Chapter 23, Problem 71A

Interpretation Introduction

Interpretation: A permanent hair waving can change the shape of hair needs to be explained. Chemical steps to change the shape of someone’s hair from straight to curly should be described.

Concept Introduction: A polymer is a material made up of macromolecules, which are very big molecules made up of several repetitive subunits. Both synthetic and natural polymers play significant and pervasive roles in daily life because of their wide range of features.

Answer to Problem 71A

In permanent hair waving, hair is treated with a reducing agent followed by oxidizing agent confirming giving a new shape to hair from straight to curly.

Explanation of Solution

Given Information: Long-chain polymers make up human hair. Whether straight or curly the hair depends on where the disulfide linkages (S-S) are located between the polymers. Waving lotion in permanent waves is a type of reducing agent and neutralizing agent used is an oxidizing agent.

In the chemical treatment of permanent hair waving, hair is wound on rods and then, treated with a reducing agent (Thioglycolate) which reduces the Cysteine (Hair Protein), breaking the S-S bridge of the Cysteine molecule due to which the hair fiber gets weakened followed by the process of oxidation with Hydrogen Peroxide which locks the new molecular confirmation of hair Proteins and confirms to give new curly shape to the hair.

Conclusion

In permanent hair waving, hair is treated with a reducing agent followed by oxidizing agent confirming giving a new shape to hair from straight to curly.