# 18.12 Occurrence, preparation, and properties of the noble gases  (Page 2/4)

 Page 2 / 4

Argon was useful in the manufacture of gas-filled electric light bulbs, where its lower heat conductivity and chemical inertness made it preferable to nitrogen for inhibiting the vaporization of the tungsten filament and prolonging the life of the bulb. Fluorescent tubes commonly contain a mixture of argon and mercury vapor. Argon is the third most abundant gas in dry air.

Krypton-xenon flash tubes are used to take high-speed photographs. An electric discharge through such a tube gives a very intense light that lasts only $\frac{1}{50,000}$ of a second. Krypton forms a difluoride, KrF 2 , which is thermally unstable at room temperature.

Stable compounds of xenon form when xenon reacts with fluorine. Xenon difluoride, XeF 2 , forms after heating an excess of xenon gas with fluorine gas and then cooling. The material forms colorless crystals, which are stable at room temperature in a dry atmosphere. Xenon tetrafluoride, XeF 4 , and xenon hexafluoride, XeF 6 , are prepared in an analogous manner, with a stoichiometric amount of fluorine and an excess of fluorine, respectively. Compounds with oxygen are prepared by replacing fluorine atoms in the xenon fluorides with oxygen.

When XeF 6 reacts with water, a solution of XeO 3 results and the xenon remains in the 6+-oxidation state:

${\text{XeF}}_{6}\left(s\right)+{\text{3H}}_{2}\text{O}\left(l\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{XeO}}_{3}\left(aq\right)+\text{6HF}\left(aq\right)$

Dry, solid xenon trioxide, XeO 3 , is extremely explosive—it will spontaneously detonate. Both XeF 6 and XeO 3 disproportionate in basic solution, producing xenon, oxygen, and salts of the perxenate ion, ${\text{XeO}}_{6}{}^{4-},$ in which xenon reaches its maximum oxidation sate of 8+.

Radon apparently forms RnF 2 —evidence of this compound comes from radiochemical tracer techniques.

Unstable compounds of argon form at low temperatures, but stable compounds of helium and neon are not known.

## Key concepts and summary

The most significant property of the noble gases (group 18) is their inactivity. They occur in low concentrations in the atmosphere. They find uses as inert atmospheres, neon signs, and as coolants. The three heaviest noble gases react with fluorine to form fluorides. The xenon fluorides are the best characterized as the starting materials for a few other noble gas compounds.

## Chemistry end of chapter exercises

Give the hybridization of xenon in each of the following. You may wish to review the chapter on the advanced theories of covalent bonding.

(a) XeF 2

(b) XeF 4

(c) XeO 3

(d) XeO 4

(e) XeOF 4

(a) sp 3 d hybridized; (b) sp 3 d 2 hybridized; (c) sp 3 hybridized; (d) sp 3 hybridized; (e) sp 3 d 2 hybridized;

What is the molecular structure of each of the following molecules? You may wish to review the chapter on chemical bonding and molecular geometry.

(a) XeF 2

(b) XeF 4

(c) XeO 3

(d) XeO 4

(e) XeOF 4

Indicate whether each of the following molecules is polar or nonpolar. You may wish to review the chapter on chemical bonding and molecular geometry.

(a) XeF 2

(b) XeF 4

(c) XeO 3

(d) XeO 4

(e) XeOF 4

(a) nonpolar; (b) nonpolar; (c) polar; (d) nonpolar; (e) polar

What is the oxidation state of the noble gas in each of the following? You may wish to review the chapter on chemical bonding and molecular geometry.

(a) XeO 2 F 2

(b) KrF 2

(c) ${\text{XeF}}_{3}{}^{+}$

(d) ${\text{XeO}}_{6}{}^{4-}$

(e) XeO 3

A mixture of xenon and fluorine was heated. A sample of the white solid that formed reacted with hydrogen to yield 81 mL of xenon (at STP) and hydrogen fluoride, which was collected in water, giving a solution of hydrofluoric acid. The hydrofluoric acid solution was titrated, and 68.43 mL of 0.3172 M sodium hydroxide was required to reach the equivalence point. Determine the empirical formula for the white solid and write balanced chemical equations for the reactions involving xenon.

The empirical formula is XeF 6 , and the balanced reactions are:
$\begin{array}{}\\ \\ \text{Xe}\left(g\right)+{\text{3F}}_{2}\left(g\right)\phantom{\rule{0.2em}{0ex}}\stackrel{\phantom{\rule{0.4em}{0ex}}\text{Δ}\phantom{\rule{0.4em}{0ex}}}{\to }\phantom{\rule{0.2em}{0ex}}{\text{XeF}}_{6}\left(s\right)\\ {\text{XeF}}_{6}\left(s\right)+{\text{3H}}_{2}\left(g\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{6HF}\left(g\right)+\text{Xe}\left(g\right)\end{array}$

Basic solutions of Na 4 XeO 6 are powerful oxidants. What mass of Mn(NO 3 ) 2 •6H 2 O reacts with 125.0 mL of a 0.1717 M basic solution of Na 4 XeO 6 that contains an excess of sodium hydroxide if the products include Xe and solution of sodium permanganate?

what are ionic compound
where can I find the Arrhenius equation
ln(k two/k one)= (- activation energy/R)(1/T two - 1/T one) T is tempuratue in Kelvin, K is rate constant but you can also use rate two and one instead, R is 8.314 J/mol×Kelvin
Drenea
if ur solving for k two or k one you will need to use e to cancel out ln
Drenea
what is an atom
An atom is the smallest particle of an element which can take part in a chemical reaction..
olotu
hello
Karan
how to find the rate of reaction?
Karan
what is isomerism ?
Formula for equilibrium
is it equilibrium constant
olotu
Yes
Olatunde
yes
David
what us atomic of molecule
chemical formula for water
H20
Samson
what is elemental
what are the properties of pressure
Maryam
How can water be turned to gas
VICTOR
what's a periodic table
this can be defined as the systematic way of arranging element into vertical spaces called periods and horizontal spaces called groups on a table
onwuchekwa
how does carbon catenate?
condition in cracking from Diesel to petrol
hey I don't understand anything in chemistry so I was wondering if you could help me
i also
Okikiola
I also
Brient
hello
Brient
condition for cracking diesel to form kerosene
Brient
Really?
Isa
yes
Brient
can you tell me
Brient
Brient
what is periodic law
periodic law state that the physical and chemical properties of an element is the periodic function of their atomic number
rotimi
how is valency calculated
How is velency calculated
Bankz
Hi am Isaac, The number of electrons within the outer shell of the element determine its valency . To calculate the valency of an element(or molecule, for that matter), there are multiple methods. ... The valency of an atom is equal to the number of electrons in the outer shell if that number is fou
YAKUBU
what is the oxidation number of this compound fecl2,fecl3,fe2o3