Corrosive

Malay: Menghakis · Chinese: 腐蚀性

Corrosive describes a chemical that attacks and damages living tissue or materials the moment it touches them. The key word is contact: a corrosive substance burns the skin, harms the eyes or eats into surfaces on direct contact, without needing to be swallowed or breathed in. Concentrated acids such as sulfuric acid and concentrated alkalis such as sodium hydroxide are common corrosive chemicals. In the SPM Chemistry papers (4541), a question often shows the corrosive symbol and asks for the matching precaution.

For example, when handling concentrated hydrochloric acid you wear safety goggles and gloves, avoid any skin contact, and mop up spills at once with plenty of water. The precaution follows directly from the hazard: because the danger is contact, you protect the surfaces that could be touched, chiefly the eyes and skin. This is also why corrosive liquids are added carefully and never splashed, and why the eyes, which are especially vulnerable, are protected first with goggles.

The confusion to avoid, and one of the most examined distinctions in this chapter, is between corrosive and toxic. Corrosive is about damage on contact; toxic is about being poisonous if taken into the body by swallowing, breathing in or absorption. A concentrated acid is corrosive; a poison that harms you only once inside the body is toxic. A chemical can even be both, but the words describe different dangers, so match the precaution to the right one.

Within the safety section, corrosive sits beside toxic and flammable as the everyday hazard classes you must recognise, and it links to the hazard symbol on the container and to wearing goggles. Our teachers drill the corrosive-versus-toxic distinction so you never pair a hazard with the wrong precaution.