Depends on the cartridge, Early cartridges used black powder, Modern cartridges use smokeless powder, based on nitrocellulose and nitroglycerin. There are hundreds of different smokeless powders that have different recipes, grain shapes, and burning rates.
The gun powder does not detonate, it burns.
All firearms need: A projectile such as a bullet, gun powder to propel the bullet out of the barrel of the gun, and a cartridge to hold them together. Gun powder only explodes and the force from the explosion propels the bullet out of the barrel, basically. The cartridge is disposed of thereafter. A bullet will not move unless the gunpowder behind it explodes. This is the basic operation of a firearm/rifle.
powder
Depends on who makes it. Could be flake, ball, extruded, cylinder, etc..
Gun shows, gun shops. A very common rifle cartridge.
Ignites the powder.
A cartridge is a complete round of ammunition. It consists of the cartridge case, which holds powder, primer and projectile (the bullet).
It can be either a rifle or a pistol. The Bullet or Ball is loaded through the front of the barrel. These are considered "Black Powder Firearms" Some muzzleloaders are smooth bores and they can either be shotguns or muskets. In order for a long gun to be a rifle, whether it's a muzzleloader or a modern cartridge gun, is the rifling, or spiral twist in the barrel.
The Thompson is classified as a submachine gun because it fires a pistol cartridge (.45mm) not a rifle cartridge. Another example would be the German MP-40 which used a 9mm cartridge or the M3 "Grease Gun" which fired either .45 or 9mm.
It is the container for the propellant (gun powder) and a holder for the primer and the bullet. On firing, the case expands, gripping the walls of the chamber, and forms a gas tight seal.
A cartridge consists of a cartridge case with primer, the powder filling, and the bullet (the projectile). When a cartridge is fired, the primer ignites the powder, which burns, driving the bullet out of the barrel. The now empty cartridge case may be automatically ejected from the gun (falls to the ground) or may have to be ejected by hand- depends on the gun.
The only way to be certain is to remove the bullet with a bullet puller, empty out the powder, and weigh it.