Question

Which is used in preparing matchsticks?

• A. Chile saltpetre
• B. Indian saltpetre
• C. Red phosphorus
• D. Sodium bicarbonate

Hint:

Recall what is painted on the striking side of a matchbox, not the match head.

Answer 1

The Correct Option is C

Step 1: A modern safety matchbox works by keeping the two reactive ingredients, an oxidiser and a fuel, physically separated on two different surfaces, this is what makes it a safety match, it lights only when struck against its own box.
Step 2: The match head is coated with an oxidising agent, commonly potassium chlorate, along with a binder and some sulfur or antimony trisulfide. The striking surface on the side of the matchbox is coated with a paste containing red phosphorus mixed with powdered glass and a binder. When the match head is rubbed against this striking surface, friction converts a tiny amount of red phosphorus into white phosphorus, which is highly reactive and ignites instantly in air, and that flame then sets off the oxidiser and fuel in the match head. Red phosphorus is chosen because, unlike white phosphorus, it is far less toxic, does not glow in air, and does not ignite spontaneously at room temperature, so it is safe to store and handle in matchbox factories and homes.
Step 3: Chile saltpetre is sodium nitrate, mainly used as a nitrogen fertiliser and in some explosives, it is not used on the matchbox striking strip. Indian saltpetre is potassium nitrate, traditionally used in gunpowder and fireworks, not in the modern safety match striking surface. Sodium bicarbonate is just baking soda, it has no oxidising or ignition role at all.
Step 4: Because red phosphorus is the actual ingredient painted on the striking surface of a matchbox, option C is correct.