Wine is about 12% ethanol by volume. With ethanol at 46.06 g/mol and density 0.789 g/mL, how many moles are in 750 mL of wine?

1. Volume percentage gives the ethanol volume as 12 percent of the bottle. 2. That volume is 750 mL x 12 / 100 = 90 mL of ethanol. 3. Convert to a mass with the density: 90 mL x 0.789 g/mL = 71.0 g of ethanol. 4. Convert the mass to an amount with the molar mass: 71.0 g / 46.06 g/mol. 5. The amount is 1.5 mol of ethanol. 6. Units cancel at each stage, from mL to g and then from g to mol. 7. The value 12.8 mol skips the volume percentage and treats the whole bottle as ethanol. _Source: OpenStax Chemistry (CC BY 4.0), Ch 3 "Composition of Substances and Solutions", section 3.4 Other Units for Solution Concentrations_