Dichlorodifluoromethane, sometimes known as Freon-12 or R-12, is an odourless, colourless gas with a mild odour resembling ether.
It is classified as a chlorofluorocarbon (CFC) chemical. It is a derivative of an alkane. Alkanes are saturated hydrocarbons that only contain carbon and hydrogen. All hydrogens are replaced in CFCs.
This page discusses the polarity of CF2Cl2 and the factors that influence it.
Consequently, is CF2Cl2 polar or non-polar? The asymmetric structure of CF2Cl2 makes it a polar molecule. C-F and C-Cl bonds are polar due to their dissimilar electronegativity (C is the least electronegative). Due to asymmetry, the dipole moment vectors of bonds inside molecules do not cancel each other out, and the complex as a whole is polar.
The mass per mole of CF2Cl2 is 120.91 grammes. The melting point is -158°C and the boiling point is -30°C. It is conveyed as a liquefied gas under pressure.
It is soluble in organic solvents such as ethanol and ether. It is an inflammable material. Due to the strong stability of C-F bonds, it is chemically inactive.
Using the following procedure, freon 12 is produced on a laboratory scale.
CCl4 plus HF plus SbF3Cl2 (catalyst) produces CFCl3 plus CF2Cl2 plus HCl.
R-12 is utilised frequently in cleaning solutions, refrigerants, and degreasers. It is also employed as a fire retardant in submarines and aircraft.
The molecule’s point group is C2v. This suggests that a 180° rotation of the molecule yields an identical structure and that the molecule contains two planes of symmetry.
In this combination, F and Cl have an oxidation state of -1, while C has an oxidation state of +4. As it has a deleterious impact on the ozone layer, the Montreal Protocol prohibits the manufacturing of CF2Cl2 in many nations. It is categorised as a greenhouse gas.
Let get started analysing it in more detail.
Why is CF2Cl2 a polar compound?
There are two types of bonds in CF2Cl2: C-Cl and C-F.
Cl and F are electronegatively more negative than C. C, Cl, and F have electronegativity values of 2.55, 3.16, and 3.98, respectively.
This distinction results in polar bonding. Dipole moment vectors are directed from C to Cl/F in both instances.
C has a partial positive charge, while F and Cl have partial negative charges. Polar bonds do not guarantee a polar molecule.
It is tetrahedral in structure. The compound should have been symmetrical, but due to various side atoms, it is not.
If all the side atoms were identical, it would have been symmetrical.
Due to the difference in magnitude of dipole moment between the two types of bonds, the net dipole moment is non-zero and the compound is polar.
Structure Lewis of CF2Cl2
Lewis structure illustrates the most fundamental atomic arrangement in a molecule. The octet rule is the foundation of the Lewis Structure.
We select the atom with the lowest electronegative charge as the centre atom.
C has four valence electrons, while Cl and F each have seven.
The arrangement of these valence electrons surrounding atoms completes the octet of each atom.
C shares one valence electron with each side atom, as do each of the side atoms.
Why is CF2Cl2 a tetrahedral molecule?
VSEPR theory permits the determination of the form of any covalent compound.
According to the VSEPR hypothesis, electrons in the valence shells of atoms in a molecule reject each other and arrange themselves to minimise this repulsion.
This stable configuration of electrons is known as geometry.
Procedure to determine the geometry of CF2Cl2
Count the number of valence electrons on the centre atom, which in this case is C. 1s2 2s2 2p2 is the electrical configuration of the element C.
Valence shell contains four electrons.
For each side atom, one contribution is added to the central atom.
CF2Cl2 contains four side atoms, resulting in four contributions to the centre atom and a total of eight.
By dividing 8 by 2, we determine that there are four electron pairs.
This table estimates the structure and geometry of a molecule based on the total number of electron pairs and the general formula.
Thus, CF2Cl2 has a tetrahedral form.
What exactly is Polarity?
Polarity is one of the key physical properties of a chemical.
Atoms acquire partial charges when the shared electrons are not equally distributed between them.
The more electronegative atom attracts the shared pair of electrons to itself and acquires a partial negative charge.
The less electronegative atom attracts the shared pair of electrons less strongly and acquires a partial positive charge.
This separation of opposite charges produces a dipole, and the resulting bonds are referred to as polar.
Polar and Non-Polar Compounds Differ
|Basis||Polar Compounds||Non-polar compounds|
|Dipole moment||Non zero||Zero|
|Type of bonds||Polar (at least one)||Polar (symmetry leads to non-polarity) or non-polar|
|Boiling and melting point||High||Low|
|Electronegativity Difference||High (>0.4)||can be high or low.|
|Electron cloud||Distorted||Not distorted|
|Electricity Conduction||Conducts electricity in solution.||It does not conduct electricity.|
|Example||H2O, NH3, CF2Cl2 etc.||CO2,H2,N2 etc.|
Aspects Influencing the Polarity of CF2Cl2
Numerous factors can trigger the formation of uneven partial charges within a molecule. Important causes are
Moment of dipole – It is a vector quantity that is the product of the magnitude of charges and their separation.
It is frequently referred to as the polarity indicator. Dipole moments exist only when the charges split.
Debye is the SI unit for dipole moment. It is found in both ionic and covalent molecules.
The calculation formula for dipole moment is
µ (Cm) = Q (C) * r (m)
where represents dipole moment
Q represents the magnitude of charges, while r represents the distance between two charges.
The figure below depicts the orientation of dipoles within the CF2Cl2 molecule.
The difference in electronegativity – Typically, no two elements possess the same electronegativity.
There is always a difference in electronegativity between any two atoms, regardless of how minute.
This difference in electronegativity permits one of the atoms to acquire a negative charge by attracting the pair of shared electrons toward itself.
Similarly, the other atom acquires a partial positive charge to preserve the molecule’s net charge. Thus, a dipole is formed as a result of varying electronegativity.
3 Geometry and Symmetry — If the bonds are non-polar or diatomic, geometry has no effect. Since diatomic bonds are always linear, geometry is irrelevant.
The geometry of polar bonding is a key aspect.
If the geometry of a compound is symmetrical, such as linear, and all the side atoms are identical, then all the dipole moment vectors point in opposing directions and cancel out.
This renders the substance non-polar. If the geometry is not symmetrical, such as in a bent structure, dipole moment vectors do not cancel.
Different side atoms can also cause asymmetry; in the case of CF2Cl2, the amplitude of the dipole moment would vary.
4 Charge Separation – The distance between the two partial charges also influences the polarity’s magnitude.
Why is CF2Cl2 a Covalent Compound?
Covalent substances create bonds through the exchange of electrons between atoms. To facilitate sharing, the difference in electronegativity between the atoms should be smaller than 1.5.
If there are more, sharing will not be possible since one atom will attract the shared pair more strongly.
The difference in electronegativity between carbon and fluorine is 1.43 (3.98-2.55), while it is 0.61 between carbon and chlorine (3.16-2.55).
Non-metals make covalent bonds with C, Cl, and F, which are also non-metals. No substance is exclusively covalent or ionic.
Every covalent substance contains ionic properties, and every ionic compound contains covalent properties.
Using Fajan’s rule, the relative covalent character can be compared.
The following factors favour the covalent nature of a compound:
• The diminutive size of cation
• The substantial size of anion
• Additional fee on the cation
Why is CF2Cl2 Prohibited?
In the stratospheric portion of the atmosphere, the ozone layer absorbs the harmful solar radiation.
When CF2Cl2 reaches this zone, UV rays decompose it into Cl-atoms, which then decompose ozone into molecular oxygen and free O-atoms.
Therefore, the ozone layer is diminished.
The Montreal Protocol prohibits ozone-depleting compounds. In accordance with this treaty, the manufacture of CF2Cl2 is prohibited in various nations.
Applications of CF2Cl2
The refrigerant in air conditioners and freezers.
Submarines and aircraft use fire retardants.
Aerosol propellants such as body spray and hairspray, etc.
Household cleaning supplies
building and construction materials
CF2Cl2 is a polar substance.
Due to the disparity in electronegativity between C and F/Cl, all four bonds are polar. Since F is more electronegative than Cl, the polarity of C-F bonds is greater than that of C-Cl bonds.
Due to the tetrahedral structure, all bond moment vectors point in distinct directions; nonetheless, they do not cancel out since the amplitude of the dipole moment is not identical.
It is polar because the net dipole moment of the compound is not zero.
As the difference in electronegativity between the elements in the molecule is less than 1.5, this substance is covalent.
Read more: NH4+: Polar or Nonpolar?