Intermolecular Forces Lab
(No formal lab report required.� Just complete this sheet and follow its instructions.)
Purpose:� The purpose of this lab is to determine the relative strength of the intermolecular forces between water, ethyl alcohol, and acetone.
- Find a thermometer that has no gaps in the liquid inside the thermometer.� If your thermometer contains mercury, be especially careful not to break the thermometer.
- Tear a C-Fold paper towel in half.� Tear each of the resulting pieces in half.� Tear those four pieces in half.
- Tightly wrap one of the eight pieces of paper towel around the end of the thermometer containing the liquid reservoir.� Use masking tape to securely and tightly hold the paper towel piece in place, keeping the masking tape as far away from the liquid reservoir as possible.
- Dip the thermometer bulb into a test tube of water that is at room temperature.� Take care not to get any water on the masking tape.� Record the temperature reading on the thermometer before you remove it from the liquid.� Always be as precise in your temperature readings as possible.� (Remember this hint on all future labs involving thermometers.)
- Start your stopwatch as you remove the thermometer from the liquid and immediately position the bulb of the thermometer in front of a fan that is set to its highest speed possible.� Try to position the bulb where the airspeed is highest.
- Record the lowest temperature that is reached and record the time required to achieve that temperature.
- Remove the masking tape and paper towel.� Wipe the thermometer dry and allow it to return to room temperature.
- Repeat steps 3-7 for ethanol, by dipping your thermometer into the small Erlenmeyer flask filled with ethanol.
- Repeat steps 3-7 for acetone, by dipping your thermometer into the small Erlenmeyer flask filled with acetonel.
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Questions (Answer on a separate piece of paper and staple it to this sheet):
- Draw a Maxwell-Boltzman distribution for these specific experiments, and use your diagram to explain why the temperature dropped in the above experiments.
- Draw a separate Maxwell-Boltzman distribution that you can use to answer each of the following questions:� Which of the three liquids has the lowest intermolecular forces based on your data?�Which has the highest?� Explain your answers based on the intermolecular forces and/or molecular geometry of each molecule.
- Using a different Maxwell-Boltzman distribution than those you drew for questions 1 & 2, explain why one of the liquids had a greater temperature drop than the others?
- Which of the three liquids should have the lowest b.p.?� Which should have the highest?