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

It depends on which definition of acids and bases you are using. According to the Arrhenius theory, acids are defined as a compound or element that releases hydrogen (H+) ions into the solution. ...
Some Name's user avatar
  • 526
28 votes
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At what pressure will hydrogen start to liquefy at room temperature?

$\ce{H2}$ cannot be liquified at room temperature, whatever the pressure. Generally speaking, all gases can only be liquified when the temperature is under its critical value.
Maurice's user avatar
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27 votes

Why does hydrogen burn with a pale blue flame while its emission spectral lines are red in colour?

It is a very interesting question, but comparing a combustion spectrum with an atomic emission one is like comparing apples and oranges. A flame is a luminous gas phase chemical reaction where the ...
AChem's user avatar
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24 votes

At what pressure will hydrogen start to liquefy at room temperature?

The critical temperature of Hydrogen is $\pu{32.938 K, resp. -240.21 ^{\circ}C}$. Above this temperature, it cannot be liquified. So to answer your question, you can get as high pressure as you can ...
Poutnik's user avatar
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23 votes
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Is water a possible fuel for jet engines?

It can't work because of the fundamental thermodynamics What you are proposing is, basically, the plane carries water; the water is broken down into its components, hydrogen and oxygen; the ...
matt_black's user avatar
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22 votes
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Difference between Lindlar and Rosenmund catalysts

This is a rather interesting question because these names actually refer to classes of reactions (specific to certain reagents and products), and aren't constrained by specific proportions of ...
ringo's user avatar
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22 votes
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Why are protons more common than hydride ion?

This is because we live in a world dominated by oxygen and water. In other words, it is an oxidized world. Most metals occur naturally in the form of oxides, silicates, halides, or other derivatives. ...
Ivan Neretin's user avatar
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21 votes

Would sodium explode in salt water?

Yes, sodium metal is also going to react exothermically with salt water or any other aqueous solution as long as it comes in contact with water: $$\ce{Na (s) + H2O -> Na+ (aq) + OH- (aq) + 0.5 H2 (...
andselisk's user avatar
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20 votes

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

You hit it right on the nose. The real key piece of information is that given enough time, all the unsaturated bonds will be reduced. This tells you that though the reduction is thermodynamically ...
ringo's user avatar
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18 votes
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What is the difference between "atomic hydrogen" and "nascent hydrogen"?

Is your book by chance very old? From the Wikipedia entry for "nascent hydrogen": Nascent hydrogen is purported to consist of a chemically reactive form of hydrogen that is freshly generated, ...
airhuff's user avatar
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16 votes
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Why are some elements more abundant than others in the universe?

WHAT MAKES HYDROGEN ABUNDANT IN UNIVERSE: After few minutes of creation of the universe, protons and neutrons began to react with each other to form deuterium, an isotope of hydrogen. Deuterium, soon ...
Yb609's user avatar
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16 votes
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Are there any significant uses of the compound formed by magnesium and anthracene?

It seems like an idea of using magnesium anthracene systems for the $\ce{MgH2}$ production persisted since 1980s [1] till late 2000s, when new more efficient method with better scalability for ...
andselisk's user avatar
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15 votes

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

There are quite a number of theories regarding acidity and basicity, but in this case, will explain the Lewis acid. The Lewis Theory of acids and bases This theory extends well beyond the things you ...
xavier_fakerat's user avatar
14 votes
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Which gas is a oxidizing agent as well as a reducing agent?

I'm guessing your teacher is looking for sulfur dioxide as the answer, but I don't see how or why you're supposed to be able to arrive to this answer logically. Either you'd need to read about it ...
Nicolau Saker Neto's user avatar
13 votes
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Can hydrogen peroxide reduce ferric ion to ferrous ion?

You are right. This question is "practically" incorrect, although on paper it might appear so if someone is unaware of real chemistry (the question setter). Iron (II) will readily ...
AChem's user avatar
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12 votes

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

This issue is discussed in the following references: Hydrogenation of chalcones using hydrogen permeating through a Pd and palladized Pd electrodes Electrochimica Acta vol. 55, pages 5831–5839. and ...
DavePhD's user avatar
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12 votes
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Is there a reaction to get hydrogen from hydrocarbons?

Hydrocarbons are in fact the main source of hydrogen gas. According to Wikipedia, 95% of all hydrogen is produced by the steam reforming reaction: $$\ce{CH4(g) + H2O(g) -> 3H2(g) + CO(g)}$$ This ...
Nicolau Saker Neto's user avatar
12 votes
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Why do spin isomers of hydrogen (ortho and para hydrogen) change their nuclear spin with temperature variance?

The effect is due to the symmetry properties of the rotational energy levels and those of the nuclear spin. The change with temperature is, as usual, traced back to the Boltzmann distribution. In ...
porphyrin's user avatar
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11 votes
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Chemical equation that can be balanced in infinite number of ways?

We first note that your reaction (4) can be broken down into two reactions by splitting up those chemical species that depend on $n$ and those that don't: $$\begin{align}\ce{CH4 + H2O &-> CO + ...
a-cyclohexane-molecule's user avatar
11 votes
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Is a hydrogen molecule smaller than hydrogen atom?

You can define the size of atoms and molecules in various ways. You can, for instance, derive a measure of the size of a hydrogen molecule from the density of solid hydrogen: Solid hydrogen has a ...
Buck Thorn's user avatar
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11 votes
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Radius of hydride (H⁻) ion

Unfortunately, there is no caliper-like tool to measure ionic radii directly. They are determined based on experimental data such as crystal structure or crystal lattice energy using empirical ...
andselisk's user avatar
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10 votes

Why is there no neutron in protium?

@Jan's put up a nice and crisp, answer. My answer is merely a supplement to that ;) It's because the hydrogen ("protium", if you will) nucleus has no need for neutrons. What's this "need for ...
paracetamol's user avatar
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10 votes
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What is the nature of interstitial hydrides?

Nonstoichiometric compounds are simply compounds that cannot be represented with integer number of atoms. What the book probably is trying to say is that the hydrogen atoms do not simply fill the ...
CoffeeIsLife's user avatar
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10 votes

Smell produced in reaction of sodium hydroxide and aluminium

Oscar Lanzi's answer addressed the points correctly. This reaction of Al + NaOH pellets is used in drain openers for obvious reasons. The reaction is so exothermic that solution can start boiling. It ...
AChem's user avatar
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9 votes

Why does hydrogen burn with a pop sound?

We may agree that during the combustion, regardless if the one of wood, gasoline, or in your example, hydrogen gas, is an exothermic reaction. In a simplified view, products of these reaction are ...
Buttonwood's user avatar
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9 votes

What bond exists in "red oxygen", and can something similar happen with hydrogen?

That is what I found on wikipedia. It has a cubic structure and it was not predicted theoretically. here the pressure is not very high but is high(10 GPa) High-pressure studies of hydrogen typically ...
amish dua's user avatar
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9 votes

Why are protons more common than hydride ion?

Actually, $\ce{H^-}$ is relatively common in organic chemistry. Carbocation rearrangement is often done through a hydride ion transfer within the ion, and hydride-ion transfers are featured in organic ...
Oscar Lanzi's user avatar
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8 votes
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H2 Triplet State

Assuming that you're talking about electronically excited states and not spin isomers of the $\ce{H2}$ molecule (as anticipated by Ivan Neretin), note first that there are many triplet states, of ...
Wildcat's user avatar
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8 votes

Hydrogenation side product: potential mechanisms for C-C bond making

First of all, I would check for impurities in styreneoxide. There is a good chance it was prepared from styrene having some 2-phenylpropylene in it, and this could account for your impurity. Other ...
permeakra's user avatar
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8 votes
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Hydrogen atom transfer between enantiomers of rac-1-phenylethanol

Did you continue reading the paper? :) The source is important and is what was needed to answer the question! I'm just going to quote from it. In DKR [dynamic kinetic resolution] a chemical ...
orthocresol's user avatar
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