Mean, nasty, and caustic as the worst acid, vitriolic words can hurt feelings, break hearts, and even lead to violence.
Vitriolic is an adjective related to the noun vitriol — which means a metal sulphate. However, you will most likely NOT hear vitriolic used to describe a chemical reaction. You are more likely to hear vitriolic used to describe caustic words. We've seen some examples in recent political campaigns, and the results are always embarrassing. Avoid using vitriolic language whenever possible, and you will keep your friends — and your dignity.