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Rust stains in sink, toilet bowl, and bath due to soluble iron ions in the water
Cleansers often have strong bases & oxidizers and are frequently corrosive and caustic. Some jobs require acid cleansers, too.
3% disinfects cuts
6% bleaches hair
30% bleaches skin to white on contact (very corrosive)
98% hydrogen peroxide is used as oxidizer for rocket fuel.
Atmospheres of Planets in our Solar System
Air pollutants are usually oxidized molecules
A reaction like that of B&W film photography: Silver chloride white powder with a paper clip on top is exposed to a bright light, which darkens the AgCl as free Ag is formed
B&W Film Photography
Photography has many redox reactions (Color photography shown here)
Three invisible gases are involved in a fire: oxygen in, carbon dioxide out, and water vapor out. Plants are rich in potassium, and so are the ashes (potash is the source & etymology for potassium).
Combustion triangle (here in Spanish)
Three requirements for combustion:
Fuel (gaseous fuel)
Oxygen (or other oxidizer)
Ignition (heat, spark, or match)
To extinguish a fire, one must remove one (or more) of the three requirements
Remove the fuel (spread it out, cover it).
Remove the oxygen (cover the fire with a solid lid, smother it with carbon dioxide or water).
Remove the heat (soak it with water, spread it out)
Remove free radicals (radicals are needed for flames) [4th requirement would use a flame tetrahedron]
Sign for extinguisher location:
Fire suppression using Halons at an airport
Match for Ignition
Liquid wax moves up in wick by capillary action.
Gaseous wax burns when it reaches ignition temperature.
Steel wool in air & O2
Steel wool glows red-hot with a small flame in air.
That glowing steel wool bursts into a larger flame in pure oxygen.
(in German: reiner Sauerstoff)
Fuels burn faster and hotter in 100% oxygen than in air (20% O2) Blowtorch flame
Can melt through metals with an acetylene (& 100% oxygen) torch
Apollo 1 accident while training on launching pad 100% oxygen was used within the capsule. A fire started with seat materials that would not burn in 20% oxygen. Astronauts White, Grissom, and Chaffee died.
Fuels burn faster in pure (100%) oxygen than in air (20% O2)
Fuels burn even faster in liquid oxygen.
See video of charcoal lighting at Purdue and video of diamond burning in liquid O2
Space Shuttle Challenger accident, Jan. 28, 1986
Chlorine, Bromine, & Iodine
Halogens in water & dense organic solvent Chlorine water reduces bromide to bromine & iodide to iodine
Candle burns in chlorine gas
Candle continues burning until chlorine is used up.
The products are mostly solids (in comparison to the gases of a candle in air), so the smoke is much thicker.
Hydrogen burns in bromine vapor
Spontaneous combustion was starting in this stack of fiber boards. When smoke was detected, the stack was cut open to show the burned area. The stack insulates, holding in any heat generated by oxidation or pyrolysis. Rags used in linseed oil frequently combust spontaneously (i.e., without ignition).
Spontaneous Human Combustion cannot occur. Charles Dickens’ Bleak House (1853) describes a spontaneous human combustion, which Dickens believed could occur.
Hypergolic fuels need no ignition
Rocket fuels have no need for spark plugs or other ignition source.
These fuels and their oxidizers are so potent that they react on mixing and start their own flame (these are called hypergolic).