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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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14
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3answers
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 ...
19
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1answer
3k views

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. ...
8
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1answer
2k views

Does the hydrogen ion actually exist? [duplicate]

A chemistry test I did was an IGCSE test. One of the questions was Is Hydrogen Chloride ionic or covalent? Now, on a sheet I have been given, it states the hydrogen ion is $\ce{H+}$. So, it forms ...
14
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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 ...
5
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2answers
11k views

Why is platinum used as a catalyst in fuel cell electrodes (and elsewhere)?

I have rather basic knowledge of chemistry (at the level of a first year college class). But maybe somebody can still clarify with some simple words: What makes platinum a good catalyst for the ...
4
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1answer
3k views

Stability of ortho- and para-hydrogen

can the stability of ortho-hydrogen greater than para-hydrogen can be stated as this? The intrinsic energy of ortho is greater than para-hydrogen and also with rise in temperature %of ortho form ...
4
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2answers
6k views

When a molecule loses hydrogen atoms, does it become oxidised?

I had the following question on a bio test covering cell respiration and glycolysis, but I'm not sure if I agree with the answer. When a molecule loses hydrogen atoms (as opposed to hydrogen ions),...
8
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1answer
1k views

Why do spin isomers of hydrogen (ortho and para hydrogen) change their nuclear spin with temperature variance?

My book says that ordinary dihydrogen contains 75% ortho and 25% para forms of hydrogen, while at significantly lower temperatures (like 20K) ortho and para hydrogens are 0.18% and 99.82% respectively....
5
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2answers
8k views

Why doesn't hydrogen displace metals from their oxides?

As I understand it, a displacement reaction is where a more reactive element kicks out a less reactive element from a compound. For example, chlorine is more reactive than iodine, so chlorine will ...
31
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1answer
10k views

Why are there two Hydrogen atoms on some periodic tables?

Most periodic tables only feature one Hydrogen atom, on the top of the first group. But some, like the one I was given, also show Hydrogen in the 7th group, to left of Helium. Why are there two ...
8
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1answer
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 ...
5
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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 ...
5
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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?
5
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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 ...
4
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2answers
409 views

Can gaseous hydrogen and gaseous oxygen be compressed without reaction?

I'm looking into building a clean Bunsen-style burner (or rocket engine - I haven't decided yet). I will be using electrolysis to extract hydrogen and oxygen from water, but the apparatus I am ...
3
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1answer
356 views

Alkalide compounds

I have read much more about metallic hydrides but I am totally confused about "inverse alkali hydrides" or "hydrogen alkalides" while reading refer to this. What are these compounds and how do they ...
2
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1answer
1k views

How can difference in neutron number cause a difference in ionisation enthalpies?

It’s a well known fact that protium,deuterium and tritium have the same number of electrons and protons but different number of neutrons. It is expected that their ionisation enthalpies should be same ...
30
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3answers
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?
29
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1answer
538 views

How does Palladium dissociate H₂ so easily?

If I understand correctly, $\ce{H2}$ in the presence of $\ce{Pd}$ readily dissociates as it dissolves into the metal. With the dissociation energy for the $\ce{H—H}$ bond being so large, how is this ...
26
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3answers
23k views

Why can't Pd/C and H2 reduce both the alkene and carbonyl portions of α,β-unsaturated carbonyls?

Why is it that the major product of the reduction of chalcones the ketone and not the monoalcohol? In other words, Why isn't the major product a benzyl alcohol? From what I understand, catalytic ...
21
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5answers
15k views

Is there such a thing as an acid without a hydrogen?

I'm in AP Chemistry and we are learning about the Brønsted-Lowry model and my teacher mentioned that "for the most part" acids have hydrogen, could there be such a thing as an acid that has no ...
17
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4answers
94k views

Why are there multiple lines in the hydrogen line spectrum?

Hydrogen has only one electron, yet it exhibits multiple lines in a spectral series, why is this?
8
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2answers
7k views

Why is there a need of polar coordinates to solve the Schrödinger wave equation for the hydrogen atom?

Why is there a need of polar coordinate to solve the Schrödinger wave equation for the hydrogen atom? I went through some standard text books but I am feeling rather confused about the explanation.
8
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3answers
837 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 ...
13
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1answer
11k views

If electrolysis splits water, why does only either hydrogen or oxygen (but not both) bubble up on one pole?

If electrolysis splits water, then that means that $\ce{H2O}$ is split into $\ce{H}$ and $\ce{OH}$ or $\ce{O}$. How come that if a water molecule is split at e.g. the negative pole (anode), only the ...
12
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3answers
4k views

Difference between Lindlar and Rosenmund catalysts

Is there any difference between the Lindlar and Rosenmund catalysts? I've checked around, and it seems the same compounds are used to make both. Is there a difference in their reactivities or are they ...
3
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1answer
2k views

Why is the entropy of deuterium greater than that of hydrogen gas

Why is the entropy of deuterium more than that of hydrogen gas? I thought about it but couldn't figure out a reason for why that would happen. Why would the number of neutrons in the nucleus ...
0
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1answer
4k views

Can reaction of gastric acid with swallowed things be dangerously exothermic?

Okay, okay. I know that swallowing a large enough amount of any substance would be considered dangerous. That isn't the point of this question, however. As you probably know, the stomach has ...
7
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2answers
5k views

Why are hydrogenation reactions exothermic?

I learned that all reactions that yield hydrogen are endothermic (such has reforming) and reactions that use up hydrogen are exothermic (FCC cracking, hydrogenation, etc.). But why is this so? I know ...
7
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2answers
5k views

What is difference between H⁺ and proton?

What is difference between $\ce{H+}$ and a proton?
5
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2answers
17k views

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 ...
5
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1answer
2k views

Delta G for Standard Hydrogen Electrode reaction

I’m dealing with electrochemistry problems. For the following reaction $$\ce{2H+ +2e- <=>H2}\quad E^\circ=0\ \mathrm{V}$$ Does it make sense to say $$\Delta G^\circ=-nFE^\circ=0$$ Which would ...
3
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1answer
788 views

Deuterium removal from water

What percentage of deuterium might be removed from water after a typical electrolysis procedure? From a post on this site I read that, "In the first stage, $\ce{NaOH}$ solution (initially $0.5\rm{M}$) ...
2
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3answers
5k views

Is it dangerous to inhale the steam coming from electrolysis of salt-water solution

Is chlorine in there that accumulates (at the anode) and emerge out as chlorine gas? I was worried since I added a pinch of salt to the steamer in order to hasten the heating of tap water when I ...
1
vote
1answer
119 views

Production of hydrogen through the reaction of aluminium metal and sodium hydroxide

If I have a solution of 25% $\ce{NaOH}$, and I simply add a cut-up aluminium can or some aluminium foil, will it react into hydrogen and sodium aluminate? In principle this reaction should happen, ...
13
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4answers
24k views

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 ...
10
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1answer
4k views

Can 1 mole of H2 react partially with one mole of O2?

I am currently studying stoichiometry (high school level) and we came across the following equation in school: $\ce{2H2 + 1O2 -> 2H2O}$ which is clear to me. We learned in school that reactions ...
4
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2answers
2k views

Why this doesn't hydrogen peroxide decompose into hydrogen and oxygen?

I'm trying to understand why hydrogen peroxide doesn't decompose into $\ce{H2}$ and $\ce{O2}$, but instead into $\ce{H2O}$ and $\ce{O2}$.
3
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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....
2
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1answer
1k views

Why is there an upper limit to the photon energy that can be observed in the discrete emission spectrum of the hydrogen atom?

I think it must have to do with the fact that an incident photon with a sufficiently high energy will ionize the hydrogen atom (i.e. the electron will be ejected). Therefore it won't show in the ...
1
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0answers
41 views

Limit the production of hydrogen in a small container

I have to produce hydrogen at a near-constant pressure inside of a really small container without using an automatic pressure release value. I would like the pressure to be relatively high, but the ...
1
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3answers
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 ...
1
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1answer
591 views

Difficulty understanding redox in terms of hydrogen and oxygen transfer?

I have come across 4 ways of defining oxidation: loss of electrons increase in oxidation number gain of oxygen loss of hydrogen From these definitions, I have an idea of what I think 'oxidation' and ...
0
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1answer
59 views

How can I neutralise H2 gas without burning it? [closed]

I was thinking of maybe making it bubble into a solution containing something that would react with H2 yielding either a dissolved substance or a precipitate from the reaction. Maybe a solution with ...
-1
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1answer
4k views

Why is the H-H Bond Dissociation Enthalpy so high? [closed]

"The H-H Bond Dissociation Enthalpy is the highest for a single bond between 2 atoms of any element."
-1
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4answers
449 views

Is there any substance that is liquid at room temperature and pressure that doesn't contain H as one it's constituents apart from mercury? [closed]

I want to know if there's any substance that is liquid at room temperature and atmospheric pressure that doesn't contain HYDROGEN atom(s) in its make up. Any substance dissolved in water or any ...
-2
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1answer
254 views

Inorganic reactions related to nascent hydrogen [closed]

Nascent hydrogen is prepared by (A) $\ce{Na}$ and $\ce{C2H5OH}$ (B) $\ce{Al}$ and $\ce{NaOH}$ (C) $\ce{Zn}$ and dil. $\ce{H2SO4}$ (D) All of these My attempt I know that option (A) &...