Formaldehyde is the simplest naturally occurring organic compound having its chemical formula CH2O. It exists in the gaseous state with its colorless appearance. Many of you may have a doubt regarding whether CH2O is polar or not. In this article, I will answer this question and will cover its properties and applications.
So, is CH2O polar or nonpolar? CH2O is polar in nature because of the higher electronegativity of oxygen(3.44) atom. The oxygen atom gains partial negative charge leaving behind partial positive charge on carbon and hydrogen atoms. Due to this charge imbalance, the molecule turns out to be polar.
Formaldehyde is the simplest form of the aldehyde (R-CHO) where R is the series of hydrocarbon. In the pure state, this substance is in the state of a colorless gas.
Formaldehyde is considered to be dangerous for human health due to its toxicity. It has an irritating, pungent odor.
On its condensation, this gas can be converted into many different forms having more practical uses.
The molar mass of formaldehyde is 30.026 g·mol−1. This can be calculated as below
Mol mass of CH2O = 1* 12 (Mol mass of C) + 2 * 1 (Mol mass of H) + 1 * 16 (Mol mass of O)
= 30.026 g·mol−1
If we check its chemical composition, a formaldehyde molecule consists of 1 carbon, 1 oxygen, and 2 hydrogen atoms.
The carbon is the central atom surrounded by two hydrogen atoms at one side and 1 oxygen atom at the other side.
The valence electrons of carbon are 4, hydrogen is 1 and that of oxygen is 2.
2 hydrogen forms a single covalent bond and oxygen form a double bond in order to complete its octet resulting in a stable CH2O molecule.
The electronegativity of oxygen is 3.44 and that of carbon is 2.55. Being higher electronegative, oxygen atom pulls the bonded electron pair to its side, and negative charge intensity on oxygen atom increases.
Whereas the carbon and hydrogen get a partial positive charge.
In addition to this, the oxygen is connected to carbon via a double bond, therefore the density of electron on oxygen is higher than other atoms.
Due to this imbalance of charge across the CH2O molecule, the molecule turns out to be polar.
Let us check more the fundamentals of polarity.
Polar versus Nonpolar Molecule
The molecule is bound by the forces that keep its atoms to hold with each other. The types of interatomic forces can be ionic, covalent, metallic bonds, hydrogen bonding.
The covalent bonds can be polar or nonpolar depending upon various factors.
Polar Molecules: The polar molecules are the molecules in which there exist two oppositely charged poles.
The molecules have an uneven distribution of charge across it. There is always a difference between the electronegativity of its atoms.
The more electronegative atom attracts the electrons with more influence on its side. As a result, it gets partial negative charge and other atoms get partial positive charge.
It is generally seen that the polar molecules have asymmetric shapes due to which there is an imbalance if charge across the molecule.
Few examples of polar molecules are OF2, CHCl3, etc. You can check out the reason for the polarity of CHCl3.
Nonpolar Molecules: The nonpolar molecules are those in which there is an equal distribution of charge on its atoms.
The molecules have a uniform distribution of charge across it. In most cases, the electronegativity of atoms of nonpolar molecules is equal.
The shape of nonpolar molecules is symmetric due to which the charge is equally dispersed on its atoms.
It is possible to have polar bonds within a nonpolar molecule because the polarity of such bonds gets canceled by each other due to the symmetric shape of the molecule.
Few examples of such nonpolar molecules are Cl2, CS2, etc. You can check out the reason for the non-polarity of CS2.
Why is CH2O a Polar Molecule?
The CH2O molecule consists of 1 carbon, 1 oxygen, and 2 hydrogen atoms. The carbon is the central atom surrounded by oxygen and hydrogen atoms.
The electronegativity of oxygen is 3.44 and of carbon is 2.55 and that of hydrogen is 2.2.
Being most electronegative in the CH2O molecule, Oxygen pulls the bonded electron pair to its side.
In addition to this, the oxygen is connected to carbon via a double bond due to which the intensity of the electrons also increases on the oxygen atoms.
As a result, the oxygen atom gains a partial negative charge, and carbon and hydrogen atoms gain a partial positive charge.
Formaldehyde generates two poles ie; negative and positive across its molecule and it turns out to be polar in nature.
Points to check if a molecule is polar or not
There are a few points that should be kept in mind to determine the polarity of a molecule. We will check out all of them below.
Electronegativity: The term electronegativity of an atom is its strength to attract the bonded electron pairs to its side. More the electronegativity of an atom, more closer it attracts the bonded electron pair.
If there is a difference between the electronegativity of two atoms that are covalently bonded to each other, the bond formed is said to be polar.
The polarity of a molecule is directly proportional to the difference between the electronegativity of atoms include in it.
As here, oxygen is higher electronegative than carbon and hydrogen, therefore it pulls the negative charge more towards its side and gains a partial negative charge.
Dipole Moment: The term dipole moment of a molecule is the measure of its polarity. Greater the value of the dipole moment of a molecule more is its polarity.
It is the product of the charges on atoms and differences between the centers of positive and negative charges.
It is denoted by D, with its SI unit Debye.
D = Q * R
The dipole moment of the polar molecule is always non zero whereas the dipole moment of nonpolar molecules is 0.
The dipole moment of formaldehyde is 2.330 D.
Geometrical Shape: The geometrical shape of a molecule is an important physical parameter to check the polarity of a molecule.
The polar molecules are seen to be asymmetric due to which the charges over the molecule is unevenly dispersed on its atoms.
On the other hand, the nonpolar molecules are symmetrical in shape due to which the balance of charge on all atoms remains equal.
Below is the shape of the geometrical shape of the CH2O.
Regarding its lewis structure, you must also refer to the article on the lewis structure of CH2O.
Properties of CH2O (Formaldehyde)
- Its systematic IUPAC name is Methanal.
- The molecular mass of CH2O is 30.026 g·mol−1.
- At room temperature, it exists as a colorless gas with an irritating and pungent odor.
- At a temperature of −20 °C, the density of this substance is 0.8153 g/cm3.
- The melting point of this substance is −92 °C or −134 °F and its boiling point is −19 °C or −2 °F.
- It is soluble in water with solubility value 400 g/L.
- The dipole moment of Formaldehyde is 2.330 D.
Uses of CH2O (Formaldehyde)
- This substance is used for making building material and other household products.
- It is also used in wood and furniture industries for making pressed-wood products like plywood, fiberboard, etc.
- It is also used for the manufacturing of adhesives, glues, etc.
- It is also used for making certain insulating products.
Formaldehyde consists of oxygen, carbon, and 2 hydrogen atoms. Oxygen is a higher electronegative atom and connected with carbon via a double covalent bond due to which the intensity of the negative charge increases on the oxygen atom.
Due to the difference between the electronegativity of oxygen, carbon, and hydrogen atoms, the molecule has an uneven distribution of charge and has the value of dipole moment as 2.330 D making it a polar molecule.
If you guys have any queries about the polarity of formaldehyde, you can ask them in below comment section and I will reach out to you soon.