Nitrocellulose

Cellulose hexanitrate, commonly called nitrocellulose, is a very interesting explosive. When ignited unconfined, it bursts into a large ball of flame. This happens so fast that it's actually safe to ignite it on your hand. When the nitrocellulose is tightly confined it detonates, resulting in a violent explosion. Nitrocellulose was first prepared by Henri Braconnot in 1832. The synthesis of nitrocellulose is a chemistry classic.

Nitrocellulose is usually prepared from sulphuric and nitric acids, however I substituted the nitric acid with potassium nitrate.

To a beaker in an ice bath, I added 50ml of 98% sulphuric acid. I let the acid cool for 5 minutes, then over the course of 30 minutes added 25g of potassium nitrate in portions. This forms the required nitric acid in situ. After the nitrate addition, using a glass stir rod, I pushed pieces of cotton wool in until no more could be covered by the mixture. I left this overnight. The cellulose in the cotton reacts with the acids to form nitrocellulose. Anyway the next morning, I removed the nitrocellulose and added it to a bucket of water. I left it in the bucket for about 15 minutes to soak, then swirled it around in the water until it uncaked and started looking like cotton wool again.

I washed the nitrocellulose with 500ml of saturated sodium bicarbonate solution to remove traces of sulphuric/nitric acid. Then I washed it with water again to remove the sodium salts from the product.
I then dried it. I couldn't weigh the nitrocellulose as the pieces were too big to fit on my scales.

Left = dry nitrocellulose  /  Right = nitrocellulose deflagration unconfined
H2SO4 + KNO3 ==> HNO3 + KHSO4  /  HNO3 + 2 H2SO4 ==> 2 HSO4 (-) + NO2 (+) + H3O (+)