Pure Glacial Acetic Acid, HC₂H₃O₂, Has a Molar Mass of 60.052

Short Answer

Pure glacial acetic acid, HC₂H₃O₂, has a molar mass of 60.052 g mol⁻¹ and a density of 1.0492 g mL⁻¹, a freezing point of 16.62°C, and a boiling point of 118.3°C. Its freezing point depression and boiling point elevation constants are: K_f = 3.57 °C m⁻¹; K_b = 3.07 °C m⁻¹. A solution was made by taking 19.51 g of an unknown nonelectrolyte and dissolving it in 181.0 g of glacial acetic acid. The measured freezing point of the solution was 8.64°C. Calculate the molar mass of the unknown substance.Hint: Find molality, then moles, then molar mass, being sure to keep track of units.