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There are a variety of methods by which a sample's boiling point can be determined, including distillation, reflux, and by using a Thiele tube. The most straightforward method uses a Thiele tube, and has the advantage of using less than 0.5mL 0.5 mL of material.
There are two ways in which a pressure nomograph can be used (i) to determine the boiling point at atmospheric pressure (760 mm Hg) given the boiling point at a lower pressure and (ii) to determine the boiling point at a lower pressure given the boiling point at atmospheric pressure.
Model 1: Boiling Points Change Down a Group of the Periodic Table. Molecules are held in the liquid phase due to intermolecular forces so that boiling points are a good guide to their strength. The figure opposite shows the boiling points of the Group 14 hydrides.
Problem #1: What is the molecular mass of an organic compound if 16.00 g of the compound is dissolved in 225.0 g of carbon tetrachloride raises the boiling point to 85.36 °C? Solution: 1) We need to look up the ebullioscopic constant of CCl 4 as well as its boiling point:
Boiling Point Determination Procedure. Make a test-tube assembly by using the following directions and illustration. Place about 1 mL of your liquid in a small test-tube. (If you have 1mL) Using a small rubberband, attach a thermometer to the outside of the test tube.
Prior knowledge. The boiling point of water. Rationale. This activity is designed to help students develop their critical thinking (evaluative) skills. They are presented with a surprising measurement for the boiling point of water and several suggestions as to why it might be. The main task is to evaluate the different suggestions.
Boiling Point. liquid boils at the temperature at which its vapor pressure equals the atmospheric pressure. For all liquids, as heat is applied, molecules move with greater kinetic energy.
