Why Onions Make Us Cry

Most of us know how annoying chopping a raw onion can be because it usually makes our eyes sting and tear up.

But why does this happen?

A chemist teacher in the United Kingdom created a whole bunch of interesting graphics on his blog Compound Interest that explain the chemistry behind of everyday foods.

One of the graphics, posted below, explains why slicing into an onion makes us cry. In short, an enzyme that's released when the onion is chopped breaks down compounds within the onion to form the compound that irritates the eyes and causes them to water. Read more about the specific compound produced in this process below.

Compound Interest

Head over to the Compound Interest to see more educational graphics about chemical compounds »