NIC Nail Technician Written ExamScientific ConceptsHard
A technician is preparing a disinfection solution for implements. If the manufacturer's instructions call for a 1:10 dilution ratio and the technician needs 1000 ml of solution, how much concentrate should be used?
- A200 ml
- B50 ml
- C10 ml
- D100 ml
Show answer & explanationAnswer & explanation
Correct answer: D. 100 ml
A 1:10 dilution ratio means 1 part concentrate to 10 parts total solution. So, for every 10 parts of solution, 1 part is concentrate. To find the amount of concentrate needed for 1000 ml of solution, divide the total volume by the dilution sum (1+10=11), then multiply by the concentrate part (1). More simply, divide the total volume by 10 (the 'parts' of solution for 1 part concentrate). 1000 ml / 10 = 100 ml.
Why the other options are wrong
- A. Incorrect; 200 ml would be a 1:5 dilution for 1000 ml.
- B. Incorrect; 50 ml would be a 1:20 dilution for 1000 ml.
- C. Incorrect; 10 ml would be a 1:100 dilution for 1000 ml.
Dilution Ratios
A method of expressing the concentration of a solution, indicating the ratio of concentrate to total solution (e.g., 1:10 means 1 part concentrate to 9 parts water for a total of 10 parts solution).
- Expressed as 'parts concentrate : total parts solution' or 'parts concentrate : parts solvent'
- Essential for proper efficacy of disinfectants
- Incorrect dilution can render disinfectants ineffective or corrosive
Memory trick: Ratio math: 'Total' over 'Ratio number' gives 'Concentrate'.