Aluminum and Hydrochloric acid react violently. For instance if you have ever seen a Drain-o bomb using a plastic bottle, the combination of the 20% HCl concentration and the aluminum foil creates heat and boil releasing steam, bottle becomes unable to contain it and explodes, releasing the steam rapidly. Answer course correction: Drano is composed of Sodium Hydroxide, sodium nitrate and aluminum. The above observations are true but it's an NaOH/Al reaction giving the heat and gas. The 'grease cutting" is a result of the hot hydroxide saponifying the fats (turning them to soap) which are then soluble in water. (6NaOH + 2Al --> 3H2 + 2Na3AlO3) The reaction of Aluminum and HCl: 2Al + 6HCl --> 2AlCl3 + 3H2 All in al it looks the same (fizzes)and gets hot.