Cosmetology Licensing and Regulations Practice Test

During a chemical hair straightening treatment, a chemical change occurs primarily due to the breakage of disulfide bonds within the hair structure. Hair is made up of a protein called keratin, which has numerous disulfide bonds that give it strength and shape. The straightening process involves the application of a chemical solution that breaks these bonds, allowing the hair to be reshaped and straightened.

Once the disulfide bonds are broken, the hair can be restructured into a straight form. Following this, a neutralizing solution is often applied to reform the disulfide bonds in their new, straightened position. This entire process is classified as a chemical change because it fundamentally alters the composition of the hair's chemical structure. The ability of the hair to maintain a new shape after the treatment is a direct result of this chemical reformation process.

Other types of reactions mentioned do not capture the essence of what occurs in a chemical straightening treatment. A physical change does not involve altering the chemical structure, while thermal reactions pertain to heat-induced changes without the breaking of chemical bonds. An oxidation reaction, although it can occur in some chemical treatments, is not the main reaction during the straightening process. The breaking and reforming of dis