NIC Esthetician Written ExamScientific ConceptsHard
A cosmetic formulator is developing a new product with a pH of 4.5. If the product's pH is adjusted to 3.5, how many times more acidic has the product become?
- A10 times
- B100 times
- C5 times
- D2 times
Show answer & explanationAnswer & explanation
Correct answer: A. 10 times
The pH scale is logarithmic, meaning each whole number change represents a tenfold (10x) difference in acidity or alkalinity. A change from pH 4.5 to pH 3.5 is a difference of 1 pH unit, making the product 10 times more acidic.
Why the other options are wrong
- B. This would indicate a change of 2 pH units (e.g., from 4.5 to 2.5), which is not the case here.
- C. This is incorrect; the difference is 1 pH unit, not 5 pH units.
- D. This would be incorrect as the pH scale works in factors of 10, not 2.
pH Scale Logarithmic Nature
The pH scale is logarithmic, meaning that each whole number change in pH represents a tenfold (10x) difference in hydrogen ion concentration, and thus in acidity or alkalinity.
- Each pH unit represents a 10-fold change
- Lower pH = more acidic (higher H+ concentration)
- Higher pH = more alkaline (lower H+ concentration)
- A change of 1 pH unit = 10x difference; 2 pH units = 100x difference
Memory trick: pH Power: Each Point Pushes Ten-fold.