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30 views

Energy values of steam reformation, water gas shift, hydrogene and methane burning seem to not add up correctly

I found the following reactions including the Energy-Delta all in Wikipedia and in at least one more source each: (Delta with "-" are exothermic reaction which is generating heat) Steam ...
3 votes
2 answers
5k views

Carbonyl bond vs alkene bond

Why is that carbonyl bonds are stronger than those of alkenes? It's a basic question but I've never really thought much about it. I've read several times that carbonyl bonds are shorter and you need ...
0 votes
1 answer
18 views

How are substances identified in the real world? [closed]

Recently in AP Chem I did a lab that involved doing various tests (melting on hot plate, flame test, etc.) to identify a metal out of a list of metals. This had me wondering: how do chemists identify ...
3 votes
1 answer
79 views
+50

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 ...
0 votes
1 answer
37 views

How do you calculate the pH of 0.01 M H2S solution (hydrogen sulfide, an amphiprotic acid)?

I found a question in a physical chemistry book What is the pH of $\pu{0.01 M}$ $\ce{H2S}$ solution? Given, $K_\mathrm {a_1} = 9×10^{-8}$ and $K_\mathrm{a_2} = 1.2×10^{-13}$. I thought of applying ...
1 vote
0 answers
5 views

The difference between Zn and Al on acid and base reaction

Because it was written on my textbook that Zn and Al dissolves in acid and alkali, I tried. When I put Al in NaOH solution it reacted immediately. But when I put Zn in the same concentration of NaOH ...
0 votes
1 answer
55 views

Where does the residue accumulate in the boiling point composition curve?

My teacher was teaching the boiling point composition curve for fractional distillation and provided the diagram shown below. It shows that the residue starts accumulating at the point on the vaprous ...
2 votes
1 answer
7 views

Contaminants in Ion Exchange Chromatography significance?

I am a high school senior and decided to do a project on the essential amino acid composition of varying vegan protein mixtures. I have run into a problem concerning protein purification. One of the ...
1 vote
1 answer
37 views

Can two wavefunctions of 1s electrons in He atom have opposite phase?

Suppose we have a He atom, I understand that it's wavefunction can be written as product of 2 hydrogenic orbitals, $$Ψ(r_1,r_2) = ψ(r_1)ψ(r_2)$$ Which in this case, are two 1s wavefunctions with ...
4 votes
0 answers
54 views

Python implementation of the Lilly Medchem Rules code?

As the title suggests, I am looking for a Python implementation of the Lilly filter from the paper: https://pubs.acs.org/doi/full/10.1021/jm301008n. The shared code on GitHub (https://github.com/...
11 votes
3 answers
2k views

How can steel be so different from iron, even if amount of carbon is small?

Perhaps I am too naive, but I am having a hard time visualizing how even 'high-carbon' iron and steel alloys are maybe, at most, about four percent carbon by mass, which still means only one (smaller) ...
-2 votes
0 answers
21 views

Is there any material that, subjected to electricity, extends in size in multiples without substantial change in heat for human use?

Is there any material that can molecularly restructure so as to expand its intra- or inter-molecular distance by no less than three-fold without substantially losing its structural integrity and ...
-1 votes
0 answers
9 views

How do you count a Tp ligand's electrons using the covalent method?

I'm confused because say, you have (Tp)Ni(CH3)2 you'll have a 17 electron species in an oxidation state of +3. I thought the electron counting would be like this: Ni(0) = +10 electrons charge = +0 ...
1 vote
1 answer
62 views

How are photons converted into thermal energy?

I know when light strikes an object it excites electrons into higher energy states. I know thermal energy is basically just a lot of atomic and molecular kinetic energy. Does the excitation of the ...
2 votes
1 answer
36 views

Covalent character of bonds in uranium hexafluoride

In one of the questions in a qualifying exam it said that $\ce{UF6}$ is a "covalent compound". This fits the physical properties of the compound well, e.g. low boiling point, existence as ...
35 votes
3 answers
41k views

Why do atoms generally become smaller as one moves left to right across a period?

It seems to me that the addition of electrons and protons as you move across a period would cause an atom to become larger. However, I'm told it gets smaller. Why is this?
1 vote
1 answer
99 views
+50

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 ...
2 votes
2 answers
898 views

Electrolysis using electrodes of metals whose ions are in solution

When we perform electrolysis of say an aqueous solution of silver nitrate with silver electrodes, silver ions, having a greater reduction potential than water, accept electrons and are deposited at ...
1 vote
1 answer
41 views

Colour of ferrous hydroxide crystal

My chemistry teacher said that pure $\ce{Fe(OH)2}$ is a "white" crystalline solid in anaerobic environments, and acquires the usual green tinge, the colour of $\ce{Fe(II)}$, when in contact ...
3 votes
4 answers
164 views

Will the total equilibrium pressure increase in gas phase reaction PCl5(g) ⇌ PCl3(g) + Cl2(g) after chlorine is removed?

Will the total pressure be greater than the initial equilibrium pressure if all $\ce{Cl2}$ is removed and the following reaction is allowed to re-equilibrate? $$\ce{PCl5(g) <=> PCl3(g) + Cl2(g)}$...
1 vote
0 answers
95 views

Practical considerations for electrolysis of water

I'm interested in electrolysis of water to form $\ce{O2}$ and $\ce{H2}$, as pure as possible given the constraints of a "household chemical" setup. I've read other questions on here (in ...
0 votes
2 answers
28 views

Can metals have both Fracture Toughness and Elasticity properties?

Fracture Toughness is the resistance of a material to cracking and Elasticity is the ability to bend without breaking. I want to know if there is any metal or metal alloy that can easily bend without ...
1 vote
1 answer
250 views

Can hydrogen peroxide dissolve rust?

wd-40's "help page" on "How To Loosen Rusty Bolts, Screws And Nuts" states: Hydrogen peroxide can dissolve rust. Applying hydrogen peroxide to the fasteners and letting it sit is ...
-1 votes
1 answer
40 views

Are electrodes in an electrolysis unique for every electrolyte or can any random electrode be used with an electrolyte during electrolysis

For example, during the electrolysis of water, platinum electrodes are used, why can't I use any other electrode as long as they are conductors? why does some electrolysis require specific electrodes ...
2 votes
2 answers
86 views

Why doesn't hydrochloric acid oxidize tin to tin(IV) chloride?

Diluted hydrochloric acid oxidizes tin to $\ce{Sn^2+}$ ion: $$\ce{Sn + HCl(aq) -> SnCl2(aq) + H2(g)}$$ Why is oxidation not complete? $\ce{Sn^4+}$ has closed shell and is more stable.
1 vote
0 answers
25 views

How does alkaline pipe cleaner corrode plumbing?

The siphon of my bathroom sink was clogged up again, and I became curious on why it clogged up so quickly each time. So I decided to open the pipe and was shocked to see the plumbing like this: ...
-1 votes
0 answers
16 views

Predicting acid-base equilibria

I was looking at acid-base equilibria of weak acids and weak bases. To determine the equilibrium constant of a reaction of those, I found a formula on the libretexts page: Where ΔpKa is the ...
1 vote
1 answer
269 views

Obtaining atomic form factor from electron density?

I know that atomic form factors for x-ray scattering are obtained by Fourier transform of the electronic charge density. I am looking for a citable elementary source (book, review, article) which ...
2 votes
1 answer
109 views

Hydrochloric acid substitute in an Iron-gall ink solution

Recently I started experimenting with making my own ink to be used in fountain pens. I was wondering if hydrochloric acid in an iron-gall ink is used to prevent sediment ONLY by lowering the pH of ...
0 votes
1 answer
44 views

Is it possible for an appropriately vaporized crystal to have vapor properties in any way related to it's crystal?

Is it possible for an appropriately vaporized$^{1}$ crystal to have vapor properties in any way$^{2}$ related to it's crystal, or unique to the fact it was a crystal in it's previous phase? $^{1}$ As ...
-1 votes
0 answers
18 views

Why ATP hydrolysis is a exergonic reactions? [duplicate]

Bond formation releases energy, i.e. They are exergonic reactions and on contrary breaking of bonds require an input energy (endergonic reactions). Then why the hydrolysis of ATP i.e. Breaking of ...
-4 votes
0 answers
26 views

Hydrogen peroxide molecules are monoatomic and forms (((OH)2)2- [closed]

How can this be true ? It should be tetraatomic or am I missing something else
-2 votes
0 answers
13 views

Naming/Formulae of Covalent Compounds [closed]

I know how to name covalent compounds by looking at the formula and how to write the formula by looking at the name, but what if neither are given? I thought it was the same as ionic compounds: it ...
-3 votes
0 answers
38 views

Reduction of carboxylic acid with red phosporous/HI [closed]

According to the class 11 theory it is mentioned that red P/HI will reduce Carboxylic groups to alkanes at 200 degree.But I cannot find any article for it.Now I am doubted whether red P/HI reduce ...
0 votes
2 answers
56 views

Does ozone decay in pure water?

I am trying to understand ozone decay in water and its rate. Some say ozone has a first-order decay at high pH and second-order kinetics at low pH. Does ozone decay in pure water? Or does it decay ...
0 votes
0 answers
20 views

How do the intermolecular forces of attraction between two molecules of a gas vary with the type of gas taken?

I already know how the van der Waals forces vary as a function of intermolecular separation, but how do they vary with the gas taken? For example, do these forces of attraction fall off at exactly the ...
5 votes
0 answers
68 views
+100

How exactly thermal infrared (e.g. FLIR) cameras image methane leaks? Are they measuring a temperature difference or an emissivity difference or...?

The story Infrared camera shows the impact of vehicle emissions says: In an effort to visually demonstrate the potentially fatal impacts of air pollution, FLIR Systems (Wilsonville, OR, USA; www.flir....
-2 votes
0 answers
41 views

Question on reaction of Tin with strong base

I learned that tin reacts with HCl like below.$\ce { Sn +2HCl -> SnCl2 + H2}$But I also learned in my textbook that tin reacts with strong base when heated like this.$\ce{Sn + 2NaOH + 4H2O->Na2[...
2 votes
4 answers
15k views

Why do simple molecular substances have weak intermolecular forces and why do giant covalent substances have strong intermolecular forces?

Why do simple molecular substances have weak intermolecular forces and why do giant covalent substances have strong intermolecular forces? I understand that in simple molecular substances the atoms ...
-1 votes
0 answers
33 views

Misconceptions about resonance?

I stumbled upon resonance as a topic, and have been studying about it te past few weeks, and I developed some understanding of a few key facts, which I wanted to post a few doubts here as many are ...
0 votes
0 answers
27 views

Can vinegar be used to clean wood (a porous surface) after it has been cleaned with germicidal bleach?

I recently cleaned moldy air vents and hardwood floor with diluted germicidal bleach water (1/3 cup bleach to 1 gall). I would like to go back in with vinegar to make sure the mold stays gone, mostly ...
0 votes
1 answer
109 views
+50

Why is Hg2Cl2 less soluble in water than HgCl2?

I learned that $\ce{Hg2Cl2}$ is almost insoluble to hot water and $\ce{NH3}$ water in my textbook, but $\ce{HgCl2}$ dissolves well in water. I wanted to know the reason and searched for it. It's ...
0 votes
1 answer
59 views

Getting magnesium chloride gunk off a wood shelf

I have a situation. Some magnesium bath salts got left on a wood shelf in my bathroom in a bag that was not closed. Being hydroscopic, it sucked up a ton of water, and then spilled onto the wood. ...
2 votes
1 answer
173 views

On the exact definitions of Frenkel and Schottky defects

The wiki page on vacancy defects says; It is also known as a Schottky defect, although in ionic crystals the concepts are not identical. As far as I'm aware, they're the same. Furthermore, the wiki ...
-4 votes
0 answers
13 views

Why is the given process not isobaric despite pressure being constant, and why can’t we use the formula for entropy of isothermal process as shown [closed]

enter image description here Why is this not an isobaric process, despite Pressure being constant? And also why can’t we use the formula given in T-11 for isothermal process?(T-11 refers to the third ...
-1 votes
1 answer
40 views

Why an irreversible isobaric process won’t satisfy the above given equation in the image above

Here, my doubt is , why is option D incorrect?( the ans key says A,B,C )... in isobaric process, the work done is same for both reversible and irreversible processes, then why isnt D correct as well?)...
2 votes
1 answer
199 views

Azulene Conjugation?

I'm trying to figure out how azulene is an aromatic compound; I understand it is cyclic, flat, and follows Huckel's rule, but I don't understand how it is conjugated. I have circled what I believe to ...
-2 votes
0 answers
40 views

Why did my ester synthesis with sulfuric acid turn black? [closed]

For my study we had to synthesize a ester. I was using hexanoic acid with 1-propanol and sulfuric acid as a catalyst in a dean-stark set up. Around an hour into the synthesis the mixture turned black, ...
0 votes
1 answer
27 views

Why the density of liquid decreases and density of vapour increases as we approach towards the critical state/point

Pressure and temperature have opposite effects on density. As temperature increases at constant pressure density decreases and as pressure increases at constant temperature the density increases (and ...
5 votes
1 answer
1k views

The boiling points of Alkali metal group

As I know, the melting points of Alkali metals decrease down to the group due to decreasing of the energy of the metallic bond. But according to my understanding, after it has become to liquid the ...

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