# All Questions

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### 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 ...
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 ...
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 ...
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 ...
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
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 ...
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 ...
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
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 ...
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/...
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) ...
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 ...
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
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 ...
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 ...
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
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 ...
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
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 ...
164 views

1 vote
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: ...
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
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 ...
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 ...
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 ...
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 ...
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
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 ...
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 ...
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 ...
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 ...
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....
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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. ...
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 ...
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 ...
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?)...
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 ...
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, ...
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 ...