# 18.5 Occurrence, preparation, and compounds of hydrogen  (Page 4/9)

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Chloramine, NH 2 Cl, results from the reaction of sodium hypochlorite, NaOCl, with ammonia in basic solution. In the presence of a large excess of ammonia at low temperature, the chloramine reacts further to produce hydrazine, N 2 H 4 :

${\text{NH}}_{3}\left(aq\right)+{\text{OCl}}^{\text{−}}\left(aq\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{NH}}_{2}\text{Cl}\left(aq\right)+{\text{OH}}^{\text{−}}\left(aq\right)$
${\text{NH}}_{2}\text{Cl}\left(aq\right)+{\text{NH}}_{3}\left(aq\right)+{\text{OH}}^{\text{−}}\left(aq\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}{\text{H}}_{4}\left(aq\right)+{\text{Cl}}^{\text{−}}\left(aq\right)+{\text{H}}_{2}\text{O}\left(l\right)$

Anhydrous hydrazine is relatively stable in spite of its positive free energy of formation:

${\text{N}}_{2}\left(g\right)+{\text{2H}}_{2}\left(g\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}{\text{H}}_{4}\left(l\right)\phantom{\rule{5em}{0ex}}{\text{Δ}G}_{\text{f}}^{°}=149.2\phantom{\rule{0.2em}{0ex}}\text{kJ}\phantom{\rule{0.2em}{0ex}}{\text{mol}}^{-1}$

Hydrazine is a fuming, colorless liquid that has some physical properties remarkably similar to those of H 2 O (it melts at 2 °C, boils at 113.5 °C, and has a density at 25 °C of 1.00 g/mL). It burns rapidly and completely in air with substantial evolution of heat:

${\text{N}}_{2}{\text{H}}_{4}\left(l\right)+{\text{O}}_{2}\left(g\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}\left(g\right)+{\text{2H}}_{2}\text{O}\left(l\right)\phantom{\rule{5em}{0ex}}\text{Δ}H\text{°}=-621.5\phantom{\rule{0.2em}{0ex}}\text{kJ}\phantom{\rule{0.2em}{0ex}}{\text{mol}}^{-1}$

Like ammonia, hydrazine is both a Brønsted base and a Lewis base, although it is weaker than ammonia. It reacts with strong acids and forms two series of salts that contain the ${\text{N}}_{2}{\text{H}}_{5}{}^{+}$ and ${\text{N}}_{2}{\text{H}}_{6}{}^{2+}$ ions, respectively. Some rockets use hydrazine as a fuel.

## Phosphorus hydrogen compounds

The most important hydride of phosphorus is phosphine, PH 3 , a gaseous analog of ammonia in terms of both formula and structure. Unlike ammonia, it is not possible to form phosphine by direct union of the elements. There are two methods for the preparation of phosphine. One method is by the action of an acid on an ionic phosphide. The other method is the disproportionation of white phosphorus with hot concentrated base to produce phosphine and the hydrogen phosphite ion:

$\text{AlP}\left(s\right)+{\text{3H}}_{3}{\text{O}}^{\text{+}}\left(aq\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{PH}}_{3}\left(g\right)+{\text{Al}}^{3+}\left(aq\right)+{\text{3H}}_{2}\text{O}\left(l\right)$
${\text{P}}_{4}\left(s\right)+{\text{4OH}}^{\text{−}}\left(aq\right)+{\text{2H}}_{2}\text{O}\left(l\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{2HPO}}_{3}{}^{2-}\left(aq\right)+{\text{2PH}}_{3}\left(g\right)$

Phosphine is a colorless, very poisonous gas, which has an odor like that of decaying fish. Heat easily decomposes phosphine $\left({\text{4PH}}_{3}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{P}}_{4}+{\text{6H}}_{2}\right),$ and the compound burns in air. The major uses of phosphine are as a fumigant for grains and in semiconductor processing. Like ammonia, gaseous phosphine unites with gaseous hydrogen halides, forming phosphonium compounds like PH 4 Cl and PH 4 I. Phosphine is a much weaker base than ammonia; therefore, these compounds decompose in water, and the insoluble PH 3 escapes from solution.

## Sulfur hydrogen compounds

Hydrogen sulfide, H 2 S, is a colorless gas that is responsible for the offensive odor of rotten eggs and of many hot springs. Hydrogen sulfide is as toxic as hydrogen cyanide; therefore, it is necessary to exercise great care in handling it. Hydrogen sulfide is particularly deceptive because it paralyzes the olfactory nerves; after a short exposure, one does not smell it.

The production of hydrogen sulfide by the direct reaction of the elements (H 2 + S) is unsatisfactory because the yield is low. A more effective preparation method is the reaction of a metal sulfide with a dilute acid. For example:

$\text{FeS}\left(s\right)+{\text{2H}}_{3}{\text{O}}^{\text{+}}\left(aq\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{Fe}}^{2+}\left(aq\right)+{\text{H}}_{2}\text{S}\left(g\right)+{\text{2H}}_{2}\text{O}\left(l\right)$

It is easy to oxidize the sulfur in metal sulfides and in hydrogen sulfide, making metal sulfides and H 2 S good reducing agents. In acidic solutions, hydrogen sulfide reduces Fe 3+ to Fe 2+ , ${\text{MnO}}_{4}{}^{-}$ to Mn 2+ , ${\text{Cr}}_{2}{\text{O}}_{7}{}^{2-}$ to Cr 3+ , and HNO 3 to NO 2 . The sulfur in H 2 S usually oxidizes to elemental sulfur, unless a large excess of the oxidizing agent is present. In which case, the sulfide may oxidize to ${\text{SO}}_{3}{}^{2-}$ or ${\text{SO}}_{4}{}^{2-}$ (or to SO 2 or SO 3 in the absence of water):

please what is a lightening thunder?
wat are hydrocarbon s
I think they are molecules that comprise only of hydrogen and carbon atoms ( they are organic if I'm not mistaken)
Mmathabo
am new here can I join
Yeko
yes u can
Benita
give two properties of liquid
molecules are slightly packed and they follow the shape of a container.
Obedie
Onimisi
hi
Ajipha
hello
Yeko
two: you can slip your fat arse by stepping on it 😁
anyone with notes of ionic equilibrium
Yeko
what is measurement
is the comparison of an unknown quantity with a fixed quantity of the same kind
How does an element differ from a compound? How are they similar?
an element is an indivisible particles that can take part in a reaction and consist of smaller or tiny particles i.e proton, neutrons and electron while a compound is when two or more element chemically combine together. They are similar when they are homogeneous compound. they take the same rxn.
Yusuf
an element is s chemically pure substance containing a particular type of atoms.. A COMPOUND is a substance containing atoms from different elements..
Inemesit
How to get the Lewis formula of SeCl+3
hi,I'm new here can I join the conversation
EZEA
what is the structural formula for starch
Starch is a mixture (of chemicals) of amylose and amylopectin. Both are macromolecules and polymers. You can search on wikipedia.
Abdelkarim
what is the roles of filter bed
Fathmat
what is the roles of Alu m
Fathmat
what is the roles of chlorine
Fathmat
Roles can be classified or correlate it to different areas: For example: Chlorine can be used in reactions (in industry) to manufacture HCl, which then can be used for other things. Or in swimming pools to kill bacteria. Or as a component in compounds with pharmaceutical roles (drugs). For Al:
Abdelkarim
Its dentisty value is suitable to be used in alloys (mixture of metals) in aircraft bodies. Also, Aluminium foils, Tin cans,.. Some of them are also in Al overhead cables in streets and long roads.
Abdelkarim
what is chemistry
Maxamed
what is the meaning of exceedingly
it is an adverb which means extremely
Rohini
what is atomic chemistry?
Lewis structure for no3
Lewis structure for no3
Yes
Gillian
Lewis structure for no3
Nomvelo
what is weak acid
It is an acid which partially ionises in water.
Abdelkarim
what is incandescence
Clifton
what makes it glow
Clifton
why is it red, irange and yellow in color
Clifton
hello am new here and I want to join you
Aliyu
hello
Clifton
hi
Aliyu
too
Gillian
hello i am new here please i want to join this group
Paul
Hi, I'm also new here
Salaudeen
Hi
Keeya
hello guys !!
Sourav
what is pressure?
The force applied to suction Area of the body
Ahmed
Matter composed of exceedingly small paticle called atom.
Yushao
questions related to metals
occurrence and preparation of the representatives metals
Regina
list the 20, periodic table and their symbols
hydrogen:h helium;he lithium:l beryllium:be Boron:b Carbon;C Nitrogen:n Oxygen:O FLUORINE:f Neon:n Sodium:s Magnesium:mg Aluminum:a Silicon:s Phosphorus:p Sulphur:s Chlorine:c Argon;a Potassium:p Calcium:c
Benita
Hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, neon, sodium, magnesium, aluminium, silicon, phosphorus, sulphur, chlorine, argon, potassium, calcium
Cudjoe
Welcome
Gillian
there are 118 known elements ...you numbnuts
what is a solute
Any substance that is disolved in a liqid solvent to create a solution
Fifa
sorry liquid
Fifa
it's a liquid substance
Fathmat
hello group
Ayomide
is the substance that dissolves in the solvent
Amos
so is HCl ionic compound
No, covalent compound ➡️ molecule. As both H and Cl are non-metals and and form covalent bind by sharing valence e-. But can fully ionice in water forming H+ (a proton, a reason for acidity) and Cl- (anion =Chloride) Hydrogen Chloride is a gas at room; Hydrochloric acid = HCl (aq), dissolved in w
Abdelkarim
Form covalenr bond*
Abdelkarim
The question marks are an emoji in the first sentence is an unread emoji. HCl Covalent compund -> molecule
Abdelkarim
Hi.
Queen
Hi
Calvin
Yh
Cudjoe
yes
Amos