CHEMISTRY · Single correct · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
An unknown crystalline solid melts at −9∘C, sublimes readily at room temperature, and shows no measurable electrical conductivity in any state. To confirm that the solid is molecular rather than ionic, which additional experiment would provide the most direct evidence?
(a) Determine the molar mass of the vapor by mass spectrometry to look for discrete molecules.
(b) Test the solubility of the solid in a non-polar solvent such as hexane; high solubility would imply molecular character.
(c) Prepare an aqueous solution and measure its electrical conductivity to see whether mobile ions are produced.
(d) Strike the solid with a hammer and observe the fracture pattern to assess brittleness characteristic of ionic lattices.