NIC Cosmetology Written (Theory) ExamScientific ConceptsMedium
A cosmetologist is preparing to use a new disinfectant concentrate in the salon. The manufacturer's instructions state that the concentrate should be diluted at a ratio of 1:128. If the cosmetologist needs to prepare 1 gallon of disinfectant solution, how much disinfectant concentrate should they use?
- A4 fluid ounces
- B8 fluid ounces
- C0.5 fluid ounces
- D1 fluid ounce
Show answer & explanationAnswer & explanation
Correct answer: D. 1 fluid ounce
A 1:128 dilution means 1 part concentrate to 128 parts water. Since 1 gallon equals 128 fluid ounces, 1 fluid ounce of concentrate is needed for 1 gallon of solution.
Why the other options are wrong
- A. This would be a 1:32 dilution, which is four times stronger than required.
- B. This would be a 1:16 dilution, which is eight times stronger than required and potentially damaging.
- C. This would be a 1:256 dilution, making the solution too weak.
Disinfectant Dilution (1:X)
The process of mixing a concentrated disinfectant with water according to manufacturer's instructions to achieve the correct germicidal efficacy and safety.
- Ratio 1:X means 1 part concentrate to X parts water.
- Incorrect dilution can render disinfectant ineffective or harmful.
- 1 gallon = 128 fluid ounces.
Memory trick: Dilution is 'Divide to Get Liquid' – total volume divided by the ratio number.