Matches are a tool that can generate heat by friction based on the principle of friction and heat generation of objects, using the chemical activity of strong oxidants and reducing agents to create a fire.
The matches we often use are called safety matches. The side of the match box is coated with red phosphorus (pyrophoric agent) and antimony trisulfide (Sb2S3, combustible); the substances on the match head are generally KClO3, MnO2 (oxidant) and S (flammable).
When the two have friction, the heat generated by the friction heats the red phosphorous in contact with KClO3, etc., causing the combustibles on the head of the safety match to burn, which makes the matchstick ignite.
The advantage of the safety match is that red phosphorus is not toxic, and it and the oxidant adhere to the side of the match box and the matchstick respectively, and they do not touch when not in use.
Ingredients of safety matches: Match head: oxidants (KClO3, MnO2), flammable substances (such as sulfur, etc.), adhesives.
Side of match box: red phosphorus, antimony trisulfide, adhesive.
Causes of fire: friction → heat → decomposition of KClO3 → ignition of red phosphorus → burning of combustibles (such as sulfur) on the head of the match.
Advantages: Red phosphorus is separated from the oxidant, which is relatively safe and non-toxic.
The predecessor of the safety match was based on the principle of applying a mixture of yellow phosphorus on the matchstick, which can catch fire if rubbed or hit on any hard surface.
In order to avoid danger, it is improved into a safety match. It must rub the red phosphorous side of the match box before it can catch fire. So it's called a safety match.
Friction matches can be ignited by friction on any rough surface. The manufacturing process of safety matches is to coat match heads with a mixture of potassium nitrate, carbon powder, glue, etc., with a mixture of tetraphosphorus trisulfide, lead oxide or other oxidants, glass powder and glue.
After the rough surface is rubbed, the heat generated by the friction makes the mixture of the outer layer play a violent action, which ignites the mixture of the inner layer, and then ignites the matchstick which has been soaked in paraffin oil.
In process of chemical experiments or making safety matches, red phosphorus is generally used, because red phosphorus is non-toxic and does not ignite spontaneously. The ignition point is above 200°C (about 260°C), and it burns in oxygen to produce phosphorus pentoxide, a white powdery solid.
(1) Because white phosphorus can ignite spontaneously and red phosphorus cannot ignite spontaneously, then the ignition point of red phosphorus is higher than that of white phosphorus; phosphorus reacts with oxygen to form phosphorus pentoxide under ignition conditions. The chemical equation of the reaction is:
(2) The phenomenon of iron wire burning in oxygen is: violent burning, sparks are emitted, a lot of heat is released, and a black solid is formed.
Iron reacts with oxygen under ignition conditions to produce ferroferric oxide. The chemical equation of the reaction is:
(3) When the clarified lime water is placed in the air, a white film is formed on the surface because the air contains CO2; in this reaction, the carbon dioxide reacts with calcium hydroxide to form calcium carbonate precipitation and water.
The chemical equation of the reaction is:
(4) SO2 can decolor the purple potassium permanganate solution; sulfur reacts with oxygen to form sulfur dioxide under ignition conditions.