All Questions

Filter by
Sorted by
Tagged with
0
votes
0answers
16 views

Enthalpy of formation at other temperatures

I was told each compound has an enthalpy of formation of 0 at the standard temperature if it is in it's lowest energy modification. But what if we change the temperature? It would make sense to me ...
1
vote
1answer
34 views

What is the major product obtained on acidification of substituted epoxide?

The problem Source : MS Couhan (problems in organic chemistry . Chapter: Alcohols , phenols and ethers). My Thoughts If I proceed along $\ce{path 1}$ , $\ce1a$ is formed . It is unstable due to ...
-2
votes
0answers
26 views

How determined the amount of acetic anhydride and pyridine that was added to the polyimide synthesis solution?

I want to synthesis a polyimide from a diamine and a dianhydride in lab scale via polycondensation reaction, in this route in the second step, acetic anhydride and pyridine are added to the reaction ...
3
votes
0answers
22 views

Has there been any independent verification of the results from this Chinese nanotube study?

Watts up referred to the South China Morning Post in reporting that a Tsinghua University team led by Wei Fei claimed in 2018 to have manufactured carbon nanotube fibre has tensile strength of 80 ...
2
votes
0answers
47 views

Why will A atoms diffuse from β phase to α phase and B atoms from α phase to β phase?

At the initial compositions 1 and 2 of $α$ and $β$ respectively the chemical potentials of A and B atoms in each phase can be found by extrapolation of the tangents to the free energy curves at 1 and ...
1
vote
1answer
24 views

Is there a known relation between the diffusion of a molecule and the diffusion of the reactants?

I have a plasma consisting of elements A and B (which have a similar mass). These elements can react to form molecules AB. $$ \ce{A + B -> AB} $$ Now if my plasma or gas is expanding based on ...
-1
votes
0answers
16 views

Does the presence of oxydation agents like O2 prevent the conversion of tert-butanol to isobutylene? [on hold]

In the presence of $\ce{O2}$, does tert-butanol still convert into isobutylene catalyzed by strong acid resin? Do other conditions prevent this conversion? You're actually dealing with tert-butanol, ...
0
votes
0answers
17 views

What metals do not form 1:1 complex with EDTA? [on hold]

Except for group 1A metals, which are very hard acids, what other metals do not form 1:1 complex with EDTA?
-2
votes
1answer
28 views

Why does a system want to achieve randomness to be feasible? [on hold]

According to entropy and gibbs free energy, randomness is one of the factors that determines reaction spontaneity, but why? Shouldn't it be the opposite?
-1
votes
0answers
37 views

What chemical or material could attract plastic?

I'm looking for a material that is affordable, around the 100 USD per kilogram. I'm thinking of a chemical that kind of attracts plastic like a magnet. Microplastics is the type of plastic that I'm ...
-1
votes
0answers
11 views

How can determine galactose and mannose by GC-MS if its elute same RT in 5MS column? We have only galactose standard

How can determine galactose and mannose by GC-MS if its elute same RT in 5MS column. We have only galactose standard and galactose only should quantityfy, but the peak of galactose standard also ...
-3
votes
0answers
19 views

How is the answer for the given question is 1 and not 2nd Option?

The answer should be 2 right? Since as P and V are inversely related. So the PV should be constant.
7
votes
1answer
96 views

In the last step of Kjeldahl Method, is the reaction of ammonium to NaOH not taken into account?

In the last step of Kjeldahl method, the unreacted $\ce{HCl}$ in the solution is back titrated with a standard $\ce{NaOH}$ and the concentration of $\ce{HCl}$ that has been used to neutralize the ...
0
votes
2answers
46 views

Which one has the highest boiling point?

10 g of substance below were dissolve in each 1 L water: $\ce{Na2SO4}$ $\ce{NaCl}$ Glucose $\ce{MgCl2}$ Which one has the highest boiling point? Glucose has London dispersion force. $\...
0
votes
1answer
41 views

What causes positive and negative deviations when weighing analytical samples?

Positive deviations are when the measured mass is more than the true mass of the sample and negative deviations are when the measured mass is less than the true mass of the sample. What steps causes ...
-1
votes
0answers
7 views

Coordination Bond of metal nanoparticles [on hold]

Silver nanoparticles form coordination bond with cationic site at room temperature?
0
votes
0answers
18 views

pKa values for amino acid

To calculate the pI value, we take the average of the pKa values from the 2 groups that result in a net charge of 0. For that to happen, the pKa values should be at the midpoint of titration where ...
0
votes
0answers
10 views

What causes the duration of the amber periods of the Briggs-Rauscher reaction to first increase and then decrease as the reaction oscillates?

I was collecting experimental data on the Briggs Rauscher reaction and realized that the period of the amber oscillations initially decreased and then started to increase. While I understand the ...
2
votes
1answer
31 views

Antibonding, Nonbonding and Bonding orbitals

Recently I came across nonbonding orbitals. I know something about bonding and antibonding orbitals and their formation, but I have no idea about nonbonding orbitals. Could someone explain their ...
2
votes
1answer
51 views

Is it possible to produce sodium bicarbonate from potassium bicarbonate?

I balanced the chemical reaction which is as follows: NaCl + KHCO3 = NaHCO3 + KCl I've also gathered solubility values which are the following: KHCO3 22.4 g/100 mL (20 °C) NaCl 35,9 g/100 mL (20°) ...
2
votes
3answers
254 views

If Beer's Law appears to apply to a high concentration (>0.01M) of a solute, is it valid to use for concentration calculation?

Internet consensus seems to define "high concentration" for Beer's Law as >0.01M. If one has a solution at higher concentrations than that, but the absorbance vs. concentration is still linear, is it ...
-1
votes
1answer
17 views

Equilibrium Constant dependence

The equilibrium constant (EC) of a certain reaction is only dependent on temperature. For instance, suppose at a certain temperature, the EC of $\ce{A + 3B <=> 2C}$ is $K$. Now if I divide the ...
-1
votes
0answers
18 views

Problem with the wave intensity graph of a blackbody [on hold]

I recently read about the ultraviolet catastrophe. What does the graph of lambda vs intensity represent? Is it the intensity of each light wave of each wavelength at a certain temperature or something ...
2
votes
1answer
57 views

How to calculate molecular emission spectra? [on hold]

Is there free software which can calculate the fluorescence emission spectra of organic molecules? Let's say for example: rubrene There is a bunch of quantum free quantum chemistry software: https://...
0
votes
0answers
29 views

Conditional kinetic equations

From a biological system, I got the following reaction: $$A+B+D\rightarrow C+C_1D$$ ($C_1D$ is a certain complex) However, if at any given time there are no $D$s to react, and only then, instead the ...
3
votes
0answers
16 views

Why doesn't the Pilling-Bedworth ratio of silicon cause issues in silicon technology?

According to Wikipedia, silicon has a Pilling-Bedworth ratio of 2.15. In theory this should mean an SiO2 film on silicon should have a fairly large amount of compressive stress and high probability of ...
-4
votes
0answers
17 views

What would happen if you swallow NAC and Acidophilus pills right after taking alcohol? [on hold]

You drink 30 grams of 40% rum with few ounces of water and then swallow a few supplements that are supposed to be taken on an empty stomach. NAC and Acidophilus. Besides the water and alcohol, the ...
-2
votes
0answers
24 views

Is isobutane found in the organic or aqueous layer of a sep. funnel? [on hold]

Is isobutane found in the organic or aqueous layer of a sep. funnel?
14
votes
3answers
2k views

Why does a tetrahedral molecule like methane have a dipole moment of zero?

I was studying chemical bonding when I noticed something odd. We say compounds like $\ce{CCl4}$ and $\ce{CH4}$ have a tetrahedral geometry (which is a 3D structure) but when we talk about their ...
2
votes
1answer
46 views

How is the 'rate law' and 'order' for the ozone decomposition reaction can be defined?

How is the 'rate law' and 'order' for the following reaction can be defined? $$\ce{2O3 -> 3O2}$$ "The expression that correlates the rate of reaction with concentration of reactants is known as ...
-3
votes
0answers
34 views

Rate Constant (Equilibrium constant)

I am struggling to find the values for equilibrium constant ($K$) and forward reaction rate constant ($k_f$)for the following: $$\ce{2Fe^3+ + 3H2O <=>Fe2O3 +6H+}$$ and the rate of dissolving ...
0
votes
1answer
74 views

What is the reason for phase separation? [on hold]

I have seen phase separation as a phenomenon taking place. However I do not understand why this phenomenon occurs as a counter example to the natural laws of diffusion along the concentration gradient....
6
votes
0answers
23 views

Identifying Name/Purpose of piece of ellipsoid glassware with internal tube?

I recently went to a market in Southern France and found this little piece of equipment for sale along with a whole bunch of other chemistry things. the guy had no idea what it was for or where he'd ...
-1
votes
0answers
7 views

Compare the polarity of sulphur dioxide and suphite ion [on hold]

Can anyone tell me,sulphur dioxide,SO2, and suphite ion,SO3 2-,which one is more polar and why?
2
votes
2answers
100 views

Does energy come from fuel or oxygen? (surprise?)

Question: Is it oxygen or fuel that releases energy during burning? The answer from this article: Why Combustions Are Always Exothermic, Yielding About 418 kJ per Mole of O2 (Journal of Chemical ...
1
vote
0answers
16 views

Choice of buffer pH to avoid aggregation

I want to purify IgG which has a theoretical pI of 6.4-9.0 with an anion exchange column. I also want to keep the pH of my buffers as low as possible and "outside" the range of the pI to prevent ...
-2
votes
2answers
105 views

How to calculate the number of atoms in a gas molecule?

$\pu{20 mL}$ of sulfur vapour at $\pu{1000 °C}$ reacts with $\pu{40 mL}$ of oxygen gas to form $\pu{40 mL}$ of sulfur dioxide gas. Determine the number of atoms in the molecule of sulfur in the vapour ...
1
vote
0answers
26 views

In situ preparation of Potassium Tert-Butoxide

I am attempting to prepare potassium tert-butoxide. I was going to suspend anhydrous toluene and anhydrous tert-butanol, dissolve (reflux) the potassium metal (pure), then distill the excess tert-...
1
vote
1answer
35 views

Balance Repeatability Sample or Population for SD

A question for the masses about standard deviation (SD), selection of population vs sample in balance measurements. Analytical balances are typically checked for repeatability by taking 10 weight ...
0
votes
0answers
12 views

Catalyzing the breakdown of Si-O bonds

What catalysts can catalyze the breakdown of (Si-O) bond ? Can you mention some books(ebooks or hard cover) or websites that cover a lot of information about (Si-O) bond characteristics? I have ...
-1
votes
0answers
20 views

partially cancelling spectator ions

Is it possible to partially cancel spectator ions? Suppose in the ionic equation the same ion appears on both sides but with different coefficients.
1
vote
0answers
20 views

What lubricant can be used for mechanical parts in a system containing diethyl ether?

I make a thermal actuator that works with the expansion of diethyl ether at its boiling point of around 34 °C. For sealing and lubrication of the polypropylene piston and barrel, I need a lubricant ...
0
votes
1answer
56 views

Radial Probability Distribution Curve versus ψ² versus r curve for 1s orbitals

My question is basic, but I have already referred to a couple of books. This is an excerpt from Linus Pauling's book: the most probable distance of the electron from the nucleus, which is the ...
2
votes
1answer
49 views

Miller indices: How does one translates the orientation to the origin of the unit cell?

In a section discussing Miller indices, my textbook says the following: The rules for determining the Miller indices of a direction or an orientation in a crystal are as follows: translate the ...
2
votes
1answer
51 views

Looking for a radio-transparent epoxy/resin

I have much hobby experience with 2-part resins, but this time I'm looking to make a repair part for the inside of a microwave oven (everything I've tried so far heats up, but the original part does ...
1
vote
1answer
34 views

Usage of TFA in Pfitzner-Moffat oxidation and Collins vs Jones oxidation

Is the addition of TFA in Pfitzner-Moffat oxidation to protonate the DCC to form a positive carbocation for the alcohol to attack? Or is there more to it? Why is TFA used and not other acids? Are ...
1
vote
1answer
36 views

Why do we use hydrochloric in the test for sulfate ions but nitric acid for halide ions?

Recently, I have learnt about testing for ions in qualitative analysis (BBC Bitesize). The link above which I used for reference mentions that for the test for sulfate anions, hydrochloric acid $(\ce{...
0
votes
1answer
40 views

Lowering the melting point of water with salt

I was trying to calculate amount of salt needed to lower the melting point of water by 5 °C. According to my solutions, I need to make sure $$n\mu(\ce{H2O(s)}) =n\mu(\ce{H2O(l)})+ RT\log(x)$$where $ x=...
0
votes
1answer
29 views

How can spike recovery be over 100%?

I am confident enough about my knowledge about spiking and the process of standard addition but I came across this process which claimed to have a percent recovery of 115% and it was considered as a ...
-1
votes
0answers
23 views

Speeding up the rusting/oxidation process of various metals using ferric chloride? [on hold]

So I have ferric chloride etching solution here is the datasheet for the product I have: https://download.altronics.com.au/files/datasheets_H0800D.pdf I have 4 types of metal; stainless steel metal, ...

15 30 50 per page