Question

Write the formula and calculate the molar mass of ferric chloride.

Answer 1

Ferric chloride is an inorganic compound.It consists of two elements one is iron (${\text{Fe}}$) and chlorine (${\text{Cl}}$). It is generally prepared from ferrous chloride by the action of chloride or nitric acid. And it is widely used in water purification and for sewage treatment.

Complete step by step answer:
It is already said that Ferric chloride is an inorganic compound, with a formula of ${\text{FeC}}{{\text{l}}_3}$. Consisting of one ${\text{Fe}}$ atom and three ${\text{Cl}}$ atoms. Ferric chloride iron is in $+ 3$oxidation state. It is also known as molysite.
The molar mass is the mass of a given molecule or compound, it is measured in ${\text{g}}\,{\text{mo}}{{\text{l}}^{ - 1}}$. The characteristic molar mass of an element is atomic mass in ${\text{g}}\,{\text{mo}}{{\text{l}}^{ - 1}}$. It can also be calculated by multiplying atomic mass in ${\text{amu}}$ with Avogadro number. In order to calculate the molar mass of a compound having multiple atoms we have to take the sum of all the atomic mass of constituent atoms.
Here in ${\text{FeC}}{{\text{l}}_3}$, we can calculate the molar mass by taking the sum of atomic mass of one ${\text{Fe}}$ atom and three ${\text{Cl}}$atoms. Atomic mass of ${\text{Fe}}$ atom is given by $55.8\,{\text{g}}$ and that of ${\text{Cl}}$ is ${\text{35}}{\text{.5}}\,{\text{g}}$. In ${\text{FeC}}{{\text{l}}_3}$ there is one ${\text{Fe}}$ atom and three ${\text{Cl}}$ atoms.
Molar mass of ${\text{FeC}}{{\text{l}}_3}$= $55.8\, \times \left( {3 \times 35.5} \right)\, = \,162.3\,{\text{g}}\,{\text{mo}}{{\text{l}}^{ - 1}}$.
Molar mass of ferric chloride is $162.3\,{\text{g}}\,{\text{mol}}{\,^{ - 1}}$
Since molar mass is mass in grams of one mole of an element its unit is ${\text{g}}\,{\text{mo}}{{\text{l}}^{ - 1}}$

Note:
Ferric chloride is harmful, highly corrosive and acidic. The anhydrous ferric chloride can be used as a powerful dehydrating agent. It has industrial uses like manufacture of pigments, sewage treatment and water purification. Anhydrous iron chloride is a strong Lewis acid that is used as a catalyst for organic synthesis.