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Molar Mass by Freezing Point Depression—AP* Chemistry Classic Laboratory Kit

By: The Flinn Staff

Item #: AP6356

Price: $30.20

With the Molar Mass by Freezing Point Depression Classic Lab Kit for AP* Chemistry, students calculate the freezing depression constant for BHT by measuring known freezing point values and calculating the molar mass of an unknown.

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Classic AP Requirement #4—Determination of Molar Mass by Freezing Point Depression

Determine the molar mass of an unknown by measuring the freezing point depression of its solution with BHT (2,6-Di-tert-butyl-4-methylphenol). The freezing point of BHT is first determined, followed by the freezing point of a solution of the known substance dissolved in BHT. The freezing depression constant, kfp, for BHT is calculated by measuring the freezing point for known solutions and is then used to calculate the molar mass of the unknown. Students gain the recommended familiarity with the observation and recording of phase changes. An alternative microscale procedure is included as a supplement.

Complete for 24 students working in pairs.

Molar Mass by Freezing Point Depression Inquiry Guidance & AP* Chemistry Curriculum Alignment Transition Guide available! Follow the link in Resources to find this valuable publication that lets you adapt this classic AP Chemistry experiment for guided-inquiry and correlate with the AP Chemistry curriculum framework.


Materials Included in Kit (for 24 students working in pairs): BHT, cetyl alcohol, stearic acid.

Additional Materials Required (for each lab group): 0.001-g precision balance (shared), beaker, capillary tubes, hot plates or Bunsen burners, mortar and pestle, ring stand, ring clamp, rubber bands, rubber stopper with one hole, stirring rods, support stands, 18 × 150 mm test tubes, thermometers (preferably graduated to 0.1 °C), Thiele melting point tubes (optional), universal clamp, watch glass, weighing paper, wire gauzes, wire stirrers.

*Advanced Placement and AP are registered trademarks of the College Board, which was not involved in the production of, and does not endorse, these products.