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How to Identify a Solvent

A solvent is a solid, liquid or gaseous substance that dissolves another substance. Anything that is dissolved in a solvent is called a solute. For example, if sugar is dissolved in water to make lemonade, the sugar is the solute and water is the solvent. Together they form a solution. To identify a solvent in a solution you must first separate the solvent and solutes and then compare the substance to a known characteristic such as its boiling point, melting point or density. A common method of doing this is called fractional distillation.

Things You'll Need

Solution containing a solvent
Bunsen burner
Tripod and gauze
Beaker
2 boiling tubes with side arm
Delivery tube
Round-bottom flask
Bung
Test tube rack
Clamp stand and clamp
Thermometer
Boiling point identification chart

Instructions

Experiment Setup
- 1
  Set up the Bunsen burner underneath the tripod and put the mesh on the tripod ring. Fill a beaker halfway with water and then place it on the center of the tripod atop the mesh.
- 2
  Place the clamp stand near the tripod setup and adjust the clamp jaws so they securely hold the boiling tube.
- 3
  Slide the delivery tube onto the boiling tube arm and then position the clamp stand so that the bottom of the boiling tube is submerged in the beaker of water. Position a round-bottom flask near the tripod and clamp stand so that the delivery tube feeds into the flask. Be aware that you will be moving the boiling tube around to conduct the experiment.
Conducting the Test
- 4
  Remove the boiling tube from the water but leave the clamp, flask and tripod as they are. Put the boiling tube into the test tube rack.
- 5
  Turn on the Bunsen burner and begin to boil the water on the tripod. Place the solution containing the solvent you want to identify inside the boiling tube and attach the bung.
- 6
  When the water reaches the boiling point, turn off the Bunsen burner and then put the boiling tube, which contains the solution, back in place in the clamp stand as it was during the setup. The substance with the lowest boiling temperature then turns into gas and is distilled into the delivery tube, condensing in the flask as it cools down.
- 7
  Place the distilled substance from the flask into a clean boiling tube. Put the new boiling tube in the clamp jaws, which still is in the same configuration as during the setup. Place a thermometer in the water and then turn on the Bunsen burner.
- 8
  Watch the thermometer closely as the substance in the boiling tube heats up. Note the temperature of the water when the substance begins to boil. Compare this temperature to a chart of substance boiling points to identify your solvent. Find the chart in a chemistry text book or by asking a chemistry teacher or professor. Also, see Resources for a partial list.

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