Question

What is Misch metal? Give its composition and uses.

Answer 1

Hint : It is an alloy of various metals. One of the elements belongs to the lanthanide series.

Complete step by step solution :
The word “Misch metal” actually has German origins. It is composed of two German words “mischen” which means “to mix” and “metall” as in a “metal”. This is an alloy composed of rare earth elements along with other metals which are widely used such as iron.
Misch metal is actually special because one of its major constituents is Lanthanum which is the first element of the lanthanide series. It is one of the inner transition elements where the last electron enters into $4f$orbital. Lanthanum has an atomic number of 57 and is represented as “La'' These elements are radioactive in nature.

Misch metal has a different composition of its constituent elements depending upon where it is used. The most common one out of them consists of $50$ cerium and $25$lanthanum along with other rare earth elements in smaller amounts such as neodymium, praseodymium and others in trace amounts to complete the whole.
The rare earth metal industry is younger than the normal metal industry as the former is difficult to procure and purify which makes it not-so-fit for widespread use. These rare metals most of the time are radioactive and unstable making them dangerous.
The first misch metal was extracted from monazite ore and from then on the rare earth metal industry has boomed.

Unlike the other metals belonging to d-block, f-block metals are soft and brittle and they readily oxidised or absorb other elements present in the atmosphere which make them impure and difficult to research upon.
von Welsbach was one of the first to produce misch metal by fusing cerium and iron through the process of electrolysis. This gave the alloy hardness and therefore stability. This happened in the early twentieth century and from then on the industry has developed to what it is today. China is the largest producer of misch metals.

Uses of misch metal include:
- In vacuum tube manufacturing misch metals are used to remove oxygen
- Batteries that work upon metal hydride technology use misch metals
- Misch metals can easily produce sparks when struck with and therefore they are used in cigarette lighters and similar devices
- They are used in other alloys to improve the physical properties as well as castability
- Used in movies to add special effects

Note : Misch metals are not any normal alloys. One of the constituents has to be a rare-earth metal belonging to the lanthanide or actinide series. The rare-earth metal/metals has/have to be one of the major components.