Final answer:
To prepare a 100mL infusion containing 3.6g of a solute from an 18% solution, 20 mL of the original solution is required.
Step-by-step explanation:
To determine how many mL of an 18% solution should be used to obtain 3.6g in a 100mL infusion, we need to use the concept of dilution and concentration calculations in chemistry. Firstly, we should calculate the mass of the solute in the original 18% solution. The mass of the solute in 100mL of an 18% solution is calculated as follows:
Mass of solute (g) = Volume (mL) × Concentration (%) × Density (g/mL) (assuming density is approximately 1 g/mL for dilute solutions)
Therefore, the mass of the solute in 100mL is:
Mass = 100 mL × 0.18 = 18g
Since we require 3.6g of the solute, we calculate the volume of the 18% solution needed, using a simple proportion:
(Volume needed) × (Mass of solute in original solution) = (Total volume) × (Required mass of solute)
V1 × 18g = 100mL × 3.6g
V1 = (100mL × 3.6g) / 18g
V1 = 20mL
Therefore, 20 mL of the 18% solution will be used to prepare a 100mL infusion containing 3.6g of the solute.