the amount of work done in expansion or compression but isn't it the same as the amount of heat lost or given. So why do we need enthalpy? |
What is the significance of enthalpy? |
I found the $\mathrm{pH}$ of alanine solution, and I need its concentration, I'm given the formula below:
$$\mathrm{pH}=\frac 12 (\mathrm{p}K_\mathrm{a}- \log c)$$
My try:
I have calculated $\mathrm{pH}$, to find $c$ I need $\mathrm{p}K_\mathrm{a}$. Can someone explain that formula, what is $\mathrm{p}K_\mathr... |
I know that free energy is defined as the amount of work that a system can do at constant temperature and and its formula is F=U-TS and that by definition Helmholtz free energy is the amount of work a system can do at constant temperature and constant volume but the formula is still A=U-TS. Why is that , why is there n... |
I’m attempting to perform an Iodometric redox titration to evaluate the vitamin c concentration in a particular solution. These solution have dissolved within them up to 2% cellulase enzyme.
In an iodometric redox titration, a 0.5% starch indicator solution would be used to inform when endpoint occurs via it’s reacti... |
Does cellulase catalyze the hydrolysis (or break down) of soluble starch? |
When you calculate the equilibrium constant for a reaction with a higher concentration of reactants, the answer is fairly intuitive. For example, for the reaction:
$$\ce{A + B <=> C}$$
Where we have $0.10 M$ of A, $0.30 M$ of B and $0.45$ M of C the equation for the equilibrium constant is:
$$ K = \frac{[0.45]... |
What does the equilibrium constant mean for reactions with very small concentrations? |
To save soap during this pandemic, I mixed foaming soap of two different brands and then the solution became cloudy (both originally transparent) . It seems foaming okay. But does this make the soap less efficient in washing away germs/virus? Does the foaming show that the mixture is still working as a regular soap?
... |
To save soap during this pandemic, I mixed foaming soap of two different brands and then the solution became cloudy (both originally transparent) . It seems foaming okay. But does this make the soap less efficient in washing away germs/virus? Does the foaming show that the mixture is still working as a regular soap?
... |
> How to get a better turnover while maintaining a reasonably short reaction time?
To speed up the reaction, you should look at changing (1) the reagents, (2) the catalysts, or (3) the reaction conditions. In particular you might be dealing with poor solubility for your alkyne substrate if you are doing the reactio... |
[IR spectrum][1]
[1]: https://imgur.com/a/OCHXCzL
Is it safe to say that this IR spectrum belongs to a carboxylic acid because of the 3100-2700 stretch indicating OH group, and the sharp peak at 1728 showing a carbonyl group? |
Am I understanding this IR spectrum correctly? |
Suppose you have a single atom, say carbon, carbon has six electrons, and six protons. Now is there anything associating the six protons locking the six electrons other than coulombic forces?
When we ionize a compound, we remove the electron from the outermost shell. Now I find this weird because, from my understan... |
For example, this reaction is a dehydration reaction
$$\ce{ HNO3 + P4O10 -> N2O5 + HPO3} $$
If I were only given the reactants side of the equation, how would I predict the product's side of it?
What I have seen already:
https://chemistry.stackexchange.com/questions/50684/how-can-i-predict-if-a-reaction-will-... |
> 'x' grams of benzene and 'y' grams of toluene, it is said that the vapor pressure of benzene is 75 mmHg and that of toluene is 22 mmHg. Find mole fraction in the vapor state,
What I do not understand is how different states can have different values for mole fraction? Do the moles change with a change of state?
... |
When we make an electrochemical cell, we dip the electrodes in the salt solution. How exactly does the electrode potential change as we dip the electrodes in the salt solutions? |
>The $E^θ(\ce{M^{2+}}/\ce{M})$ value for copper is positive ($\pu{+0.34 V}$). What is possibly the reason for this? (Hint: consider its high $Δ_aH_V$ and low $Δ_{hyd}H_V$)
We know that we have to first break the metallic lattice to turn the metal into gas and hence there should be some sort of relation between the... |
Which is the correct structure of $\ce{NO2}$? While searching the internet I found out that
1. $\ce{NO2}$ have a coordinate and two covalent bonds. $\ce{N}$ will have a positive charge. $\ce{O}$ (coordinate bond) will have a negative charge (this is the part which I don't understand. As $\ce{O}$'s octet is complet... |
When we make an electrochemical cell, we dip the electrodes in the salt solution. How exactly does the electrode potential change as we dip the electrodes in the salt solutions? Would different salt solutions change the effect of the electrode potential? |
I want to give students the chance to gently waft and smell HCl.
What concentration would be considered safe for a once-off single waft and smell ?
|
What concentration of HCl is safe to smell? |
I calculated this:
molar mass (M) of Mg(NO3)2 is 148,32 (24,3 + 2*14,01 + 6*16)
so when there is 7 grams Mg(NO3)2 there is 0,0472 mol (7/148,32)
But how do i find out how much of that is oxygen? Do i just divide by 8 and multiply by 6? (because 8 atoms of with 6 are oxygen) |
How much grams oxygen is in 7 gram magnesiumnitrate? Mg(NO3)2 |
I read that silver in the presence of hydrogen sulphide corrodes to form silver sulfide.
$$Ag + H_2S \rightarrow AgS+ H_2$$
But in the reactivity series silver is much placed below hydrogen.
So, how it this displacement reaction taking place at all? |
I read that silver in the presence of hydrogen sulphide corrodes to form silver sulfide and hydrogen.
$$Ag + H_2S \rightarrow AgS+ H_2$$
But in the reactivity series silver is much placed below hydrogen.
So, how is this displacement reaction taking place at all? |
Everywhere I look it just states that $\ce{MnO2}$ acts as a catalyst but I have yet to find a simple explanation for what it actually does. What is the mechanism involved in simple terms ? |
When $\ce{MnO2}$ acts as a catalyst to speed up the decomposition of $\ce{H2O2}$ what does the $\ce{MnO2}$ actually do? |
I read [here][1] that silver in the presence of hydrogen sulphide corrodes to form silver sulfide and hydrogen.
$$Ag + H_2S \rightarrow AgS+ H_2$$
But in the reactivity series silver is much placed below hydrogen.
So, how is this displacement reaction taking place at all?
[1]: https://pubs.acs.org/doi/abs/10.102... |
Everywhere I look it just states that $\ce{MnO2}$ acts as a catalyst but I have yet to find a simple explanation for what it actually does. What is the mechanism involved in simple terms? |
When MnO2 acts as a catalyst to speed up the decomposition of H2O2 what does it actually do? |
I read [here][1] that silver in the presence of hydrogen sulphide corrodes to form silver sulfide and hydrogen.
$$\ce{Ag + H2S -> AgS + H2}$$
But in the reactivity series silver is much placed below hydrogen.
So, how is this displacement reaction taking place at all?
Reference: _J. Chem. Educ._ 2000, 77, 3,... |
What is the change in enthalpy for an adiabatic expansion? |
The limit of detection for an analytical method can be derived from its calibration curve using the following equation:
$$ LOD = {\dfrac{(3.3 \cdot {\sigma_{resids}})} {m}} \tag{1} $$ [see reference at bottom]
where:
- $ \sigma_{resids} $ is the standard deviation of the residuals of the regression fit
- $m... |
As a teacher, you should _lead by example_ how to engage with chemicals respectfully, as a professional. Which neither is to be fearful, nor to be sloppy and negligent for their _potential hazards_. This includes to plan ahead, to limit exposure to dangerous goods (like concentrated HCl is), to use protective gear, sa... |
[![enter image description here][1]][1]
Is it safe to say that this IR spectrum belongs to a carboxylic acid because of the 3100-2700 stretch indicating OH group, and the sharp peak at 1728 showing a carbonyl group?
[1]: https://i.stack.imgur.com/ZYtJO.png
[2]: https://imgur.com/a/OCHXCzL |
The limit of detection for an analytical method can be derived from its calibration curve using the following equation:
$$ LOD = {\dfrac{(3.3 \cdot {\sigma_{resids}})} {m}} \tag{1} $$ [see reference at bottom]
where:
- $ \sigma_{resids} $ is the standard deviation of the residuals of the regression fit
- $m... |
I am reading the paper:
**Petersheim, M. and Turner, D.H. (1983) Base-stacking and base-pairing contributions to helix stability: thermodynamics of double-helix formation with CCGG, CCGGp, CCGGAp, ACCGGp, CCGGUp, and ACCGGUp. Biochemistry, 22, 256-263.**
What does the **p** at the end of the sequence stand for? W... |
I am reading the paper:
**Petersheim, M. and Turner, D.H. (1983) Base-stacking and base-pairing contributions to helix stability: thermodynamics of double-helix formation with CCGG, CCGGp, CCGGAp, ACCGGp, CCGGUp, and ACCGGUp. Biochemistry, 22, 256-263.**
The **p** at the end of the sequence apparently stands for ... |
While reading my NCERT chemistry book (Pg no.-300), I came across a table that mentions colors emitted by alkali metals and corresponding wavelengths.[![Here's a picture from my book.][1]][1] It mentions that Potassium emits violet color(As far as I know it's more close to lilac) but corresponding wavelength written ... |
I read that silver in the presence of hydrogen sulphide corrodes to form silver sulfide and hydrogen.
$$\ce{Ag + H2S -> AgS + H2}$$
But in the reactivity series silver is much placed below hydrogen.
So, how is this displacement reaction taking place at all?
Reference: _J. Chem. Educ._ 2000, 77, 3, 328A; [do... |
The limit of detection ($LOD$) for an analytical method can be derived from its calibration curve using the following equation:
$$ LOD = {\dfrac{(3.3 \cdot {\sigma_
\mathrm{resids}})} {m}} \tag{1} $$ [see reference at bottom]
where:
- $ \sigma_\mathrm{resids} $ is the standard deviation of the residuals of t... |
I have been reading about introductory Molecular Orbital Theory lately. Till now, I have used Valence Bond Theory to evaluate bonding. I have a few questions about it:-
1. In VBT, we used the idea that bonds form when orbitals overlap. In Oxygen molecule, two bonds forms in VBT as the other orbitals were far enough ... |
## General Case
This question concerns the general problem of accurate volume measurement of a given object. Among other techniques, that of liquid displacement is sometimes used for this purpose.
- In case of a **solid material**, the latter may be immersed in liquid, and its volume calculated by measuring t... |
I recently received some lab results from a sample which contained a lot of CO2, which degassed before the total alkalinity was measured by titration to a pH 4.5 end point. The best analogue for this sample would be a carbonated (sparkling) mineral water, which was measured 5 min after opening the bottle.
Is the tot... |
For example, at lower amounts of silver the alloy gets stronger due to precipitation hardening, so in the composition as the wt% of silver increases how do the mechanical properties change? Both of them are FCC structure, so does the ductility remain the same as well? |
Does the lamellar structure in say a copper-silver phase diagram have any unique mechanical properties? |
Does the term only refer to molecules that have the same symmetry elements or exactly the same symmetry operations. Online I see that its the same symmetry operation however my professor's slides show only symmetry elements.
Or is it depend on the writer; Dnh refers only to symmetry elements but D3h refers to symme... |
From what I know, good inorganic chlorinating agents, $\ce{SOCl2, PCl3, PCl5}$ are able to substitute a poorer leaving group (like $\ce{OH-}$) for chlorine. For example, for substitution of the hydroxyl group to a halide to form a haloalkane, we can't just use hydrogen halides (we can if we first dehydrate it into an a... |
What makes a good chlorinating agent? |
I read that silver in the presence of hydrogen sulfide corrodes to form silver sulfide and hydrogen.
$$\ce{Ag + H2S -> AgS + H2}$$
But in the reactivity series silver is placed much below hydrogen.
So, how is this displacement reaction taking place at all?
Reference: _J. Chem. Educ._ 2000, 77, 3, 328A; [doi... |
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