N 2 is a gas which occupies much more volume than the solid does. The reaction heats up small pieces of Al to the point that they glow. Hydrogen chloride is HCl in the gas phase.
Hydrochloric acid is HCl dissolved in water.
The cloud is finely dispersed NH 4 Cl powder. It is less dense than air. It is very flammable. The volume of O 2 produced should be half that of the H 2 produced. 2 O 2 is very commonly used in your house.