Physiological saline is 0.9% mass/volume NaCl. How much NaCl is in 500 mL of it?

1. A concentration of 0.9 percent m/v means 0.9 g of solute in every 100 mL of solution. 2. A 500 mL volume is five times that 100 mL basis. 3. Multiply the solute mass by the same factor: 0.9 g x 5 = 4.5 g. 4. The value 0.9 g is the amount in only 100 mL, not in the full 500 mL. 5. The value 45 g would follow from a 5000 mL volume, a factor of ten too large. _Source: OpenStax Chemistry (CC BY 4.0), Ch 3 "Composition of Substances and Solutions", section 3.4 Other Units for Solution Concentrations_