Early chinese alchemists discovered an early form of gunpowder. what was the composition of this substance? what later developments were made to the gunpowder recipe that improved its pyrotechnic properties?

Sulfur, Charcoal and saltpetre. In about the 1860's, Gunpowder was used in firearms by guncotton and other, more stable forms of nitrocellulose. Unlike black powder, which burns by the chemical reactions of its constituent ingredients, nitrocellulose is an inherently unstable compound that burns by decomposing rapidly, forming hot gases. In contrast to black powder, it produces almost all gas upon combustion, earning itself the appellation smokeless powder. Also unlike black powder, nitrocellulose burns progressively, generating more gas pressure as combustion proceeds. This results in higher muzzle velocities (for the projectile) and less strain exerted on the firearm.Most forms of gunpowder produced today are either single-base (i.e., consisting of nitrocellulose alone) or double-base (consisting of a combination of nitrocellulose and nitroglycerin). Both types are prepared by plasticizing nitrocellulose with suitable solvents, rolling it into thin sheets, and cutting the sheets into small squares called granules or grains, which are then dried.

nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !