These products don't contain ammonia, meaning the hair shaft isn't opened up during processing and the hair's natural color is retained once the product washes out.
Bleach is used to lighten people's hair. The bleach reacts with the melanin in the hair, removing the color through an irreversible chemical reaction. The bleach oxidizes the melanin molecule.
The melanin is still present, but the oxidized molecule is colorless. However, bleached hair tends to have a pale yellow tint. The yellow color is the natural color of keratin, the structural protein in hair. Also, bleach reacts more readily with the dark eumelanin pigment than with the phaeomelanin, so some gold or red residual color may remain after lightening. Hydrogen peroxide is one of the most common lightening agents. The peroxide is used in an alkaline solution, which opens the hair shaft to allow the peroxide to react with the melanin.
The outer layer of the hair shaft, its cuticle, must be opened before permanent color can be deposited into the hair. Once the cuticle is open, the dye reacts with the inner portion of the hair, the cortex, to deposit or remove the color. Most permanent hair coloring products use a two-step process usually occurring simultaneously which first removes the original color of the hair and then deposits a new color.
It's essentially the same process as lightening except a colorant is then bonded to the hair shaft. Ammonia is the alkaline chemical that opens the cuticle and allows the hair color to penetrate the cortex of the hair. It also acts as a catalyst when the permanent hair color comes together with the peroxide. It is not a chemical reaction because it only alters the physical properties of the water.
Ice is still H2O, water vapor is still H2O; the chemical properties remain the same. The energy required to fuel a chemical reaction is activation energy. Water boiling, melting ice, tearing paper, freezing water and crushing a can are all examples of physical changes. On the other hand, chemical changes are a bit different.
A B glass breaking physical change hammering wood together to build a treehouse physical change buring toast chemical change frying an egg chemical change. In each of these examples, there is a change in the physical state, form, or properties of the substance, but no change in its chemical composition. The explosion of nitroglycerin is a chemical change because the gases produced are very different kinds of matter from the original substance.
For example: When water H 2 O changes from solid ice to liquid water , that is a physical change. The chemical makeup hydrogen and oxygen is not altered. When salt and sugar dissolve in water it is a physical change.
The chemical makeup of the salt and sugar are not changed. Melting chocolate is physical change because the chocolate has changed from a solid to a liquid. Chocolate is a physical change because you can change melted chocolate back into solid chocolate.
Some more examples of physical changes are tearing paper into smaller pieces, sharpening your pencil , and stirring sugar into water. When you tear a piece of paper, it is still paper; it's just that the pieces are smaller.
That is a physical change ; a change you can easily see. Write Your Answer. Similar Asks What are the elements of bleach? Is it safe to pour bleach down the drain? Is bleach acidic or basic?
Is bleach safe? What exactly is bleach? Why is bleach basic? Hydrogen peroxide is one of the most common lightening agents.
The peroxide is used in an alkaline solution, which opens the hair shaft to allow the peroxide to react with the melanin. User login Username. Create new account Reset your password.
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