A Moment of Science

All Burned Up: Where Does Burnt Paper Go?

You took a stack of paper and burnt it. What happened to the papers when you lit them up?

burnt paper

Photo: Max Stanworth (Flickr)

Be careful when you burn the edges!

Have you ever burnt a stack of papers? Maybe a few exams you didn’t do so well on in that high school history class and you thought you’d avoid a load of grief from your folks by just burning the evidence?

Well, if you weren’t doused with water by a parental unit hiding in the bushes, what happened to those papers when you lit them up?

Smoke And Ash And…

Of course burning paper turns it to smoke and ashes and from our everyday experience, whether it’s burning old exams or firewood, we typically experience burning in a similar way: when we burn something it gets lighter or, in other words, it loses mass. But this is not true in general!

For example, when metals are burned, they actually gain mass!

Combustion

This is because combustion, another word for burning, is actually a chemical reaction which produces heat via a reaction between an oxidant, like oxygen, and some other substance.

For example, when paper is burned oxygen from the air combines with carbon and hydrogen in the paper turning some of it into carbon dioxide and water vapor, which waft away with carbon particulates in the smoke. This, not surprisingly, leaves the solid ash leftover lighter than the original paper.

Producing Smoke

However, burn a common metal such as steel, copper, or aluminum and the oxygen from air actually sticks to the metal forming an oxide instead of producing heavy smoke, making the whole mass heavier.

When iron, or any other metal for that matter, rusts a similar process is taking place–that is, oxygen from the air is bonding to the metal, increasing its mass.

Stay Connected

What is RSS? RSS makes it possible to subscribe to a website's updates instead of visiting it by delivering new posts to your RSS reader automatically. Choose to receive some or all of the updates from A Moment of Science:

Support for Indiana Public Media Comes From

About A Moment of Science

Search A Moment of Science