Final answer:
To prepare the antiseptic solution, you need to dilute 41.67 mL of a 12% stock solution of benzalkonium chloride to a final volume of 1.0 L to achieve a 0.50% concentration.
Step-by-step explanation:
To prepare 1.0 L of a 0.50% benzalkonium chloride antiseptic from a 12% stock solution, we can use the dilution formula: (stock concentration) × (volume of stock) = (desired concentration) × (final volume of the solution). In this case, the desired concentration is 0.50% and the final volume is 1.0 L (1000 mL).
The formula setup is as follows:
(12%) × V1 = (0.50%)(1000 mL)
To find V1 (the volume of the stock solution needed), we rearrange the equation:
V1 = (0.50% × 1000 mL) / 12%
V1 = (5 mL) / 12%
V1 = 41.67 mL
Therefore, you will need 41.67 mL of the 12% stock solution to prepare the 1.0 L of a 0.50% benzalkonium chloride antiseptic solution.