Chemistry Stack Exchange Community Digest

Top new questions this week:

Is there any aromatic system which doesn't contain any ring?

I'm curious if there are any aromatic systems that don't contain any rings. I just wonder and want to know if there is any exception to the aromatic system. I know the definition of aromaticity is ...

organic-chemistry aromaticity  
user avatar asked by Sơn Nguyễn Score of 5
user avatar answered by Oscar Lanzi Score of 6

Is it appropriate to call an element an amphoteric substance?

In most of Japanese high-school textbook it is written that Al,Zn,Sn and Pb are amphoteric element(in Japanese 両性元素)because they react both with strong acid and base. For example Al reacts like below. ...

acid-base oxides definitions  
user avatar asked by satoru kurita Score of 5
user avatar answered by AChem Score of 4

Intense purple colour of litmus paper in contact with calcium oxide

When conducting an experiment to identify some common chemicals, I tested crystal/powder samples of the chemicals with moist litmus paper. When I put a piece of blue paper on some $\ce{CaO}$ powder, ...

acid-base color  
user avatar asked by jhphysics Score of 4
user avatar answered by Oscar Lanzi Score of 5

Equilibrium Bond Length & Diatomic Molecules

Must every diatomic molecule always have an equilibrium bond length? That is, is there always a distance between two nuclei such that the Coulomb attraction between the electron and protons ...

physical-chemistry bond molecules electrostatic-energy  
user avatar asked by Vera Leighton Score of 4
user avatar answered by Karsten Score of 5

Suitable solvents to dissolve Aluminum Chloride (anhydrous) without generating Hydrochloric Acid (aqueous or gas)

Hypothetically, I have a chemical tank that was brought out of service and the solid deposits at the bottom of the tank primarily contain aluminum chloride. The whole system never sees water, and the ...

inorganic-chemistry solubility solvents vapor-pressure chemical-engineering  
user avatar asked by Sam Score of 4
user avatar answered by Oscar Lanzi Score of 4

Does carbon dioxide come out of solution on freezing?

Years ago in a lab where I was working someone had the excellent idea of cooling down their can of coke by pouring liquid nitrogen over it. The can exploded and resulted in quite a mess. My question ...

physical-chemistry water gas-laws  
user avatar asked by Dirk Bruere Score of 2
user avatar answered by Oscar Lanzi Score of 3

Polymer purification by reprecipitation troubleshooting

I am synthesizing new polymer that has not been reported before. The structure of the polymer is based on indacenodithienothiophene unit and thiophene. I used Stille polymerization. As monomers, I ...

aromatic-compounds polymers organometallic-compounds purification  
user avatar asked by Krang Lee Score of 2

Greatest hits from previous weeks:

What is the pKa Range for weak acids and bases?

Am I correct in assuming that the following is true? $\mathrm pK_\mathrm a < 3$ is for a strong acid $3 < \mathrm pK_\mathrm a < 7$ is for a weak acid $7 < \mathrm pK_\mathrm a < 11$ ...

physical-chemistry acid-base ph  
user avatar asked by user2679447 Score of 6
user avatar answered by ShuklaSannidhya Score of 12

Positive or Negative Anode/Cathode in Electrolytic/Galvanic Cell

In a galvanic (voltaic) cell, the anode is considered negative and the cathode is considered positive. This seems reasonable as the anode is the source of electrons and cathode is where the electrons ...

physical-chemistry electrochemistry  
user avatar asked by 1110101001 Score of 58
user avatar answered by Philipp Score of 45

What is the reaction between oxalic acid and potassium permanganate?

I've already searched online some information about this equation, but everywhere I read, there's also sulfuric acid, which we did not use in the laboratory. We only used potassium permanganate and ...

inorganic-chemistry experimental-chemistry redox  
user avatar asked by ChairOTP Score of 6
user avatar answered by kaliaden Score of 10

What is the carbon dioxide content of a soda can or bottle?

I sort of know how carbonated beverages are carbonated: a lot of $\ce{CO2}$ gets pushed into the liquid, and the container is sealed. There are at least two things I don't know. First, how much carbon ...

solubility gas-laws mixtures  
user avatar asked by Colin McFaul Score of 12
user avatar answered by mannaia Score of 4

Effect of impurities on melting point

This is a 10th-grade question. The melting point of a substance decreases with increase in presence of impurities in it. The melting point of ice decreases from 0 °C to -22 °C on mixing salt in it ...

physical-chemistry melting-point  
user avatar asked by Prateek Raghav Score of 5
user avatar answered by Li Zhi Score of 6

Reaction of silver nitrate and hydrochloric acid

Consider the reaction of $\ce{AgNO3}$ and $\ce{HCl}$. I read that silver chloride would be formed. But $\ce{H} > \ce{Ag}$ in reactivity, then how could $\ce{Ag}$ displace $\ce{H}$ from $\ce{HCl}$ ? ...

inorganic-chemistry precipitation  
user avatar asked by RandomStudent Score of 8
user avatar answered by thomij Score of 14

Reason for the stronger acidic property of phenol than alcohol

In phenol, pulling the $\mathrm{p}_z$ electrons from the oxygen atom into the ring causes the hydrogen atom to be more partially positive than it is in aliphatic alcohols. This means it is much more ...

organic-chemistry acid-base aromatic-compounds orbitals phenols  
user avatar asked by Eliza Score of 23

Can you answer these questions?

Where do lactone groups occur in graphene oxides and how are they identified using FTIR measurements?

Usually, the literature (for example, Serodre et al. [1]) shows the occurrence of lactones in graphene oxides through potentiometric titration measurements. In the nanosheets, do these groups occur in ...

titration carbon-allotropes  
user avatar asked by Nathan Vinicius Score of 1

Why Hg doesn’t form hydroxide?

In my textbook it was written that if you put alkali solution into Hg2+ solution you won't get Hg(OH)2 but you get HgO. And this is because Hg has high electronegativity and this makes polarization of ...

electronegativity hydrolysis mercury  
user avatar asked by satoru kurita Score of 1

Why aluminum does not form ammonia complex ion?

I learned in my textbook that zinc forms more stable complex ion with NH3 than OH- because NH3 has only one lone pair and that makes repulsion between d orbital electron in zinc and lone pair electron ...

bond solutions electrons ligand-field-theory  
user avatar asked by satoru kurita Score of 2
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