Chemistry Cat Fight

If you’ve ever seen oil and water interact, you know some
things simply don’t mix! Like cats and dogs, oil and water refuse to get along
and work together! Oil and water didn’t get into a fight, but instead they have
differences at the very smallest unit… molecules!

All things are composed of matter, from your body to your
chair. Chemistry, the study of matter, works to understand how all matter works
and interacts. All matter is composed of molecules, the tiniest particle that
matter is composed of. To understand how matter will behave, chemists must
understand how these molecules work. Atoms are the basic unit of an element,
such as oxygen or aluminum, and these atoms form together to create larger
molecules.

Let’s take a look at the molecules of oxygen and oil to
understand why they do not mix! Water molecules are polar, meaning one side of
the molecule has a positive charge while the opposite side has a negative
charge. Water’s polar charge helps the molecules to bond together; other
substances with polar molecules such as sugar, salt and ammonia will easily
bond with water! Unlike water and some of water’s closest friends, oil is
non-polar, meaning that the molecule has a uniform charge.

Due to opposing polarity of water and oil, the molecules
can’t bond together! Water molecules will attract other water molecules while
oil molecules attract other oil molecules. As these two substances stick
together, they form a visual rivalry and separate themselves. Oil will float to
the top of water; this is because water is denser than oil. Density means there
are more molecules of a substance within a given volume, making one substance
heavier than another.

If you take a bottle of oil and water and shake it, you can
get the two to mix temporarily before they separate back into themselves. This
is called emulsion, or the mixing of two liquids. To get water and oil to mix
for a longer period of time, you can use an emulsifier. An emulsifier is a
substance that has a molecule with one polar end and one non-polar end, and it
is able to attract both water (polar) and oil (non-polar). Soap is an excellent
example of an emulsifier and can be used to break down oil into water!

See water and oil molecules in action! Witness their
molecular battle by building your very own density tube today!

https://sciencemadefun.net/downloads/bottle2.pdf

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