WARFARE
The mix of hcemistry and war was introduced for the first time during the World War I, crating a chorine gas released from cylinders that was used by the Germans in an assault (J.B. Calvert.) As the gas was effective, they used it again.
The main use of chemistry in warfare is the creation of bioological gases, like Chloracetophenone (C6H5COCH2CL), commonly known as tear gas; it melt at 58°C and boils at 245°C.
For serious attacks the army may use Sarin, also known as GB, which is classified as a nervous agent. These types of gases are the most dangerous and toxic weapon; It can cause paralysis, convulsions, conscious loss and even respiratory insufficiency. Instead of harming our fellow brother, we should help each other.
There is a phrase that says "Hagamos una revolución/que nuestro líder sea el Sol/ y nuestro ejército sean mariposas/ por bandera y otro amanecer/ y por justicia comprender/ que hay que cambiar las espadas por rosas."
As you can see, the mankind finds a method to find a way to destroy within the knowledge; we discover the nuclear power, and we make bombs with it. This is the bad of chemistry, although we can say that has a lot og good things, like medicine.