You are asked to identify an unknown liquid that is known to be one of the liquids listed below. You pipet a 3.50-mL sample into a beaker. The empty beaker had a mass of 12.20 g, and the beaker plus the liquid weighed 16.08 g.
Substance Density at 25 °C (g/cm3)
Ethylene glycol 1.1088 (major component of automobile antifreeze)
Water 0.9971
Ethanol 0.7893 (alcohol in alcoholic beverages)
Acetic acid 1.0492 (active component of vinegar)
Glycerol 1.2613 (solvent used in home care products)
(a) Calculate the density and identify the unknown.
(b) If you were able to measure the volume to only two significant figures (that is, 3.5 mL, not 3.50 mL), will the results be sufficiently accurate to identify the unknown? Explain.