Is CO2 a Polar or Nonpolar Substance?

At low concentrations, carbon dioxide, a colourless gas with the chemical formula CO2, is present in our environment and has no odour. We, as humans, are also a source of this gas, as we release carbon dioxide in various forms through our bodies. Many of you may be unsure whether or not the CO2 gas molecule is polar. This will be discussed, as well as its qualities and applications.

Is CO2 polar or nonpolar, then? Because of its linear symmetric form, CO2 (carbon dioxide) is a nonpolar molecule. Although the electronegativity of carbon and oxygen differs, making the C=O bond polar, the polarity of both opposite C=O bonds cancels out due to the symmetrical structure, resulting in a nonpolar molecule with zero dipole moment.

Carbon dioxide is a colourless and odourless gas with a density 60 percent higher than the dry air we breathe. It’s a gas that exists naturally in the atmosphere.

Humans, geysers, volcanoes, and a variety of chemical processes, such as the breakdown of carbonate in water and acid, are all natural sources.

Because it is soluble in water, it can be found in a variety of water bodies, including groundwater. Rivers, lakes, and other bodies of water

Apart from people, it is produced by a variety of aerobic species on the planet, which digest carbohydrates to produce carbon dioxide gas.

When it comes to the molecular makeup of the CO2 molecule, it is made up of one carbo atom and two oxygen atoms.

CO2 has a molecular mass of 44.009 gmol1. The formula is as follows:

CO2 mol mass = 1 * 12 (mol mass of carbon) + 2 * 16 (mol mass of oxygen) = 44.009 gmol1

Carbon is the core element, surrounded on both sides by two oxygen atoms. Because both oxygen atoms are opposite each other, the molecule has a linear structure.

Carbon has an electronegativity of 2.55 and oxygen has an electronegativity of 3.44. The difference in electronegativity between the two atoms is enough to provide polarity across C=O links in the CO2 molecule.

However, because to the molecule’s symmetry, or linear structure, both C=O bonds are opposite one other, and their polarity cancels out.

The CO2 molecule is a nonpolar molecule with a dipole of 0 D.

CO2 is a nonpolar molecule for a reason.

Because of the following, the CO2 molecule is polar.

The CO2 molecule’s symmetrical shape (linear) cancels out the polarity of the C=O polar bonds, resulting in a net dipole of zero.

The oxygen valence electrons are 6 and the carbon valence electrons are 4. Carbon requires four electrons to complete its octet, while oxygen only two.

As a result, two oxygen atoms and one carbon atom share two electrons, forming double bonds between them and filling their octet to stabilise them.

Both sides of the carbon atom have oxygen atoms. And because oxygen is more electronegative, it pushes the bound electron pair to its side, gaining partial negative charge, while carbon acquires partial positive charge.

The dipole across the C=O bonds is non zero and points towards oxygen; nevertheless, the equal and opposing dipoles cancel each other out, resulting in a nonpolar molecule.

Molecules that are Polar vs. Molecules that are Nonpolar

A molecule’s polarity is determined by the sort of bonding that exists between its atoms. Depending on the circumstances, covalent bonding can be polar or nonpolar.

Examine the distinctions between the properties of polar and nonpolar molecules.

Non-Polar Molecules: These molecules are electrically neutral, and the bound shared electrons in these molecules are at an equal distance from both atoms, establishing a covalent bond.

These molecules’ dipole moment is always zero.

There is no difference in electronegativity between the atoms in these compounds. It signifies that the atoms share bound electrons equally.

Hexane and CCl4 are two examples of these molecules. You can look into the reason for CCl4’s non-polarity.

Polar Molecules contain an uneven charge distribution throughout their atoms. There is a variation in electronegativity between the atoms.

The bound electron pair is drawn towards the more electronegative atom, resulting in a relative negative charge. The other atom, on the other hand, has a relative positive charge.

These compounds have a non-zero dipole moment. SO2, H2O, and other molecules are examples of these molecules. You can look into the explanation for SO2’s polarity.

Important considerations in determining a molecule’s polarity

Electronegativity: When the electronegativity of the atoms forming a covalent bond differs, the polarity of the link is guaranteed.

Higher electronegative atoms exert greater impact on the bound electron, gaining partial negative charge and becoming the negative pole of the molecule, whilst another atom becomes the positive pole.

A molecule’s polarity is proportional to the difference in electronegativity between its atoms.

The dipole moment of polar molecules is always greater than zero. It is a measurement of a molecule’s polaroid.

It’s also known as the product of atom charge and the distance between positive and negative charge centres.

Its SI unit is Debye, which is represented by the letter D.

When comparing the forms of nonpolar and polar molecules, you’ll see that nonpolar molecules have symmetric shapes, but polar molecules have asymmetric (distorted) shapes.

The charge distribution on the atoms of nonpolar molecules is uniform due to their symmetric configuration.

The form of the CO2 molecule is depicted below.

CO2’s properties

It has the appearance of a colourless gas.

This gas has a density of 1.98 kg/m3, which is 1.67 times that of dry air.

This gas has a vapour pressure of 5.73 MPa at 20 degrees Celsius.

CO2 has a melting point of 56.6 °C (69.8 °F).

The CO2 molecule has a linear geometrical shape.

CO2 has a dipole moment of 0 D.

Because it is soluble in water, it can be found in bodies of water such as groundwater, rivers, and lakes.

CO2 Applications

In our daily lives, CO2 gas is commonly used for refrigeration and cooling.

This gas is also utilised in fire extinguishers since it quickly puts out a fire.

This gas is also utilised in the casting mould industry to increase the hardness of the moulds.

CO2 gas can also be found in soft drinks, which we frequently consume.

Conclusion

One carbon atom and two oxygen atoms make up a CO2 molecule. Carbon and oxygen create a linear structure with double bonds (C=O).

Because oxygen is more electronegative than carbon, the C=O bond is polar, resulting in a non-zero dipole moment.

You should also read the article on CO2 Lewis structure, Molecular geometry, and Hybridization for more information on the geometry and lewis structure of the CO2 molecule.

However, due to CO2’s symmetrical molecular structure, the dipoles of both opposite C=O bonds cancel each other out, making it a nonpolar molecule.

So, if you have any doubts, please let us know in the comments area below. We’ll get back to you as soon as we can.

Read more: Is N2 a Nonpolar or Polar Gas?

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.

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