Calculate the mass in grams of 1.60 × 1024 molecules of ethylene glycol. The chemical formula for ethylene glycol is C2H6O2.?

Number of moles of C₂H₆O₂ = (1.60 × 10²⁴) / (6.022 × 10²³ /mol) = 2.66 mol

Molar mass of C₂H₆O₂ = (12.0×2 + 1.0×6 + 16.0×2) g/mol = 62.0 g/mol

Mass of C₂H₆O₂ = (2.66 mol) × (62.0 g/mol) = 165 g (to 3 sig. fig.)