# 18.5 Occurrence, preparation, and compounds of hydrogen  (Page 3/9)

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Chemical Reactions of Hydrogen with Other Elements
${\text{MH or MH}}_{2}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{MOH or M}{\left(\text{OH}\right)}_{2}+{\text{H}}_{2}$ ionic hydrides with group 1 and Ca, Sr, and Ba
${\text{H}}_{2}+\text{C}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{(no reaction)}$
${\text{3H}}_{2}+{\text{N}}_{2}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{2NH}}_{3}$ requires high pressure and temperature; low yield
${\text{2H}}_{2}+{\text{O}}_{2}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{2H}}_{2}\text{O}$ exothermic and potentially explosive
${\text{H}}_{2}+\text{S}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{H}}_{2}\text{S}$ requires heating; low yield
${\text{H}}_{2}+{\text{X}}_{2}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{2HX}$ X = F, Cl, Br, and I; explosive with F 2 ; low yield with I 2

## Reaction with compounds

Hydrogen reduces the heated oxides of many metals, with the formation of the metal and water vapor. For example, passing hydrogen over heated CuO forms copper and water.

Hydrogen may also reduce the metal ions in some metal oxides to lower oxidation states:

${\text{H}}_{2}\left(g\right)\phantom{\rule{0.2em}{0ex}}+\phantom{\rule{0.2em}{0ex}}{\text{MnO}}_{2}\left(s\right)\phantom{\rule{0.2em}{0ex}}\stackrel{\phantom{\rule{0.4em}{0ex}}\text{Δ}\phantom{\rule{0.4em}{0ex}}}{\to }\phantom{\rule{0.2em}{0ex}}\text{MnO}\left(s\right)+{\text{H}}_{2}\text{O}\left(g\right)$

## Hydrogen compounds

Other than the noble gases, each of the nonmetals forms compounds with hydrogen. For brevity, we will discuss only a few hydrogen compounds of the nonmetals here.

## Nitrogen hydrogen compounds

Ammonia, NH 3 , forms naturally when any nitrogen-containing organic material decomposes in the absence of air. The laboratory preparation of ammonia is by the reaction of an ammonium salt with a strong base such as sodium hydroxide. The acid-base reaction with the weakly acidic ammonium ion gives ammonia, illustrated in [link] . Ammonia also forms when ionic nitrides react with water. The nitride ion is a much stronger base than the hydroxide ion:

${\text{Mg}}_{3}{\text{N}}_{2}\left(s\right)\phantom{\rule{0.2em}{0ex}}+\phantom{\rule{0.2em}{0ex}}{\text{6H}}_{2}\text{O}\left(l\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{3Mg}{\left(\text{OH}\right)}_{2}\left(s\right)+{\text{2NH}}_{3}\left(g\right)$

The commercial production of ammonia is by the direct combination of the elements in the Haber process    :

${\text{N}}_{2}\left(g\right)+{\text{3H}}_{2}\left(g\right)\stackrel{\phantom{\rule{0.2em}{0ex}}\text{catalyst}\phantom{\rule{0.2em}{0ex}}}{\text{⇌}}{\text{2NH}}_{3}\left(g\right)\phantom{\rule{5em}{0ex}}\text{Δ}H\text{°}=\text{−92 kJ}$

Ammonia is a colorless gas with a sharp, pungent odor. Smelling salts utilize this powerful odor. Gaseous ammonia readily liquefies to give a colorless liquid that boils at −33 °C. Due to intermolecular hydrogen bonding, the enthalpy of vaporization of liquid ammonia is higher than that of any other liquid except water, so ammonia is useful as a refrigerant. Ammonia is quite soluble in water (658 L at STP dissolves in 1 L H 2 O).

The chemical properties of ammonia are as follows:

1. Ammonia acts as a Brønsted base, as discussed in the chapter on acid-base chemistry. The ammonium ion is similar in size to the potassium ion; compounds of the two ions exhibit many similarities in their structures and solubilities.
2. Ammonia can display acidic behavior, although it is a much weaker acid than water. Like other acids, ammonia reacts with metals, although it is so weak that high temperatures are necessary. Hydrogen and (depending on the stoichiometry) amides (salts of ${\text{NH}}_{2}{}^{\text{−}}\right),$ imides (salts of NH 2− ), or nitrides (salts of N 3− ) form.
3. The nitrogen atom in ammonia has its lowest possible oxidation state (3−) and thus is not susceptible to reduction. However, it can be oxidized. Ammonia burns in air, giving NO and water. Hot ammonia and the ammonium ion are active reducing agents. Of particular interest are the oxidations of ammonium ion by nitrite ion, ${\text{NO}}_{2}{}^{\text{−}},$ to yield pure nitrogen and by nitrate ion to yield nitrous oxide, N 2 O.
4. There are a number of compounds that we can consider derivatives of ammonia through the replacement of one or more hydrogen atoms with some other atom or group of atoms. Inorganic derivations include chloramine, NH 2 Cl, and hydrazine, N 2 H 4 :

how do u derive this fundamental constants
am not sure how
Shehu
do you have an idea
Shehu
no
Mugala
Bertram
could you elaborate a little more on your question?
Jallal
or reword it perhaps. I think I understand what you're trying to ask but the wording of the question makes it confusing
Jallal
what fundamental constants?
Ruth
you see Bertran. if you can do a little more explaining on what you are trying to have answered there wouldn't be so much confusion and you'd most likely get your answer your searching for
Jallal
Bertram*
Jallal
what is an atom
An atom is the smallest indivisible particle of an element that is capable of independent existence
akinboboye
That's conventional thinking since the Greeks and our current teaching, but it's been discovered that atoms are made up of even smaller subatomic particles called "quarks". Until fully understood let's stick with the current knowledge that an atom is the smallest unit of mass being indivisible
Jallal
What is rightful definition of element
an element is the group of (vertical columns) of the periodic table exhibit similar chemical behaviour.
Barnabas
okay
angela
is alkanes a saturated hydrocarbon?
yup
it's saturated cos it has single bonds
yh....because they don't undergo additional reactions which hydrogen and other atoms can add across the carbon-carbon or triple bond
patience
and me...I'm I wrong?
patience
how does metal looses electron
By oxidation and reduction
hamidat
by oxidation loss
Official
An acid is a proton donor.
what is an acid
an acid is a substance when dissolved in water produces hydrogen ion or hydroxonium ion
hamidat
good
Mudassir
thanks
hamidat
is a substance which dissolves in water to produce hydrogen ions as the only positively charged ions
Kwagala
what is ionic bonding
It involves the transferring of electron from a metal to a non mental
hamidat
that's right
Edward
bonding between a metal and a non metal
miriam
calculate the hydrogen ion concentration of the solution when pH=5
What is thermodynamics
what is the meaning this word twentieth
dhu
Is the branch of physics that deal with heat and temperature and their relation to work, energy and properties of matter
Edward
There are no topics on hydrocarbons
they are there please check under organic chemistry in the contents.
Kwagala
its not making sense to me I still don't understand
How and why
Betrice
yes
megan
we need diagram for easy going and understand
serah
How can we easily differentiate between the 5 gas laws
first amd foremist me i only know 3 gas laws, so please list them here
Kwagala
the gas laws i know include pressure law boyles law charles law i differentiate these with this formular big take classy pork pigs. viral i read thus as 1 big classy pigs take pork viral big.....take means in boyles law,temp is constant clasy.....prk mns in chrls lw, press cons
Kwagala
classy.....pork means in charles law pressure is constant pigs.....viral means, in pressure law volume is kept constsng ,the rest is the same boyles states that vol of a gas is inversely prop to volume keeping temp constant charles law, state vol of a gas is directly prop to temp keepn pressure cns
Kwagala
how many carbon is present in alkene
it's the carbon to carbon being double bonded to each other that makes it an alkene, not the amount of carbon itself. ex: C=C, C=C=C. both are alkenes.
Phill
I need more light on alkene
chidera
an alkene is a hydrocarbon, you can find this under the sub topic of organic chemistry in this textbook, check it out please,but before you know about alkenes you should first know about alkanes, alkanes are saturated and dnt easily react while alkenes have double bonds and can react .
Kwagala
other usefullness of hydrogen apart from this, it is colourless, odourless and tasteless
it is neutral to litmus paper, it is insoluble in water
hamidat