Chem can melt your opponent right out of their armor. All chem weapons cause armor damage equal to 0-20% of their Power, before armor's defense is even considered, unless otherwise stated in the Pedia. This makes subsequent shots more effective. The effect stacks with armor damage caused by any penetrating hits, if applicable. Chem also causes moderate Morale damage. However, the tradeoff is less armor penetration (usually 33%).