Question

What are alloys? Name an important alloy which contains some of the lanthanoid metals. Mention its uses.

Answer 1

Hint: Alloys are the homogeneous solid solutions in which the atoms of one metal are distributed randomly among the atoms of the other metal. The Lanthanides are the inner transition elements and are found in nature in combined form. One such combined form is the alloy of cerium, lanthanum and some other rare metals.

Complete answer:
 In an alloy, the atoms of a similar crystal lattice try to accommodate with the atoms of another crystal lattice. In case of transition metals, the atoms of one metal try to substitute the atoms of other metal in its crystal lattice. Similarly, in the case of lanthanides, only those elements can form an alloy which has comparatively similar sizes of atoms and the atoms of one element can substitute the atoms of another crystal lattice of a different lanthanide element.
An important alloy which contains some of the lanthanoid metals is the misch metal. It is an alloy of cerium, lanthanum and other rare earth metals.
Some of the uses of misch metal are:
(i) It is used in the flints for cigarette lighters.
(ii) It is used as a deoxidizer in vacuum tubes.
(iii) It is used as an alloying agent in magnesium to contribute high strength and low resistance.

Note:
 A misch metal has a series of lanthanide elements and has a variety of metallurgical applications. Although the lanthanides cannot exist in free state, it is possible for them to exist in the form of combined state such as in this kind of alloy.