Chemistry in My Life: Hair Dye
By Brianna Prange
Where to Find the Reactants
Lightening: Bleach reacts with the melanin present in hair, by removing the color, this process is irreversible. The bleach oxidizes the melanin molecule, which makes it colorless. Bleached hair has a yellowish tint because keratin's natural color is yellow, so this color still shows, even though the melanin is now colorless.
Reactants: Hydrogen Peroxide is the most commonly used lightening agent, it is used in combination with an alkaline solution. The Alkaline solution opens up the hair shaft, which allows the peroxide to react with the melanin inside hair. Ammonia is usually the alkaline chemical that opens up the hair shaft to let the hair color inside the hair. Ammonia also acts as a catalyst when the permanent hair color mixes together with the peroxide. Peroxide breaks all of the chemical bonds in hair, in doing this it releases sulfur, which is why hair color has a distinctive odor. As the melanin becomes colorless, the new hair color is attached to the hair cortex, creating a whole new look.
Bleach: It is a man-made product that is formed by sending an electric current through a sodium chloride solution (table salt and water.) The electric current splits the atoms and the product is chlorine and caustic soda. Bleach can be found in any department store in the cleaning section.
Hydrogen Peroxide: Can also be called oxygen water, because it is water with one extra oxygen molecule. It is created when ultraviolet light strikes oxygen when moisture is present. It can also be make by treating barium peroxide with Sulfuric Acid. You can find in any pharmacy or department store.
Ammonia:Is made by the Haber-Bosch process which converts nitrogen present in the air into ammonia. Ammonia can be found in the cleaning department of stores. It also naturally occurs in cracks in the Earth by volcanoes.
Products and Byproducts/Environmental Impacts
Products/Byproducts: There are no byproducts of any of the reactants used in hair dye as far as I could find.
Environmental Impacts: These products can cause much harm when released into the environment. Water pollution is a main concern of these products, because they can cause harm to people and animals who ingest the contaminated water. It also can cause air pollution, which is also harmful to anyone who breathes it in.
Endo-or exothermic reactions?
Hair dye reactions can be either endothermic or exothermic depending on what type of hair dye you use. Endothermic hair dyes have to absorb outside heat from other sources, this is usually done by putting your hair under a hooded hair dryer. The heat activates the dye, allowing it to gain access to the inner hair shaft. Exothermic hair dyes use chemical reactions that produce their own heat. These dyes usually have 3 parts, a hair color, an activator, and a neutralizer. When these 3 components mix it causes a rapid release of heat, which triggers the reaction.
Who is Affected?
Anyone who dyes their hair would be affected by this chemistry. If the chemicals are released in the atmosphere or environment, then everyone would be effected by the pollution.
How Essential is the Chemistry?
This chemistry isn't really needed to live, so it isn't very important for everyday life. But, it is great to know if you don't like your hair color, or are going gray/white, you can change it. It is an useful type of chemistry, but isn't essential to live your life.
Hydrogen peroxide is also used for bleaching cotton, other textiles, and wood pulp. It can also be used as a rocket propellant.
Solutions of that contain more than 8% hydrogen peroxide are corrosive to the skin.
75% of women color their hair, and growing number of men are also starting.
3400 BC is the era in which Ancient Egyptians began using henna to camouflage their grays.
Only 9% of the population are natural blondes.
A $51,000 grant was awarded to an Australian grad student to study if blondes are actually dumb.