Dichloromethane is a polar solvent.
This means that it has a dipole moment, which is a measure of how strongly its molecules are attracted to one another.
In other words, polar solvents have a positive end and a negative end, and the positive end of one molecule will be attracted to the negative end of another molecule.
Is CH2Cl2 Polar or Non-Polar? (Explained)
What is Dichloromethane?
Dichloromethane is a colorless, flammable liquid with a sweet-smelling odor.
It is used as a solvent in various industries, including paint and varnish manufacturing, textiles, and printing.
Dichloromethane can also be used as a refrigerant and an aerosol spray propellant.
People may be exposed to dichloromethane in air, water, food, or soil.
If it is released into the air, dichloromethane can form small droplets that are carried by wind and dispersed over long distances.
People who live near areas where dichloromethane has been used or produced have a greater chance of being exposed to this chemical.
Dichloromethane enters the body either through the lungs (breathing) or through contact with the eyes, skin, or stomach contents if it is swallowed.
Once inside the body, most of it leaves within two days in urine and breath as carbon monoxide and carbon dioxide.
Some dichloromethane leaves the body in sweat.
Dichloromethane is broken down into carbon monoxide by an enzyme called cytochrome P-450 in the liver.
Products that use dichloromethane include paint removers, adhesives, spray paints, model airplane glue, rubber cement, typewriter correction fluid, felt tip marker fluid, nail polish remover, wood stains and thinners, petroleum additives or thinners, paint strippers, oven cleaners (liquid types), water treatment chemicals, automotive degreasers (motorcycle), brake cleaners, dry-cleaning solvents, and other industrial uses.
People exposed to small amounts of dichloromethane by breathing it, touching it, or eating foods that contain it might have some of the following symptoms within minutes:
- Nausea or vomiting
- Lightheadedness or dizziness
- Rapid heart rate
People who have swallowed dichloromethane can also have these same symptoms, plus increased salivation or sweating.
Eye contact with dichloromethane can cause severe eye irritation.
Continued skin contact with high concentrations of dichloromethane may result in pain, redness, swelling, numbness, and blisters.
What Does It Mean When a Substance Is Polar or Non-Polar?
A polar molecule is one where the electrons are not evenly distributed around the atoms.
This uneven distribution creates a positive and negative end to the molecule.
A non-polar molecule has electrons that are evenly distributed around the atoms and does not have a positive or negative end.
Polar molecules are attracted to other polar molecules, while non-polar molecules are not attracted to either polarity.
This is why water (a polar molecule) is drawn to oil (a non-polar molecule), because the water molecules are drawn to the oil’s non-polarity.
However, this attractive force is not strong enough to break through the larger non-polar molecule to get to the oil.
Polar molecules are more likely to dissolve in polar solvents, while non-polar molecules will dissolve in a non-polar solvent.
For example, salt (sodium chloride) does not dissolve well in water since water is a polar molecule and sodium chloride is a non-polar molecule.
However, salt can be broken down into its ions (molecules that have lost or gained electrons) by the addition of an acid which breaks apart the ionic bonds.
The negative charge on the Cl picks up spare electrons from other ions causing them to become negatively charged as well.
This allows the ions to travel through the water because they are no longer bonded to one another.
Polar molecules are more soluble in polar solvents and non-polar molecules are more soluble in non-polar solvents.
Why is Dichloromethane Polar?
Dichloromethane is polar because it contains a polar covalent bond which means that one atom of hydrogen bonds with an atom of chlorine from the other molecule.
In order for this process to happen, the atoms in both molecules have to be different, giving them a net charge between them.
For example, if both molecules contain equal numbers of protons and electrons, then they will not join together and there will be no polarizing effect on either molecule.
This occurs because when two identical atoms are next to each other on separate molecules, their electron clouds overlap and cancel each other out (since electrons come in pairs), meaning they can’t form an electric or magnetic field, like poles of a magnet attracting or repelling each other.
Therefore, it is the difference in atom charges that is important for determining polarity.
Dichloromethane has a partial positive charge on the hydrogen atom and a partial negative charge on the chlorine atom, which is why it’s polar.
This is because when two molecules come together, the partially positive hydrogen will be attracted to the partially negative part of another molecule while at the same time repelled by its own partly negative side.
This gives it what we would call polarity.
Why Are Dichloromethane’s Sigma Bonds Polar?
Another reason why dichloromethane is polar is because of its sigma bonds.
A sigma bond is formed when the orbitals of two bonded atoms overlap one another with their electron density being equally shared between both nuclei.
They are also known as σ-bonds or sigma bonds for short.
Like in any molecule, it doesn’t matter which side you start counting from, the same number will always be found on either side of a double bond joining two carbon atoms.
So, this means that there are three sigma bonds pointing towards each other at 120-degree angles between them and thus these are said to be trigonal planar.
This formation results in dichloromethane having a flat, non-polar shape.
Furthermore, sigma bonds are also partly electrostatic and so they can be attracted to the partially negative part of another molecule, but only if it’s polarized.
And this is why we have polar C-Cl bonds as well as polar C-H bonds.
In conclusion, dichloromethane has three sigma-bonds all pointing towards each other which are arranged in a trigonal planar formation.
This causes the molecule to have a flat, non-polar shape.
The sigma bond is an attraction between two atoms where electrons are shared equally between both nuclei.
Sigma bonds occupy space, meaning that their electron orbitals overlap one another, which causes the bonding between atoms.
This makes it polar because now, whenever dichloromethane is in contact with HCl, its molecules will be attracted to each other via electrostatic forces due to their polar nature.
When these dipoles are close to each other they have an overall positive charge on one side and negative on the other, giving them opposite poles.
These poles are either attracted together or repelled apart depending if they have opposite charges (positive and negative) or similar charges (both positive or both negative).
Dichloromethane is polar because it has a high electron affinity and low ionization energy.
This means that the molecule is very reactive and can easily donate electrons to other molecules.
Dichloromethane’s polarity makes it an excellent solvent for dissolving nonpolar substances, such as hydrocarbons.
It also has a high boiling point, making it an ideal choice for industrial processes that require heat.
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