Conservation of Mass

Balancing Equations PhET

Balancing Chemical Equations

Even though food looks very different after you cook it, the atoms haven't disappeared—they have been rearranged into new substances.

When a car burns gasoline, the fuel doesn't simply disappear. Its atoms combine with oxygen and form new substances.

The food you eat doesn't disappear when your body uses it. Your body rearranges those atoms into new substances and releases energy.

Understanding that matter can be rearranged but not simply disappear helps scientists find ways to reuse materials instead of treating them as if they are gone forever.