Calcium chloride (CaCl2) is a member of the alkaline earth metal halides (MX2), where M is an alkaline earth metal. It’s an odourless inorganic chemical having a white tint.
Calcium chloride is a crystalline substance that dissolves quickly in water. Because it is hygroscopic in nature, it is used in desiccators to dry chemicals.
Anhydrous calcium chloride has an extremely high melting and boiling point. Hexahydrate calcium chloride, on the other hand, has a melting point of only 29.9 °C. Its anhydrous form has a molecular weight of 111 g/mol.
CaCl2 (H2O)n, where n = 0, 1, 2, 4, and 6, is the most common hydrated form of calcium chloride. The interaction of calcium hydroxide with hydrogen chloride produces calcium chloride.
Ca(OH)2 + 2HCl —-> CaCl2 + 2H2O
The Solvay procedure, i.e. CaCO3 + 2NaCl → CaCl2 + Na2CO3, can also be used to make calcium chloride from limestone.
Calcium chloride dissolves in water to create free calcium ions, which are the aqua complex of calcium ion and chloride ion.
Is CaCl2 Ionic or Covalent?
CaCl2, referred to as calcium chloride, is a member of alkaline earth metal halides i.e., MX2, where, M is an alkaline earth metal. It is an inorganic compound of white color without any odor.
Calcium chloride is crystalline in nature and can be easily dissolved in water. It is hygroscopic in nature and hence, used in the desiccators for drying chemicals.
The melting and boiling point of anhydrous calcium chloride is very high. However, the melting point of hexahydrate calcium chloride is only 29.9 °C. The molecular weight of its anhydrous form is 111 g/mol.
Generally, calcium chloride is found in the hydrated form i.e., CaCl2 (H2O)n, where n = 0, 1, 2, 4, and 6. Calcium chloride is prepared by reaction of calcium hydroxide with hydrogen chloride.
Ca(OH)2 + 2HCl —-> CaCl2 + 2H2O
Calcium chloride can also be produced from limestone by the Solvay process i.e. CaCO3 + 2NaCl → CaCl2 + Na2CO3
Calcium chloride produces free calcium ions i.e., the aqua complex of calcium ion and chloride ion by dissolving themselves in water as follows
CaCl2 + 6H2O —–> [Ca(H2O)6]2+ + 2Cl
Because this reaction causes a significant increase in temperature (exothermic reaction), calcium chloride dissolution in water has a high enthalpy of solvation.
Is CaCl2 an ionic or a covalent salt? Because the electronegativity difference between the calcium and chlorine atoms is larger than 2.0, CaCl2 is an ionic molecule.
The calcium atom donates its two electrons to form a cation in calcium chloride, whereas each chlorine atom gains one electron from Calcium and becomes a negative charge.
The electrostatic force of attraction now attracts the calcium cation and the chlorine anions, resulting in the development of an ionic bond between these two atoms.
Let us begin by delving into the ionic composition of calcium chloride.
Let’s start with the fundamentals of chemical bonds, namely, ionic and covalent bonds.
The chemical bond is an attraction between atoms in a molecule that holds them together in their chemical structure.
When an atom creates a chemical bond, it tends to take the noble gas configuration that is closest to it.
A chemical bond is created when electrons are transferred or shared between the atoms of a molecule.
Only the atom’s valence electrons, or electrons from the outermost shell, participate in the chemical bond.
Chemical bonds are classified into two sorts based on how they are formed.
The Covalent Bond is a type of chemical bond.
The Covalent Bond is a type of chemical bond.
When electron pairs are shared between atoms in a molecule, a covalent bond is formed. However, depending on the electronegativity of the individual atoms of the molecules, this sharing may be equal or unequal.
As a result, a covalent bond can be either polar or nonpolar.
The atom’s ionisation energy is so high in covalent bonding that it can’t transfer its electron or electron pair.
The chemical bond between metal and nonmetal is known as the ionic bond.
Metals have a low ionisation energy, making it easy to transmit an electron to another atom. Because of their high electron gain enthalpy or electron affinity, nonmetals readily take these electrons.
As a result, an ionic bond is formed when electrons are transferred from one atom to another or from a metal to a nonmetal.
The electrostatic force of attraction between cations and anion will develop when cations and anion form.
The Formation of Ionic Bonds in Calcium Chloride
The Born Haber cycle helps explain how calcium chloride is formed.
Let’s take a closer look at how calcium chloride is formed.
One calcium atom and two chlorine atoms make up the calcium chloride chemical. The calcium atom, as we know, belongs to group 2 of the current periodic table, making it a metal.
The chlorine atom, on the other hand, is a nonmetal and belongs to group 17 of the contemporary periodic table.
Because metals have a low ionisation energy (I.E. ), the calcium atom will easily lose its electron. It is a two-phase process, with each step resulting in the loss of one electron.
Because calcium is a white crystalline solid, the first step would be to convert solid calcium to a gaseous calcium atom by using sublimation energy (Hsub), as metals can only contribute electrons in gaseous form.
Ca (s) + ΔHsub → Ca (g)
Ca (g) + (I.E.)1 → Ca+(g) + e-
Ca+(g) + (I.E.)2 → Ca2+ (g) + e
In most cases, the second ionisation energy is bigger than the first. However, this is not the case for the calcium atom, which is found in alkaline earth metals.
Let’s take a look at what’s causing this uproar.
The electronic configuration of the calcium atom in its ground state is [Ar] 4s2. Because the 4s subshell is a filled subshell, we must provide a substantial amount of energy to extract an electron from it.
The electrical configuration of the unipositive calcium ion changes to [Ar] 4s1 after an electron is removed.
It is now possible to remove an electron with a little amount of energy by achieving a stable noble has configuration, such as the Argon atom.
As a result, calcium’s second ionisation energy is lower than its first ionisation energy.
Because the chlorine atom is a nonmetal, it has a higher tendency to gain electrons than the calcium atom due to its higher electron affinity (E.A.). As a result, the electrons given by the calcium atom will be accepted by the chlorine atom.
Cl2 is the diatomic version of the chlorine atom. As a result, the first process would be the dissociation of chlorine elements into chlorine atoms, followed by electron acceptance.
½ Cl2 (g) + ΔHdiss → Cl (g)
Cl (g) + e- → Cl-(g) + E.A.
One calcium ion will now interact with two chlorine ions, forming an ionic link between them while releasing energy. The value of this energy, known as Lattice Energy (U), is determined by the strength of the ionic bond.
Ca2+ (g) + 2Cl-(g) → CaCl2 (s) + U
Calcium chloride has a lattice energy (U) of -2195 kJ/mol.
We know calcium chloride is an ionic chemical because of how we discovered it.
The difference between an ionic and a covalent bond
The electronegativity difference between the atoms can be used to distinguish between ionic and covalent connections.
If the electronegativity difference of a chemical bond is larger than 2.0 on the Pauling scale, it is an ionic bond; if the electronegativity difference is less than 2.0, it is a covalent link.
Calcium chloride is an ionic compound in what way?
The calcium chloride compound is an example of this (CaCl2),
According to the Pauling Scale,
The electronegativity of the calcium atom is equal to 1.0.
The chlorine atom has an electronegativity of 3.16.
The Ca-Cl bond has an electronegativity difference of 2.16.
The Ca-Cl bond in the calcium chloride molecule has an electronegativity difference of 2.16 on the Pauling scale, which is more than 2.0 and verifies the ionic nature of the Ca-Cl bond.
Calcium chloride is therefore an ionic substance.
Because of its ionic structure, calcium chloride is very soluble in water.
Hexahydrate calcium chloride crystallises in a trigonal form, whereas anhydrous calcium chloride crystallises in an orthorhombic and tetragonal structure.
Calcium Chloride’s Applications
Calcium chloride in water lowers the freezing point of water, preventing ice formation and making it suitable for de-icing.
Due to its hygroscopic nature, a highly concentrated solution of calcium chloride on the road prevents the production of dust and forms a liquid layer on the road’s surface.
The ionic nature of calcium chloride has been described here.
In conclusion, calcium chloride is an ionic molecule because the Ca-Cl bond in calcium chloride has a large electronegativity difference of more than 2.0. The calcium atom loses two electrons to form a positive calcium ion, while the chlorine atom accepts one electron to generate a negative chlorine ion.
The electrostatic force of attraction attracts the calcium ion and the chlorine ion, and an ionic bond is formed between them by releasing energy in the form of Lattice energy.
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