Here's a Question!

Announcer: Frostbite Theater presents... Cold Cuts! No baloney!

Joanna and Steve: Just science!

Joanna: Hi! I'm Joanna!

Steve: And I'm Steve!

Joanna: Here's a question for you...

Steve: Steel wool is placed in a beaker.

Joanna: The beaker is placed on a scale and the total mass is measured.

Steve: Then, the steel wool is then set on fire.

Joanna: Yaaaaeee!

Once the fire burns itself out, the total mass is measured again.

Steve: How will the masses compare?

Joanna: Will the mass be greater before the fire?

Steve: Will the mass be greater after the fire?

Joanna: Will the masses be the same?

Steve: Or, is this a trick question because metals don't burn?

Joanna: Pause the video now if you'd like to think it over before we show you what happens.

Steel wool is mostly iron. When iron burns, it reacts with oxygen in the air, forming iron oxide.

Steve: Iron plus oxygen is more massive than iron alone. So, what's left of the steel wool is more massive after it's been burnt.

Joanna: Thanks for watching. I hope you'll join us again soon for another question!