A wooden cylinder (in the form of a thin disk) of uniform density and a steel hoop are set side by side, released from rest at the same moment, and roll down an inclined plane towards a wall at the bottom. The cylinder has a larger radius than the hoop, but the hoop weighs more than the cylinder.

Gas will most likely  fill the container 

So are u adding some additional catalyst

The chemical reactions lab we did is typically called a "copper plating lab,  because the acid solution cleaned the pennies and made the copper look shinier;   the acid solution cleaned the paperclips and made them look like pennies;   &   the copper from the pennies was removed, and then added to the paperclips.