California Cosmetology Chemistry & Products Practice Questions
About 12% of the California written exam tests how well you understand the products you use every day. You will see questions about pH, hair color categories, peroxide developer volumes, hair relaxers and waves, skin care actives, and the Safety Data Sheets required by Cal/OSHA. You do not need a chemistry degree, but you should know what a product does, why it works, and how to use it safely on your client. This chapter walks through the chemistry you need in plain language with the key California rules cited.
Sample Chemistry & Products questions
1. On the pH scale, which value represents a neutral solution at room temperature?
The pH scale runs from 0 to 14. A value of 7 is neutral (the pH of pure water). Below 7 is acidic; above 7 is alkaline.
2. What is the approximate natural pH range of healthy hair and skin?
Healthy hair and skin sit in a slightly acidic range of about 4.5 to 5.5. This is often called the acid mantle and helps protect against bacteria and moisture loss.
3. A change from pH 5 to pH 7 represents how much of a change in hydrogen ion concentration?
The pH scale is logarithmic, so each whole number is a tenfold change. Two units (pH 5 to pH 7) means the solution is 10 x 10 = 100 times less acidic.
4. Sodium hydroxide hair relaxers (commonly called 'lye relaxers') typically have a pH of approximately:
Sodium hydroxide relaxers are very alkaline, with a pH of about 12 to 14. The high pH swells and breaks disulfide bonds quickly, so processing must be timed carefully to avoid scalp burns.
5. Which statement best describes a 'no-lye' relaxer compared to a 'lye' relaxer?
No-lye relaxers most commonly use guanidine hydroxide (mixed on site from calcium hydroxide and guanidine carbonate). They are generally less irritating to the scalp but can leave more mineral deposits, making hair feel drier.
6. Which chemical bond is broken when hair is permanently waved or relaxed?
Permanent waving and chemical relaxing both break and reform the disulfide bonds in keratin. Hydrogen and salt bonds are only temporarily broken by water or heat styling.
7. In a cold permanent wave, which chemical acts as the reducing agent that breaks disulfide bonds?
Cold waves use ammonium thioglycolate (ATG) as the waving lotion. It is a reducing agent that breaks disulfide bonds at room temperature. The neutralizer (usually hydrogen peroxide or sodium bromate) then re-forms the bonds in the new shape.
8. The neutralizer applied after the waving lotion in a permanent wave is an example of what type of chemical reaction?
The neutralizer (typically hydrogen peroxide) oxidizes the broken disulfide bonds, allowing them to re-form in the curled shape. Even though the product is called a 'neutralizer,' the chemistry is an oxidation reaction.
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