How does laundry detergent work on a molecular level?
The molecule that makes up soap or detergent has a polar head
and a nonpolar tail. In chemistry, compounds that are polar like to
mix with other polar compounds and compounds that are nonpolar like
to mix with other nonpolar compounds. This is why oil and water
don't mix. Water is polar and oil is nonpolar. Oil and grease are a
nonpolar compounds. When in water the soap molecules will arrange
themselves in such a way that the nonpolar tails surround the
grease creating a spherical droplet. On the face of this sphere is
the polar heads of the soap molecule. This allows it to interact
with the polar water. This is how soap and laundry detergent are
able to remove oil and grease and wash it down the drain.