PCl5 is the formula for the chemical compound phosphorus pentachloride. It exists at room temperature as colourless crystals. It is a widely used chlorinating agent in a variety of chemical reactions. It is susceptible to water and dampness. Many pupils may have questions about whether or not PCl5 is polar. In this post, I will provide an answer to this question and discuss its surrounding topics.
Consequently, is PCl5 polar or nonpolar? PCl5 is nonpolar due to its symmetrical geometrical structure, which cancels out the polarity of the P-Cl bonds. Consequently, PCl5 has zero net dipole moment.
PCl5 appears as a colourless crystal at ambient temperature. It is a prevalent chlorinating agent.
In 1808, it was initially discovered by the renowned English chemist Humphry Davy.
The chemical compound PCl5 has an offensive odour. PCl5’s IUPAC name is phosphorus pentachloride.
Due to the presence of HCl, samples used commercially in laboratories can be yellowish.
PCl5 is composed of five chlorine atoms and one phosphorus atom held together by covalent bonds.
The valence electrons of Phosphorus are five, while those of Chlorine are seven.
The atom of chlorine requires one electron to complete its octet. Five chlorine atoms share one electron from a phosphorus atom, leaving no lone pair.
With this electrical arrangement, PCl5 molecules are rendered neutral.
Phosphorus has an electronegativity of 2.19, while chlorine’s is 3.16. Polarity in the P-Cl bond is caused by the difference in electronegativity between phosphorus and chlorine.
Electronegativity of an atom refers to its ability to attract bound electron pairs. More electronegative atoms attract the pair of linked electrons more strongly.
Similarly, the Chlorine atom draws the bound electron closer to it in the P-Cl bond. Thus, the chlorine atom acquires a partial negative charge and the phosphorus atom acquires a partial positive charge.
However, due to the symmetrical geometrical structure of PCl5, i.e., trigonal bipyramidal, the polarity of the P-Cl bond is cancelled out, making PCl5 a polar molecule overall.
Polar and nonpolar molecules are defined.
The bonds that hold the molecules together can be ionic, metallic covalent, or hydrogen bonding. Covalent bonds may be polar or nonpolar, depending on variables such as electronegativity, geometrical form, and dipole moment.
Polar Molecules: These molecules have a net dipole moment that is greater than zero. The covalent bond between two atoms is considered to be polar if their charge distributions are uneven.
These two atoms have uneven electronegativity and a nonzero dipole moment as a result.
Such chemicals include H2O, OF2, and others. You can investigate the cause of water’s polarity.
Nonpolar Molecules: These are molecules with a dipole moment of zero. If the two atoms covalently bound share an equal fraction of charge, the resulting bond is nonpolar.
In addition to having the same electronegativity, these atoms produce a dipole moment of zero.
These molecules include CO2, O2, PCl5, etc. Examine the reason behind CCl4’s non-polarity.
It may be feasible for nonpolar molecules to include polar bonds. Due to the symmetrical geometrical structure of the molecule, the polarity of such bonds is cancelled with one another.
What makes PCl5 a nonpolar molecule?
Because of its symmetrical form, phosphorus pentachloride is nonpolar. It has the geometric shape of a trigonal bipyramid.
The three P-Cl bonds are in one plane, locked in place by the corners of an equilateral triangle, whereas the remaining two bonds lie axially to the plane of the three bonds.
The polarity of the P-Cl bond is determined by the 0.97D electronegativity difference between the chlorine and phosphorus atoms in the PCl5 molecule.
Phosphorus has a stronger electronegative atom than chlorine. As a result, the chlorine atom shares a greater amount of its charge, it attracts the bonded pair a little bit more strongly, and it acquires a fraction of a negative charge.
Phosphorus, on the other hand, acquires a partial positive charge.
P-CL link assures a nonzero dipole moment, but due to symmetrical geometries, the polarity of P-Cl bonds is cancelled out by other P-Cl bonds.
Due to its symmetrical form, it is essential to recognise that although PCl5 has polar bonds, it is nonpolar in nature.
PCl5’s Geometrical Construction
Phosphorus is bonded to five chlorine atoms, all of which are covalent in nature.
The three bonds lie in a single plane such that three P-Cl bonds form a 120-degree angle with one another and are located at the corners of a triangle with equal sides.
In addition, the remaining two P-Cl bonds are located at the two extremities of an axis that passes across the plane of the three P-Cl bonds.
The two axial bonds are perpendicular to the plane of the remaining three P-Cl bonds.
The bond length of the two axial P-CL bonds is 240 pm, but the bond length of the P-CL bonds in another plane is 202 pm.
PCl5 has a trigonal bipyramidal form.
The graphic above depicts the geometry of the phosphorus pentachloride molecule.
Variables influencing the polarity of a molecule
Electronegativity: An atom’s electronegativity influences the strength of its ability to attract bound electrons. If two atoms forming a covalent connection have different electronegativity, the bond is said to be polar.
Polarity is directly proportional to the difference in electronegativity between two molecules.
Dipole moment is the measurement of a molecule’s polarity. Greater a molecule’s dipole moment, the greater its polarity.
Consequently, a molecule’s polarity is directly proportional to its dipole moment. The dipole moment of a molecule is the product of the molecule’s charge and bond length.
Molecular structures that are symmetrical in nature are typically nonpolar. Even though these molecules have a polar link, their overall nature is nonpolar.
Due to the symmetry of the structure, the polarity of such a molecule is cancelled out.
Characteristics of PCl5
Phosphorus pentachloride is a solid crystal with an offensive odour.
This molecule has a molecular mass of 208.2 g/mol.
A high concentration of PCl5 can result in severe health concerns.
PCl5 has a density of 2.1 g/cm3.
It decomposes easily in water to produce phosphoric acid.
This chemical compound has a melting point of 160,5 °C or 320.9 °F.
PCl5 has a boiling point of approximately 166.8 °C or 332.2 °F.
At 80 degrees Celsius, PCl5 has a vapour pressure of 1.11 kPa.
It is not naturally flammable.
Utilization of PCl5
It is frequently employed as a chlorinating agent in the production of many industrial products.
Additionally, it is utilised as a dehydrating agent.
It is utilised extensively as an intermediate molecule in the production of insecticides and water treatment products.
It is utilised to enhance the grain structure of metals.
It also contributes to the production of lithium hexafluorophosphate, an electrolyte used in lithium-ion batteries.
Conclusion
Because of its geometrical structure, phosphorus pentachloride is nonpolar. It is symmetrical, or trigonal bipyramidal. Because of this, the polarity of P-CL bonds is cancelled out.
Therefore, it is feasible for a molecule to be nonpolar despite the presence of polar links. This is due to the symmetrical geometrical structure of PCl5, for example.
These characteristics make PCl5 a nonpolar molecule.
Therefore, if you have any questions regarding the polarity of PCl5, feel free to post them in the comments area. We will contact you as quickly as possible.
Read more: Polarity, NH2 Lewis Structure, Molecular Geometry, and Hybridization
