Animated Solution for Chemistry - Metallurgy: The ore that contains the metal in the form of fluoride is

In the fascinating world of metallurgy, knowing your ores is like knowing the alphabet before writing a novel. Ores are naturally occurring solid materials from which a metal or valuable mineral can be profitably extracted.

When we are faced with a question asking us to identify an ore containing a specific element—in this case, fluorine—we don't need to perform complex thermodynamic calculations or balance intricate redox equations. Instead, we rely on our foundational knowledge of chemical formulas. Let's embark on a journey to decode the chemical identities of the four ores presented to us.

A Chemical Lineup

Let's break down each option systematically to see what elements hide within their crystalline structures.

1. Magnetite: As the name implies, magnetite is a highly magnetic mineral. It is one of the primary ores of iron. Its chemical formula is $F{e}_3{O}_4$. Structurally, it is a mixed oxide containing both $F{e}^{2+}$ and $F{e}^{3+}$ ions. Scanning its formula, we see iron and oxygen, but absolutely no fluorine.

2. Sphalerite: Sphalerite is the chief ore of zinc. It is a sulphide mineral with the chemical formula $ZnS$. In its pure form, it consists entirely of zinc and sulphur. Once again, fluorine is nowhere to be found.

3. Malachite: If you've ever seen antique green copper statues or jewelry, you've likely seen malachite. It is a beautiful, vibrant green mineral that serves as an ore of copper. Chemically, it is a basic copper carbonate with the formula $CuC{O}_3\cdot Cu(OH{)}_2$. It contains copper, carbon, oxygen, and hydrogen. Still, the elusive fluorine remains absent.

4. Cryolite: Finally, we arrive at cryolite. This is a rare and highly valuable mineral. Its IUPAC name is sodium hexafluoroaluminate, and its chemical formula is $N{a}_{3}Al{F}_6$.

Look closely at the end of that formula: $F_6$. There it is! Cryolite contains six fluoride ions per formula unit. Therefore, cryolite is the ore that contains the metal in the form of a fluoride.

Finding the answer is great, but understanding why cryolite is so important is what separates a good student from a great one.

Cryolite is not just a random mineral; it is the unsung hero of the modern aluminium industry. Aluminium is extracted from its primary ore, bauxite, which is purified into alumina ($A{l}_2{O}_3$). To get pure aluminium metal, we must electrolyze this alumina.

However, there is a massive problem: pure alumina has an incredibly high melting point of over $2000^{\circ }C$, and in its molten state, it is a very poor conductor of electricity. Melting it would require an astronomical amount of energy, making the process economically unviable.

The Hall-Heroult Process

Enter the Hall-Heroult process. By mixing alumina with molten cryolite ($N{a}_{3}Al{F}_6$) and a little fluorspar ($Ca{F}_2$), two magical things happen:

1. Melting Point Reduction: The cryolite acts as an impurity, drastically lowering the melting point of the mixture from $2000^{\circ }C$ down to a much more manageable $900^{\circ }C$. 2. Enhanced Conductivity: The molten cryolite dissociates into ions ($N{a}^{+}$, $A{l}^{3+}$, and $F^{-}$), which significantly increases the electrical conductivity of the melt, allowing the electrolysis to proceed smoothly.

By simply recalling the chemical formulas, we easily identified that cryolite ($N{a}_{3}Al{F}_6$) is the only ore among the choices that contains fluorine.

Questions like these are high-yield and highly scoring in competitive exams like JEE and NEET. They reward consistent revision and a solid grasp of fundamental inorganic chemistry. Keep revising your ore tables, and you'll never miss these easy marks!