How to Show a Redox Reaction in the Bleaching of Hair

measurig cup image by Adkok from

A redox reaction is the reduction-oxidization of a substance that results when individual atoms have their state of oxidation number changed. This means the size and reactive properties of the substance is reduced and this change has been created with an application of an oxidizing chemical. When an oxidizer is applied, some electrons are removed and the substance's mass is reduced. A perfect example is the changing of brunette to blond hair with the application of hair bleach, where the target substance is the melanin protein found in human hair and the oxidizer is ammonia.

Flatten out a thin piece of foil on a clean surface. Lay the hair strand lengthwise from end to end on the foil. Keep a paper towel or other absorbent cloth handy when carrying out this experiment.

In a clean glass or plastic bowl, mix 1 oz. of the bleach powder with 2 oz. of the liquid hydrogen peroxide. This will form a paste. Thicker is better and it should be the same consistency as thick mud or toothpaste. If the mixture is too runny, add some more bleach powder; if too thick, add a bit more of the peroxide developer solution.

Dip the brush into the bleach solution. Holding the hair strip onto the foil with one hand, paint a thick layer of the bleach mixture onto the hair, using the foil as a base. Thoroughly saturate all of the hair strand. Fold the foil in half, then crimp the edges to make a packet.

Using the blow-dryer, heat the foil packet for about 30 seconds until the packet is very warm. Set a timer for 20 minutes. After 20 minutes, gently open the foil packet, avoiding contact with skin. Note the changes of the hair color and the consistency on the hair strands themselves. The hair should be light yellow and the hair strands will be much softer and more delicate. Rinse the hair while it is still in the foil packet to remove the bleach solution. Blot the excess moisture with the paper towel.

Using the blow-dryer, dry the hair. Note the change in the actual hair strands. They will be much lighter from the bleaching agent. The melanin protein in the hair has now been oxidized, causing the molecules themselves to shrink and become weaker. The hair can also stretch much further, indicating an increase in elasticity caused by the weakening of the melanin protein.