Final answer:
A traditional normal saline IV solution contains 9.0 grams of NaCl per liter. For a 25-mL bottle of contact lens solution at physiological concentration (0.16 M), you would determine the grams of NaCl based on the molarity and volume. Mass/mass percent concentrations are calculated from the mass of the solute and solution, and dilution calculations are used to prepare a solution from a concentrated stock.
Step-by-step explanation:
The amount of NaCl in normal saline relates to the concentration of the solution. Specifically, a normal saline IV solution traditionally contains 9.0 grams of NaCl per liter of solution. A saline solution is often used for medical purposes, and its concentration is critical for matching the body's needs. For instance, the concentration found in physiological saline, which is used in contact lens solutions, matches the approximately 0.16 M sodium chloride concentration in our bodies. If you have a 25-mL bottle of this solution, to find the amount of NaCl, you would calculate based on this molarity.
Moreover, when preparing a normal saline solution of a different volume, such as 250 mL with a concentration of 0.16 M, the mass of NaCl needed is calculated from the molarity and volume. In this scenario, the solution preparation involves molarity and volume to determine the required grams of NaCl.
Furthermore, in some instances, the concentration of a solution is provided as a mass/mass percent. For example, if you have a 355 g saline solution with 36.5 g of NaCl, the mass/mass percent concentration can be calculated from these values.
To prepare a normal saline solution from a more concentrated stock solution, such as a 5.0 M NaCl solution, you would use dilution calculations to determine the necessary volume of stock solution to reach the desired final molarity of 0.16 M over the target volume of 500 mL.