Praseodymium is used in carbon arc lights

and in color is silvery white

 

 

Historical Background
In 1841, Swedish chemist Carl Gustaf Mosander extracted the rare earth element didymia from lanthana.  In 1879, French chemist Paul Emile Lecoq de Boisbaudran isolated a new earth, samaria, from didymia obtained from the mineral samarskite. Six years later, in 1885, a German chemist named Carl F. von Welsbach separated didymium into two elements, praseodymium and neodymium.  Praseodymium occurs along with other rare-earth elements in a variety of minerals, but monazite and bastnasite are the two main commercial sources. Praesodymium was prepared in relatively pure form in 1931.  Today, praseodymium is mostly obtained through an ion exchange process from monazite sand, a material rich in rare earth elements. 

Uses
Praseodymium's main use is as an alloying agent with magnesium to create high-strength metals that are used in aircraft engines. Praseodymium also makes up about 5% of Misch metal, a material that is used to make flints for cigarette lighters. Praseodymium forms the core of carbon arc lights that are used in the motion picture industry for studio lighting and projector lights. Praseodymium is added to fiber optic cables as a signal amplifier. Praseodymium salts are used to give glasses and enamels a yellow color. Praseodymium is also a component of didymium glass, which is used to make goggles for welders and glass blowers.

Environmental Impact

Praseodymium is dumped in many different places in the environment, mainly dumped in those places by the petrol-making companies. It can also get into the environment when household equipment is thrown away. The element will gradually collect in soils, above water and underwater, which leads to increasing populations in humans, animals and soil particles. With creatures who live in water, praseodymium causes damage to cell membranes. This damage has a lot of bad influences on reproduction and the functions of the nervous system.
Properties
Praseodymium is soft, malleable and ductile. It is silvery white in color, but it does develop a green oxide coating, which crumbles when it is exposed to oxygen. Praseodymium is also slightly more resistant to corrosion in the air than europium, lanthanum, cerium or neodymium. It reacts slowly to oxygen and cold water, and reacts quickly to hot water. In air, it tarnishes slowly, and in water it reacts to form praseodymium hydroxide. It is a rare-earth metal, so it should be kept under a light mineral oil or sealed in plastic.

Table
Protons 59
Neutrons 82
Electrons 59
Classification Rare-earth metal
Symbol Pr
Atomic Mass 140.907
Melting Point 931 degrees Celcius
Boiling Point 3520 degrees Celcius
Density 6.77 grams per cubic centimeter
State Solid
Period Number 6
Name From the Greek words prasios + didymos, which mean "green twin"

 

Praseodymium slowly tarnishes when exposed to Oxygen. To find out more about Oxygen, go to the Oxygen webpage

 

Glossary
 

Samarskite: a mineral that varies in color from black to yellowish brown

Misch Metal: a pyrophoric alloy which contains 50 percent cerium and 45 percent lanthanum; is made from a mixture of assorted rare-earth chlorides through electrolysis

Malleable: able to be hammered or pressed permanently out of shape

Ductile: able to be drawn out into a thin wire

Carbon: a widely occurring element that forms organic compounds when combined with oxygen, hydrogen, etc.

Oxide: a binary compound of oxygen with another element or group 

Corrosion: the process of slow damage by chemical action 

 

Bibliography
 

Stwertka, Albert. A Guide to the Elements. New York, New York: Oxford University Press Inc. 1996.

Emsley, John. The Elements. New York: Oxford University Press Inc.,1992.

Thompson, Larry C. World Book Encyclopedia. Chicago, Illinois: World Book Inc., 2008.

University of California. “praseodymium.” Feb. 4, 2008. Los Alamos National Labs Chemistry Division.  http://www.periodic.lan.gov/elements159.html>

Mark Winter. “Praseodymium: the essentials.” Feb. 4, 2008. Web Elements. http://www.webelements.com/praseodymium/

Kenneth L. Barbalace. “Element Praseodymium-Pr.” Feb. 4, 2008. Environmental Chemistry.com. http://environmentalchemistry.com/yogl/periodic/Pr.html


Back to Top of Page