Methanol is the simplest type of alcohol having a methyl group attached to the hydroxyl group(-OH). Methanol is colorless and has a similar odor like that of ethanol. It is light and flammable in nature. Ethanol and Methanol have one major difference that methanol is toxic in nature. Many science students may have a doubt regarding whether methanol is polar or nonpolar. In this article, I will answer this question and cover surrounding topics too.
So, is methanol polar or nonpolar? Methanol is polar in nature because the OH group dominates and makes it polar because oxygen is more electronegative than carbon and hydrogen atoms. As a result, oxygen gains a partial negative charge on it, and carbon and hydrogen gain a positive charge.
Methanol is the simplest alcohol that contains only 1 carbon atom connected with three hydrogen bonds and one hydroxyl group. This is also known as methyl alcohol. Methanol is its IUPAC name.
Its chemical formula is CH3OH containing one carbon atom, one oxygen, and four hydrogen atoms. The molecular mass of methanol is 32.04 g per mol.
It is calculated as
1* (mol mass of C) + 4*(mol mass of H) + mol mass of O
12+1×4+16 = 32 grams.
Methanol does not have texture, it is a colorless liquid and smells like ethanol. Methanol has low toxicity towards human beings but can be dangerous if consumed in volume.
The denatured alcohol is because of methanol added with ethanol and also It is very difficult to distinguish between ethanol and methanol because of similar odor and appearance.
The molecule of methanol has covalent bonds within it. The hydroxyl group is connected with carbon with one of its four bonds.
The shape of the molecule of methanol (CH3OH) is asymmetrical in shape. The symmetricity of a molecule is an important factor in determining its polarity.
Apart from geometrical symmetry, electronegativity and dipole moment are also important factors that determine the polarity of a molecule.
What are polar and nonpolar molecules?
When two or more atoms form a chemical bond to form a molecule, the exchange of electrons occurs between atoms. In some molecules, the charge distribution among the atoms in a chemical bond is equal. Whereas some molecules have unequal charge distribution among the atoms.
The chemical compounds have their molecules held by the bonds and the types of chemical bonds are ionic, covalent, metallic, and hydrogen. These bonds held the atoms together. Out of these, ionic and covalent are commonly used and strongest bonds.
The ionic bond is formed between the atoms that are oppositely charged. The two oppositely charged atoms get attracted and stabilize each other. Example of ionic molecules is NaCl, KCl, etc
The covalent bond is formed among the atoms when there the atoms share electrons of each other to complete their octet. Examples of the covalently bonded molecule are H2, CO2, etc.
The covalent bonds can be polar or nonpolar. Two atoms having a covalent bond form polar molecules if the charge distribution on both atoms in unequal. In such molecules, there is a difference in the electronegativity of both atoms.
More electronegative atom attracts the shared electron pair slightly towards itself and gains a partial negative charge whereas the other atom gets a partial positive charge.
Whereas in the case of nonpolar molecules, the charge distribution on both atoms forming a covalent bond is equal. It means that the electron pair is equally shared by both atoms.
Why methanol is polar?
In the case of Methanol, the hydroxyl group (-OH) is attached to a carbon that dominates the molecule and the oxygen is more electronegative than hydrogen and carbon due to which oxygen gains a partial negative charge and carbon and hydrogen gain partial positive charge.
As a result, the O-H and C-O bonds become polar and both bonds have some dipole moment value.
Thus, the molecule of methanol results in a net value of dipole moment.
More the difference in electronegativity of atoms forming a molecule, greater is the polarity of that molecule. The polarity of a molecule is directly proportional to the difference between the electronegativity of atoms.
Similarly, the polarity of a molecule is directly proportional to the dipole moment.
The shape of methanol is asymmetric which is also an important factor for determining the polarity of a molecule.
These factors are discussed briefly below.
Factors affecting polarity of a compound
Geometrical shape: The molecules that have symmetrical geometrical shapes are nonpolar in nature because in such cases if there are any polar bonds present within the molecule, it gets canceled by each other making the complete molecule a nonpolar.
Whereas the molecules that have asymmetric shape and have polar bonds within it results in a net dipole moment and makes the molecule a polar.
Electronegativity: The electronegativity of an atom is the measure of the strength with which an atom can attract the bonding electrons towards it.
In a molecule of two atoms, the more electronegative atom attracts the bonding electrons slightly towards itself and gains partial negative charge whereas the other atom gains a partial positive charge
Dipole moment: The dipole moment is the measure of the polarity of a molecule Dipole moment is also directly proportional to the polarity of a molecule. More the value of dipole moment, greater is the polarity of the molecule.
Mathematically, it is the product of the charge and the distance between the atoms.
It can be calculated as the formula given
D = dipole moment of the molecule
Q = charge
R = distance between atoms(bond length)
The dipole moment of methanol (CH3OH) molecule is calculated 1.69 D.
Geometrical Structure of Methanol
The molecule of methanol has two geometrical centers (carbon and oxygen).
The carbon atom is the central atom that has no lone pair and makes four sigma bonds with three hydrogen atoms and one with a hydroxyl group.
The shape of the methanol molecule is tetrahedral if carbon is considered as the central atom.
Oxygen forms two sigma bonds with two lone pairs on it and forms a bent shape. The bond angle is around 104.5 degrees.
Below is the look of the molecular structure of methanol (CH3OH) molecule.
Properties of Methanol
- Methanol is a colorless liquid and poisonous in nature.
- It is light and simplest alcohol and flammable.
- The boiling point of methanol is 64.96 °C or148.93 °F and its melting point is −97.6 °C or −143.7 °F.
- It is produced by the natural anaerobic metabolism of bacteria.
- Its smell is similar to that of ethanol.
Uses of Methanol
- Methanol is a type of non-drinking alcohol that is used to create fuel, antifreeze, solvent.
- It is used in the manufacturing of acetic acid and formaldehyde.
- It is used in sewage treatment plants.
- The mixture of methanol and water has great use in the high performance of the engine to increase power.
- It also its major use in the preparation of aromatic compounds, hydrocarbons.
- It is used for making methylamines and methyl esters.
Methanol is polar in nature due to the unequal charge distribution of the atoms and its asymmetric molecular geometry.
The oxygen is more electronegative than hydrogen and carbon gain partial negative charge and hydrogen and carbon gets a partial positive charge.
As a result, the polarity comes within the C-O and O-H bond. And the molecule results in a net dipole moment.
I hope you guys understand the reason why is methanol a polar compound. If you have any questions, you can ask them in the comment section. We will reach out to you as soon as possible.