All Questions
37,455
questions
0
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0answers
5 views
If we consider Uranium-235 , the mass of protons and neutrons combined together is more than the calculated atomic mass of the nucleus . Why is it so?
If we consider U-235 (Uranium-235) , the mass of protons and neutrons in the nucleus combined together is more than the calculated atomic mass of the nucleus . Why is it so ? (Whereas For C-12 (...
0
votes
0answers
4 views
Spurious term in Thomas-Fermi-Hartree energy functional
I am quite a beginner in DFT and I am studying the theory behind the computational tools. I have some doubts about the Columb approximate functional term:
$U[n] = \frac{1}{2} \int d^3 r \int d^3 r^\...
0
votes
1answer
8 views
Enthalpy, heat of solution test: Calcium chloride vs magnesium chloride in water
I did a school experiment to measure the heat of solution (enthalpy) of various salts dissolved in water.
My results are completely different to the teacher's answer.
Specifically my test showed ...
0
votes
1answer
7 views
Formula for rate constant
Please if anyone can help me, I was in a class with my lecturer when he mentioned that the formula for rate constant in first order reaction is this
In which what I know recently is that the rate ...
-1
votes
0answers
3 views
can I measure free chlorine content in treated water using ORP sensor? if yes guide me how?
In my project, I need to measure ph, turbidity, and free chlorine content in treated water from wastewater, I found sensors for ph and turbidity but when I search for chlorine sensor, I found it but ...
2
votes
0answers
10 views
Are there any ADME predictions tools available for Python/RDKit?
Is there any Pythonic way (a.k.a: a module, an rdkit package, etc) or an API I can use for ADME predictions? I need to prioritize some compounds for purchase/synthesis and some sort of ADME scoring ...
-1
votes
1answer
17 views
Why is Cu(II) more stable than Cu(I)? [duplicate]
Seeing Copper has an exceptional electron filling in its valence shell(4s1 3d10), the way I see it is that on +1, a d10 configuration should be more stable and hence easier to attain than a d9 which ...
3
votes
0answers
9 views
Can someone help me understand the motivation behind and visualize the dihedral potential and the Urey-Bradley potential?
I am studying statistical mechanics and force-fields, and I see a lot of this formula being thrown around with no explanation:
$$U_{\mathrm{dihedral}} = \begin{cases}
k(1+\cos (n\psi + \phi)),&...
0
votes
0answers
18 views
Why aren't all the fluorescence transitions the same wavelength?
If all the excited molecules at higher S1 vibrational states rapidly relax to the lowest S1 vibrational state, why do the fluorescence transitions from v' = 1, v' = 2, v' = 3, and other states to v&...
0
votes
0answers
12 views
What Math and chem fields should I study for working with materials science [closed]
I'm coming into my first year at a 4-year university after finishing my associates at a two year school. I think that I am interested in focusing on materials science, I feel like there is still so ...
-2
votes
1answer
26 views
Why do we only take into account the first product while calculating a limiting reactant?
High school chemistry student here. Currently, we are learning stoichiometry and I noticed that when we calculate the limiting reactant of a reaction with multiple products, we almost always just take ...
0
votes
0answers
15 views
Why is there a mirror image effect in the absorbance and fluorescence spectra?
I've read some answers online but I still can't seem to understand the mirror image effect. Why is the highest energy absorption (v" = 0 to v' = 4) the lowest energy fluorescence (v' = 4 to v&...
-1
votes
0answers
8 views
Finding rate constant from a change in pressure experiment
I measured the change in pressure for the decomposition of hydrogen peroxide in the presence of a manganese(IV) oxide catalyst at 5 different temperatures:
$$\ce{2 H2O2 (l) ->[MnO2 (s)] O2 (g) + 2 ...
0
votes
0answers
9 views
Effect of electrolyte on electrolysis of water
Why would concentration of the electrolyte and not the type of electrolyte used affect current density in an electrolytic cell because I believe the mobility of the ion does have an effect on current ...
3
votes
0answers
16 views
Is it feasible to calculate the rate law of the oxidation of ethanol using colorimetry?
My IB Chemistry class needs to have our Internal Assessment ideas finalized by next week, and I'm torn between a few experiments. I'm considering performing an oxidation of ethanol and potentially ...
-2
votes
0answers
16 views
How can someone in the lab synthesize n-allyl-4methyl-benzenesulfonamide from 4-toluenesulfonyl and allylamine
I am trying to figoure out the conditions and choice of solvents and catalysts in order to run this synthesis.
2
votes
1answer
30 views
TEMPO Radical Analogue
After investigating what makes the persistent radical TEMPO stable, I was wondering if another compound which is more feasible for my needs would be comparable to it.
Would oxidizing 2,2’-dimethyl-...
-1
votes
0answers
19 views
Dissipating Cl2
Is there a way to keep Cl2 gas very low in a 55 gallon drum? HOCl is stored in it and there is some Cl2 off gassing in top headspace. Was wondering if there was anything I could use in one of the bung ...
-2
votes
0answers
20 views
Does pressure x volume = kinetic energy?
Sorry don't know if this is more for physics or here, essentially I had a question on the root mean square velocity of gas particles equation and didn't know what it was so tried to work something ...
-1
votes
0answers
17 views
Is there a term for a gel-like substance with a higher concentration of salinity than EO water?
I am writing a story about a planet that is covered in water but the water is closer to a gel-like substance with a higher concentration of salinity than EO water. I just wanted to know if that was a ...
0
votes
1answer
38 views
Finding Kp using log Kp
I am working through some MIT lecture notes trying to understand adiabatic flame temperature. There is a section in these notes where $K_p$ is calculated for the following reaction at $\pu{1600K}$.
$$\...
1
vote
1answer
30 views
Decline in current during electrolysis
I observed a sharp decrease in the current when I carried out the electrolysis of water. Just to set the context, I used a voltage of $\pu{12V}$ and the concentration of my electrolytes were $\pu{0.15 ...
-4
votes
0answers
14 views
I could find the rate of reaction. But am really not able to find the molar mass of the polymer [closed]
Methyl methacrylate was polymerized at a mass concentration of 200 g dm−3 in toluene using
azobisisobutyronitrile as initiator at a mass concentration of 1.64×10−2 g dm−3 and a reaction
temperature of ...
1
vote
0answers
23 views
Hydroboration, steroselectivity and anti-markovnikov product [duplicate]
My first question has to do with the fact that Hydroboration produces an anti-markovnikov product, why?. I don't see how that happens. A wikipedia artical says that B has a partial positive charge ...
-1
votes
0answers
18 views
Effect of electrolytes on the rate of evolution of hydrogen [closed]
What role do ions like $\ce{Ca^{2+}}$ and $\ce{Sr^{2+}}$ as electrolytes play in the electrolysis of water (how do they contribute to current when they don't take part in electrode reactions) and how ...
3
votes
0answers
17 views
Calculating temperature of partial condenser, flash calculations
The iterative method I have learned to make flash calculations for a binary system where I know the inlet feed (F [mol/s]), total composition of the two components ($z_1$ and $z_2$), the amount of the ...
0
votes
0answers
11 views
How to calculate the unknown concentration with delta H and delta S? [closed]
3-ethyl-4-methylhexa-1,3-diene undergoes a combustion reaction. For this reaction, the following
concentrations were used: [O2] = 0.06 M, [CO2] = 0.09 M and [H2O] = 0.10 M. Determine the
concentration ...
-1
votes
0answers
22 views
Dilution confusion
I have run into what I imagined would be simple mathematics, but it turns out I need some help.
My problem is I have a bottle of Geobacillus stearothermophilus and the concentration of the spores is $\...
0
votes
0answers
19 views
Removing denatured Crystalbond?
I have some water-soluble crystalbond that is attached to silicon and, because of some overheating (to about 150 Celcius) during a final processing step, the crystalbond seems to have charred (white/...
-1
votes
1answer
26 views
Is acac- a weak field ligand?
From the chemical structure of acac- compared to NH3 and en, is acac- a stronger or weaker ligand strength? How and why do we know this?
-1
votes
0answers
16 views
Precipitating matals from aqua regia solution [closed]
good day , I have a problem precipitating metals from aqua regia solution that I have made from an ore , it does changes the color when I dip some stannus chloride in to the beaker . But does not give ...
-1
votes
0answers
20 views
Plastic-eating microbes at home
I wanted to know if I can nurture a bacteria which is not difficult to find and with time I can train them on harsh chemicals and soon introduce plastic into it with the hope that it will eat it up ...
-2
votes
0answers
8 views
How to compare experimental results with gas or solvent phase quantum mechanical calculations
I have a question how can we compare gas or solvent phase DFT calculations properties with experimental solid/crystalline phase properties?
How can we validate our theoretical methods?
Thanks,
Shen
0
votes
2answers
50 views
Concept of Equivalent Weight [duplicate]
I'm having a hard time understanding what equivalent weight means physically. I've looked at many articles on Google but the definition always seems nebulous to me.
For example, if the equivalent of $...
-1
votes
0answers
9 views
Estimating enthalpy change of vaporization using bond strengths
If we were to consider the vaporization of liquid water to gaseous water, my instructor stated that it would be "possible to estimate the enthalpy of vaporization based on differences in bond ...
5
votes
2answers
280 views
Why is the base-centered orthorhombic crystal lattice a unique crystal system?
I'm having difficulty understanding why the base-centered orthorhombic crystal system is a unique crystal system. When I draw two base-centered orthorhombic unit cells next to each other there appears ...
-2
votes
0answers
23 views
Why K2CrO4 Potassium chromate is a good oxidizing agent but K2MoO4 Potassium molybdate is not? [duplicate]
although they are in the same group?
Why $\ce{K2CrO4}$ Potassium chromate is a good oxidizing agent but $\ce{K2MoO4}$ Potassium molybdate is not?
0
votes
0answers
40 views
Does 3‐ethyl‐1,1‐dimethylcyclohexane have a stereocenter?
I knew that we have a stereocenter if the carbon is bonded to four different groups.
According to the stereocenter rules, I should have $\ce{CH2}$ bonded to the carbon of the stereocenter (marked with ...
0
votes
0answers
17 views
Removing wood stain from a ceramic surface
I have a bathtub that I accidentally poured wood stain into. Now the stain is all over the white ceramic surface of the tub. I tried using bleach but it didn't do anything. I'm curious if there is a ...
-1
votes
0answers
15 views
How are potential energy curves obtained for diatomic molecules using Hartree-Fock? [closed]
I am looking for a brief explaination on this, or a source that explains this more.
-1
votes
0answers
41 views
Confusion in solution for this Question regarding mole concept
$\pu{48g}$ of graphite and $\pu{16g}$ of $\ce{O2}$ is given. The question is to count the no of molecules of $\ce{CO2}$ produced?
Now, the solution in book is this
No of $\ce{C}$ atoms = $\frac{\pu{...
-2
votes
0answers
24 views
Why ice gets stuck on our hands but cold wood doesn't? [closed]
Is that caused by sweat? Kinda confused.
1
vote
0answers
36 views
phenolsulphonic acid
Phenolsulfonic Acid( PSA) is produced after sulphonation of Phenol at around 100 degrees. They use this product in tinplating.
Once a stable PSA is formed after sufficient reaction , unreacted ...
2
votes
0answers
95 views
Why does titanium have lower affinity than scandium?
Electron affinity of atoms in the same row usually increases with the atomic number until the shell or half-shell gets full, and then it drops down. Some transition metals are exceptions from the rule,...
-1
votes
0answers
24 views
What is the structure of potassium tetraperoxochromate(V)? [closed]
Though some structures are available on the net, different sources are showing different structure, so please share the actual structure of $\ce{K3CrO8}.$
1
vote
1answer
59 views
Comparing O−O bond length in hydrogen peroxide and dioxide(2−) ion
Problem
How can we qualitatively compare the bond lengths between $\ce{H2O2}$ and $\ce{O2^2-}?$
Answer
Attempt
I tried using molecular orbital theory, but since both have peroxide $\ce{O2^2-},$ the ...
3
votes
2answers
31 views
Isobaric entropy relation from isothermal Gibbs free energy relation
I have been given a problem to derive a relation for change in entropy from change in Gibbs free energy:
Starting with the isothermal equation
$$G(p_2) = G(p_1) + nRT\ln\frac{p_2}{p_1}\label{eqn:1}\...
-1
votes
0answers
25 views
How do I solve this protolysis-reaction question? [closed]
I have measured $\mathrm{pH}$-values to these solutions and filled in a table:
$\ce{NaCl}:9.5-10$, $\ce{CH3COONa}:8$, $\ce{Na2CO3}:11.5$, $\ce{NaHCO3}:2$, $\ce{KNO3}:3$, $\ce{NH4Cl}:7-8$
The question ...
-4
votes
0answers
16 views
inverted reverse osmosis reaction products [closed]
Is an inverted reverse osmosis leading to hydride in h2o ?
-1
votes
1answer
23 views
Addition reaction of alkenes
During an addition reaction of an alkene, how does a double bond break to form two bonds with the two atoms of the reactant plus a bond between the carbon atoms? Not sure if this is a silly question ...