All Questions
44,970
questions
6
votes
2
answers
29k
views
Why is maltose a reducing sugar but not sucrose, even though they're both disaccharides?
I came across this on Wikipedia:
Many disaccharides, like cellobiose, lactose and maltose, also have a reducing form, as one of the two units may have an open-chain form with an aldehyde group. ...
- 18.7k
2
votes
0
answers
889
views
Calculating the pH of buffer solution made of two salts of a polyprotic acid
When we are making a buffer solution by solutions of a weak acid and its salt like $\ce{CH3COOH}$ and $\ce{CH3COONa}$, or by a weak base and its salt like $\ce{NH3}$ and $\ce{NH4Cl}$, we can use the ...
- 5,675
5
votes
2
answers
4k
views
Do the products in exothermic reactions have higher kinetic energy than the products? Do they also have lower chemical energy?
I understand that in an exothermic reaction energy is transferred to the surroundings. More energy is produced from making bonds than absorbed to break bonds.
I would imagine that the products have ...
- 121
1
vote
2
answers
2k
views
Reactivity of Alkanes
Does the tetrahedral structure of the alkanes contribute to their lower reactivity? I thought that because a tetrahedral structure suggests ${sp^3}$ hybridization, it should contribute to its lower ...
-1
votes
1
answer
5k
views
Why do noble gases, although not molecules, use London dispersion forces? [closed]
Why do noble gases, although not molecules, use London dispersion forces?
2
votes
1
answer
2k
views
Solving for H+ given dissociation of weak acid, c and Ka Can the quadratic equation yield two nontrivial solutions?
For example, if a question asks for $[\ce{H+}]$ of a $0.100~\mathrm{M}$ solution of picric acid (monoprotic), given that its $K_\mathrm{a}$ at the system temperature is $4.2 \times 10^{-1},$ following ...
- 399
-1
votes
2
answers
7k
views
Why is the manufacture of sulfuric acid known as the contact process? [closed]
I was after some detail as to why the contact process was named as such.
- 117
-1
votes
1
answer
7k
views
Are hydrogen bonds stronger than ionic bonds? [closed]
What is the order of strongest bonds to weakest? Are hydrogen bonds stronger than ionic bonds? Are hydrogen bonds covalent bonds?
- 1
8
votes
1
answer
692
views
How to prevent water from abandoning solvent box during molecular dynamics simulation with AMBER?
I ran a molecular dynamics simulation for a small polypeptide and TIP3P water with AMBER using solvatebox function with with a distance of 15 Å between the molecule ...
- 6,722
6
votes
1
answer
282
views
What advantage is there in reporting the Lennard-Jones well depth in wavenumber units?
The Lennard-Jones well depth $\epsilon$ is typically given in energy units ($\mathrm{kJ}$ or $\mathrm{kcal}$; sometimes per mole). Jasper and Miller, however, reported $\epsilon$ values in reciprocal ...
- 4,257
-1
votes
1
answer
146
views
What is the final product of a carbohydrate treated successively with hydrogen cyanide, water, and hydrogen iodide/ phosphorus?
An unknown carbohydrate is successively treated with (1) hydrogen cyanide, (2) water, and (3) hydrogen iodide and phosphorus:
$$\ce{C6H12O6 ->[HCN] X ->[H2O] Y ->[HI,P]Z}$$
What is the ...
- 2,143
1
vote
0
answers
428
views
Fast and complete ways to remove chloride from solution (sub ppb levels)
Main question: We are trying to reduce the chloride concentration in a solution to sub-ppb levels. I have to dissect a fruit fly in this solution so I am interested in removing any chloride that is ...
3
votes
1
answer
883
views
Why does ammonia "clean" scratches?
I read that ammonia can be used to clean scratches of certain materials, for example from wedding rings. I was thinking about how this would work but I actually don't know. I suspect that the question ...
- 133
0
votes
1
answer
3k
views
How is graphite a covalent solid?
I know it is covalent because there are covalent bonds between atoms of carbon in the same plane. But there are Van der Waals interactions between different planes. Isn't this a feature of molecular ...
- 289
5
votes
2
answers
853
views
How this tricky Wagner-Meerwein rearrangement occurs?
In 1979, Karel Frantisek Wiesner performed a tremondous total synthesis in $59$ steps of the 13-desoxydelphonine. In one of those steps there is a very tricky Wagner-Meervien rearrangement. I tried to ...
- 4,177
4
votes
2
answers
239
views
Why aren't there iron bones and eggs in nature?
As far as I know, most of the "hard things" in living creatures composed of calcium (for example, bones plated with calcium over the keratin structure, and eggshells and seashells with $\ce{CaCO3}$). ...
- 279
2
votes
1
answer
1k
views
High voltage AC water electrolysis not working
I was trying to use a $500~\mathrm V$ AC power supply to split water, but nothing happened. I tested everything with a $9~\mathrm V$ battery, and it all worked fine.
Why did it not work with the ...
- 49
27
votes
1
answer
7k
views
How can there be decimal subscripts in a molecular formula?
While learning about how batteries work I have encountered the following notation for a Li-ion cathode: $\ce{Li_{0.5}FePO4}$.[1]
According to Wikipedia, the subscript number in a reaction equation ...
- 944
3
votes
0
answers
770
views
Example of an endothermic reaction that can sustain itself for at least an hour?
Recall that in physical chemistry, the spontaneity of a reaction at constant pressure and a given temperature $T$ can be quantified by the Gibbs free energy
$$\Delta G = \Delta H - T \Delta S$$
A ...
- 698
1
vote
1
answer
861
views
Why does bromide not react with water when methyl ammonium bromide is dissolved in water?
In the following reaction, the salt $\ce{CH3NH3Br}$ is formed:
$$\ce{CH3NH2 + HBr -> CH3NH3Br} $$
In water this dissociates completely into $\ce{CH3NH3+}$ and $\ce{Br-}$
In my chemistry book, it ...
- 13
14
votes
2
answers
485
views
Serious introduction to the chemistry of explosives recommendation
I'm looking for a serious introduction to the chemistry (and perhaps to a lesser extend the physics) of explosives. Presupposition of basic university courses in Organic Chemistry and Thermodynamics ...
- 6,203
7
votes
1
answer
192
views
How did early chemists measure concentrations and purity?
My chemistry teacher loves going back through the history of famous chemists. This got me wondering how these chemists would first determine the concentration of a sample before they had any other ...
- 73
5
votes
1
answer
725
views
Help with finding intermediates in the synthesis of Ritalin
Here I have a Chemistry Olympiad question I'm doing that outlines the synthesis of Ritalin. So far I've worked out A, Anion B -, and compound C. You can see my workings, as I've attached them here too....
- 291
2
votes
1
answer
115
views
Volume Element in the Integral for Variational Method
I'm learning how to use variational method to calculate the energy of ground state helium. I understand how we can set up a trial wavefunction that is a product of two hydrogen-like wavefunctions; ...
- 551
-3
votes
1
answer
198
views
Would distilling a sodium fluoride solution generate hydrogen fluoride to any noticeable extent?
If you have a solution of NaF, and you boil it (to get pure water by distillation) can the fluoride ions in water separate from sodium ions and combine with hydrogen ions to form HF? ...
3
votes
1
answer
948
views
Acetophenone reacted with LDA and diethyl carbonate. Why do I need HCl?
I'm working on a practice problem that asks for the product of acetophenone and LDA reacted with diethyl carbonate. After this, it says step 2 is HCl. After I react the first step, I get the correct ...
- 65
0
votes
1
answer
493
views
Electrolysis of Anhydrous Sodium Hypochlorite
Considering liquid anhydrous sodium hypochlorite:
$$\ce{NaClO (l)}$$
Assuming the ions are free, What would be produced if this were electrolysed?
As I've found lots of information for it's ...
- 103
9
votes
6
answers
4k
views
How to correctly write "7 apples" according to the international system of units (SI)
According to international system of units (SI), we can write "7 kg of apples" to refer to the mass of these apples.
However, if we want refer to the amount of apples, that is, the number of ...
- 217
2
votes
1
answer
4k
views
formaldehyde strong odor neutralization
One of our customers used a very high dose of formaldehyde 37% solution (60 liter formaldehyde in 40 liter water) for disinfection in his chicken farm (saloon). Now he says the odor of formaldehyde ...
- 21
0
votes
1
answer
3k
views
When an expansion of a system does work on its surroundings, is the sign for work negative?
This question comes to me from trying to explain the answer $1.67\ \mathrm{L}$ of this question:
A cylinder with a moving piston expands from an initial volume of $0.250\ \mathrm{L}$ against an ...
- 253
18
votes
1
answer
3k
views
Fehling's test arrow pushing mechanism
I am currently attempting to generate an arrow pushing mechanism for the oxidation of glucose to gluconic acid using Fehling's solution. My original thought was to go the route of alcohol oxidation ...
- 189
2
votes
1
answer
2k
views
Why are weak acids not considered good leaving groups?
So today in my first year lecture my professor said that weak bases are good leaving groups. I understand why they are good leaving groups in comparison to unstable strong bases but why are weak acids ...
- 55
-3
votes
2
answers
782
views
What is the difference between Sodium Nitrate and NaNH3
I have almost no experience in chemistry so please excuse my ignorance. I am looking to purchase some Sodium Nitrate but the vendor I am dealing with has the chemical formula NaNH3 listed beside the ...
- 1
5
votes
1
answer
2k
views
Comparison of alkali and alkaline earth melting points - MO theory
If you compare the melting points of alkali and alkaline earth metals, you see that the latter have higher melting points. However, if you look at MO theory, then alkaline earth metals should have ...
- 73
1
vote
2
answers
927
views
How much sodium fluoride is needed to precipitate a calcium fluoride solution?
The question was:
If you are given a $\pu{1 L}$ solution of $\ce{CaF_2}$ where there is $\pu{2.0E5 M}$ $\ce{Ca^{2+}}$. How many milliliters of $\pu{0.1 M}$ $\ce{NaF}$ would you need to precipitate $\...
- 197
-2
votes
2
answers
1k
views
Why is bismuthine (BiH3, or bismuth trihydride) unstable if bismuth is considered to be the most stable heavy element?
Bismuth-209 is considered to be the most stable heavy element, though it is weakly radioactive.
Given that, why does bismuthine ($\ce{BiH3}$, or bismuth trihydride) have a half-life of only 20 ...
0
votes
1
answer
5k
views
Why isn't HCl called hydrogen monochloride? [duplicate]
Since HCl is a covalent compound, then it would be expected to be called hydrogen ***mono***chloride following the rules for naming. Instead it is named as if it were an ionic compound, without any ...
1
vote
0
answers
899
views
Equation or formula for calculating molecular orbital energies
Is there an equation, similar to the Rydberg formula, for calculating the energies of molecular orbitals?
For example, with the Rydberg formula, I can work out that the energy of a $1s$ orbital in ...
- 247
4
votes
2
answers
2k
views
"No variables in Z-matrix" error in scan calculation of Gaussian
I asked a similar question earlier this year but I'm still stuck with a similar problem.
Basically I'm trying to implement a scan calculation using both a z-matrix and Cartesian coordinates. I have ...
- 73
0
votes
1
answer
2k
views
Nickel plating with nickel acetate, nickel chloride, sulfur, saccharin and coumarin
I am a hobbyist trying to learn/apply a nickel electroplating process that I can safely do at my shop. My substrate is a machinable non-stainless steel with unknown carbon content, and I'm looking to ...
2
votes
1
answer
407
views
Spin quantum number of electron
Why is the spin quantum number of an electron +1\2 or -1\2 in an atom? Is this an experimental value or theoretical value?
- 21
4
votes
1
answer
142
views
Melting post-1982 minted U.S. pennies and aluminum: Why does the slag turn blue?
After melting aluminum inside of an iron crucible, I tossed in a handful of U.S. pennies that were minted post-1982. The slag began to burn a brilliant blue. What caused this?
1
vote
0
answers
862
views
Mixing two buffers of the same concentration, but of different pH
Does anyone know how to approach this?
I have two buffers of the same weak acid of the same molarity but at different pH
Let's say the pH of one was 8 and one was 7, how do I go about getting a pH ...
- 151
2
votes
1
answer
5k
views
Relationship between surface area and vapor pressure
How is vapor pressure independent of the surface area and volume of a liquid, although rate of evaporation depends on surface area?
Please someone help me I am totally confused.
user37097
1
vote
0
answers
206
views
Would combining essential oils and carrier oils be okay in terms of flash point?
With NO scientific, or chemical background, I am making my own beard oils. I found essential oil recipes online to mix with one or many carrier oils to make beard oil. I want to be original by going ...
2
votes
0
answers
505
views
What drives intercalation?
From Wikipedia:
intercalation is the reversible inclusion or insertion of a molecule
(or ion) into compounds with layered structures.
What is the "driving force" / mechanism that's responsible ...
- 4,257
9
votes
2
answers
2k
views
Le Châtelier's Principle and heat
Consider the following reaction at equilibrium.
$$\ce{A->B}, \Delta H < 0 $$
Suppose I increase the temperature. Now, quite a few people would invoke Le Châtelier's Principle and say that since ...
- 17.4k
0
votes
1
answer
4k
views
Why isn't CO2 flammable? [closed]
Given that $\ce{CO2}$ is comprised of carbon and oxygen, why
isn't it a flammable gas?
- 279
1
vote
1
answer
567
views
How would one make a non-toxic pen out of osmium?
Osmium is the densest element in the periodic table. However, it is toxic in its pure form. Is there a way to create a standard pen out of osmium but coat it in a dense material that isn't toxic to ...
- 113
9
votes
3
answers
1k
views
NMR calculations with NWChem quantum chemistry program
I tried experimenting with some ab initio NMR calculations using the NWChem program. I used quinuclidine as a simple test case. The input file was:
...
- 2,794