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Questions tagged [hydrogen]

Questions regarding the chemical properties of hydrogen and its behavior in reactions and compounds.

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59 views

Hydrogen visible transitions

When dealing with electrons and the electromagnetic spectrum, why are there only four visible transitions in the hydrogen atom?
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5k views

Why are isotopes of hydrogen the only ones with special names?

Why does no other element but hydrogen get special names for its isotopes?
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199 views

Hydrogen bonding

It is mentioned in my textbook: "Hydrogen atoms of water molecule create strong electrical field due to their small sizes" How is the size related to electrical field and its strength? A little ...
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375 views

What typically happens to H2 molecules released into atmosphere (with no spark source)?

I'm wondering what happens when $\ce{H2}$ leaks from say a transmission pipe in an unenclosed area. No immediate source of ignition, I know it rises more quickly than helium (x2 I believe) and ...
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351 views

Reliable automatic addition of hydrogens and charge assignment to small molecules at given pH?

I have some PDB structures of small molecules with missing hydrogens. Is there a software available that places missing hydrogens and assigns a charge to the molecule that is reliable? I am looking ...
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Why are hydrogen ions always associated with another molecule?

I was reading N.C.E.R.T. class XI part 2 book and chapter Hydrogen,when I came across this statement: Loss of the electron from hydrogen atom results in nucleus ($\ce{H+}$) of ~1.510–3 pm size. ...
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Comparing heat of hydrogenation per mole of butenes and 1,3-butadiene

The question asks us to select the compound with the smallest heat of hydrogenation per mole out of the following: a) 1-butene b) trans-2-butene c) cis-2-butene d) 1,3-butadiene Since all four ...
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3answers
838 views

How to add hydrogens to a crystal structure?

PDB protein crystal structures most of the time lack hydrogen atoms. Usually I use PyMOL (h_add) but it does not always seem to be giving the correct result. What ...
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2k views

What is the bonding type in hydrides of group 2 elements?

In one of my MCQ questions, there was a statement saying all group 2 elements form covalent hydroxides. I know it is incorrect. I know that $\ce{BeH2}$ is a covalent hydride. What about the rest? Are ...
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1answer
188 views

Is there an electrolyte that will halt the production of Hydrogen in water electrolysis?

Care must be taken in choosing an electrolyte, since an anion from the electrolyte is in competition with the hydroxide ions to give up an electron. An electrolyte anion with less standard electrode ...
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172 views

What fraction of hydrogen in air results in an explosive mixture?

I would like to know if there is documented evidence of the quantity of hydrogen to air that must be present in the mixture to risk explosion or flame.
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1k views

Really how rare are hydrogen atoms?

Hasok Chang, a chemist, but perhaps more a philosopher recently published the book Is Water H2O? . Chang used the question and an extensive web of arguments ultimately as a platform to support a ...
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1answer
2k views

Equivalent hydrogens in 2,3-dimethylbutane

So while calculating for the relative yield of monochlorination for 2,3-dimethylbutane, I was counting the primary hydrogens, I counted 6, but in fact it was 12. Why is it 12? How do you find ...
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417 views

Hydrogen Fuel Cell and Battery

For hydrogen fuel cell to produce electricity, hydrogen will need to be supplied to the anode. To split oxygen and hydrogen from water and obtain hydrogen, we need to use electrolysis. To use ...
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1k views

Does hydrogen react with air at room temperature and pressure?

I have a container with 3% hydrogen and the rest is air. How fast will the hydrogen get oxidized by air? How much will the reaction speed up with increased temperature?
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1answer
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Why are so many wave functions associated with hydrogen?

According to Wikipedia, there's an infinite set of possible wavefunctions (orbitals) for the hydrogen atom: $$\psi_{n\ell m}(r,\theta,\phi) = \sqrt {{\left ( \frac{2}{n a_0} \right )}^3\frac{(n-\ell-...
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154 views

Are the energies of orbitals that are not filled in an atom, equal?

In a hydrogen atom only 1s orbital is filled. Does this mean that the energies of all other orbitals are equal? If so,why?
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571 views

Calculating moles of Hydrogen gas in multiple gas container

If there was a 500 mL container filled with oxygen and hydrogen so it burns completely (2H:1O), how many moles of hydrogen gas would there be if there if pressure is 101.3 kPa and the temperature is ...
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2k views

On the stability of deuterium

The isotope of hydrogen, tritium, is indeed radioactive resulting in $\ce{^3He}$ through beta decay. But what of the radioactively 'stable' isotope deuterium? Are all deuterium atoms destined to be ...
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Which orbitals of the hydrogen atom are degenerate for n=3?

Which of the following orbitals are degenerate in the hydrogen atom with $n = 3$? A. II and III only; B. I and IV only; C. I, II, and IV only; D. II, III, and IV only; E. all. The ...
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469 views

Structure of Metallic Hydrogen

I am simply curious what the theoretical arrangement of metallic hydrogen would be. I found this article which gives a picture, but I don't understand what the labels mean (e.g. is H5 an isotope, ...
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1answer
84 views

Hydrogen can be stored? [closed]

Please tell about the hydrogen gas storage and the pressure created in tank. what is the calorific value of hydrogen gas when it is burnt?
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1answer
6k views

Relationship between surface area of electrode and reaction rate of hydrogen in fuel cells

I am looking at the effects of increasing the surface area of which the flowing hydrogen fuel is in contact with the anode in a fuel cell. At the anode the hydrogen is catalytically split into ...
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2answers
11k views

alpha-hydrogen atom and keto-enol tautomerism

The following is an extract from my book- For an aldehyde or a ketone to exhibit keto-enol tautomerism, it is essential that it must have atleast one $\alpha$-hydrogen atom. Thus, acetophenone, ...
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10k views

Ethane and ethene: which is easier to burn? Which one burns hotter? Why?

Anything that burns "easy", has a low activation energy ($E_\mathrm a$) for the burning process. Anything that burns hotter, will have a lesser enthalpy and thus, will have a more aggressive ...
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2k views

Why is the electronegativity of hydrogen 2.20?

Well, I was doing research about the ways we can measure electronegativity and I just realized there must be an arbitrary electronegativity set for an specific element to give us the relative amounts ...
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How is bonding in the trihydrogen cation and triatomic hydrogen possible?

According to wikipedia $\ce{H^+3}$ and $\ce{H3}$ are possible and have been synthesized. It says that $\ce{H^+3}$ is stable too. Can anyone please tell me how is the bonding possible? Hydrogen has a ...
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904 views

Preventing the gas when Hydrogen peroxide is added to a detergent

In organic detergents, when I add Hydrogen peroxide to increase the stain removing feature a gas is produced. How should I prevent the gas production process?
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Why is the ionization energy for Hydrogen non-zero?

There are no other electrons to collide, repel and kick Hydrogen's single electron to a distant nucleus. And that a single electron is tightly attracted to the nucleus by the electrostatic energy ...
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6answers
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Why do we use helium in balloons?

While I was looking at the periodic table today, I realised that there were gases that were much lighter than helium such as hydrogen. If hydrogen is lighter than helium, why do we insist on using ...
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50k views

Why is formic acid a stronger acid than acetic acid?

I am told that because the methyl group is electron donating in the conjugate base of acetic acid, this destabilizes the conjugate base by exacerbating the existing negative formal charge on the ...
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1answer
441 views

Reduce chlorine gas

I have a simple electrolysis setup which uses aqueous sodium chloride as electrolyte. The problem is that, the setup makes tons of chlorine gas along with hydrogen (I only want hydrogen). I didn't ...
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2answers
28k views

Hydrogenation stereochemistry-Pd,Pt, Ni catalysts

When my textbook talks about hydrogenation using Pt, Pd or Ni heterogeneous catalysts, it never mentions if it is anti or syn addition. It simply jumps on to say that for alkynes, NiB2 (P-2) catalysts ...
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1answer
1k views

What are possible side reactions for the generation of hydrogen via electrolysis?

I recently completed making a simple water electrolysis setup to generate hydrogen which uses two graphite rods from a standard AA battery. The power source is a $24~\mathrm{V}$ $6~\mathrm{A}$ adapter....
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853 views

Normal and heavy water mixing

This question seems silly, but this just came in my mind while i was learning about hydrogen. Means will there be any reaction when $\ce{H2O}$ will be mixed with $\ce{D2O}$?
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181 views

How much water would one loose if one burns hydrogen and oxygen?

By using electrolysis one can separate hydrogen and oxygen, but when burning hydrogen and oxygen together steam is released, therefore creating water. My question is: how much of the original ...
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3answers
423 views

Hydrogen as a fuel really worth it?

Is hydrogen good to be used in cars? How much of traveling can a car do with medium sized balloon filled with hydrogen? Is it worth it?
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3k views

Reaction mechanism of combustion of hydrogen

After a discussion about the usefulness of hydrogen fuel for cars with a friend of mine, I wondered what the reaction mechanism for combustion of $\ce{H2}$ was. I only study (well almost) organic ...
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1answer
928 views

Can electrolyzing ice cause an explosion?

I know electrolyzing water separates it into hydrogen and oxygen. However, I am curious, if ice is electrolyzed, could it explode? My thought process is that oxygen and hydrogen bubbles would build ...
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1answer
94 views

Hydrogen atom energy level [closed]

The energy level of a hydrogen atom in its ground state is $-13.6\ \mathrm{eV}$. How is this value calculated and how can we calculate the same for different orbits?
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86 views

What's the Acid Ionization Constant of the Hydrogen Proton?

What is the $\ce{K_{a}}$ value for $\ce{H^+}$. I understand that the hydrogen proton doesn't stick around in solution by itself for very long. Nonetheless, does it have a $\ce{K_{a}}$ value? Can it ...
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1answer
298 views

Potential term in the hydrogen atom Hamiltonian

Here is how I saw the Hamiltonian being written in one Quantum Mechanics book: $$\hat{H} = -\frac{\hbar^2}{2m_\mathrm{e}r^2} \left[\frac{\partial}{\partial r}\left(r^2\frac{\partial}{\partial r}\...
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Identifying protons in NMR using the J values

When looking over an old organic midterm I came across this question. As you can see I got half of it right, but honestly I'm not sure how I got that one right or how you would answer this in ...
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1answer
2k views

How can the 18 electron rule be used to explain that Fe(η5-C5H5)2 doesn't react with hydrogen but Ni(η5-C5H5)2 does?

Fe(η5-C5H5)2 does not react with hydrogen, but its nickel analogue, Ni(η5-C5H5)2 is readily hydrogenated to give Ni(η5-C5H5)(η3-C5H7). Use the 18 electron rule to explain this behaviour. My answer so ...
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Are all (pure) alkanes, alkenes and alkynes - tasteless, odourless and colourless? [closed]

non-pure alkanes have a taste, but Are all pure hydrocarbons, tasteless, colourless and odorless? Are there hydrocarbons that do have a taste, colour, odor? If so, what makes these pure hydrocarbons ...
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1answer
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How does malachite react with acid?

I performed an experiment where I did this: Add one spatula of malachite to a test tube, add dilute hydrochloric acid to the malachite until the test tube is one third full. Note observations and ...
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Rate and mechanism of the reaction of Mg and HCl

In the reaction between hydrochloric acid and Magnesium the overall reaction is: $$\ce{Mg + 2HCl -> MgCl2 + H2}$$ My proposed mechanism of reaction is that $\ce{HCl}$ dissociates in $\ce{H2O}$ ...
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118 views

Could this be a feasible fuel system?

First off, please forgive me, I am a chemistry novice! Overall Process Fuel for the system is distilled water Split water into Hydrogen and Oxygen (electrolysis or similar process) Exhaust Oxygen ...
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4answers
26k views

How explosive is hydrogen gas?

I want to electrolyze water to get oxygen and hydrogen. I want to mix them in a regular balloon and ignite it. How much hydrogen would you need in a 2:1 ratio with air for it to be dangerous? Is this ...
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Lifetime of a (reversible) hydrogen fuel cell system

I am trying to determine how long a system that constantly converts water into H and O and then back will last, as in roughly how many cycles. Now this system can either be made of say a reversible ...