D5W intravenous fluid is 5.0% dextrose, C6H12O6, by mass and has a density of 1.029 g/mL. Taking the molecular mass of dextrose as 180 amu, what is its molarity?

1. Take exactly 1 L of the fluid so the answer comes out per litre. 2. Use the density to get its mass: 1000 mL x 1.029 g/mL = 1029 g of solution. 3. Apply the mass percentage: 1029 g x 5.0 / 100 = 51.45 g of dextrose. 4. Convert to moles with the molar mass of 180 g/mol: 51.45 g / 180 g/mol = 0.286 mol. 5. That amount sits in 1 L, so the molarity is 0.29 M. 6. Units check: mL x g/mL gives grams, and grams over grams per mole gives moles. 7. The value 5.7 M forgets the 5 percent step and converts the whole 1029 g as if it were all dextrose. 8. The values 2.9 M and 0.029 M are one decimal place slips either side of the answer. _Source: OpenStax Chemistry (CC BY 4.0), Ch 3 "Composition of Substances and Solutions", section 3.4 Other Units for Solution Concentrations_