Properties of Gases and Derivation of Gas Laws (Parts B, C, and D only)

There are two ways to assure success for this lab

• Take very good care of the micro capillary tube
• Do not drop, shock, or shake the micro gas capillary tube.
• Make great entries into your lab notebook. Do not trust anything to memory.
• Write everything down. EVERYTHING! Especially the length of the Hg slug and the air slug.
• Label everything as to what you are doing
• Making sure you use all the decimal places even if it is a zero
• Guess the next decimal place that cannot be read directly to within a half or a third
• Write down every unit

• Each group of 4 students should have a different student set up a different temperature bath for Part C.
• The ice water bath
• This should be almost all ice. There should be just enough water to make the ice easy to move around
• The ice/salt water bath
• Same as above but add salt.  This is a demonstration of freezing point depression.
• The 60 °C bath
• Set this one up early to insure that the temperature is stable.  It may require a bit of adjusting.  As you are performing part B of the experiment you can work to get the temperature right.  It is easiest to start low, about 2, turn the temperature up a little bit at a time, let it stabilize, and repeat as necessary.  If it gets too hot you can add some cold water to bring the temperature down quickly and then adjust the heat control down.  Let the system stabilize and then adjust again.
• If you used tape to hold the micro gas capillary tube you may find that the tape's adhesive qualities are not working as well as they did in the cold baths.  Be careful or use twist ties.
• The 100 °C bath
• Turn the heat up on this one.  As long as it does not go dry, depending on the atmospheric pressure, water will attain a temperature close to 100 °C and stay there.  Do you know why?

When setting up your temperature baths do so near the edge wall of your hood.  You can use masking tape to hold the thermometer suspended in the bath.  You do not want it to touch the sides or bottom of the beaker.  You want to know the temperature of the bath not the beaker.  They are different.

You can tape the cardboard angle indicators to the front of your hood.

Do not bias your data.  Make each series of measurements in Part B completely before repeating.  For the temperature baths allow the micro gas capillary tube to return to room temperature or switch to a different temperature bath.  You can warm it in your hand or cool it by laying it on the bench top or by holding it under running water or by switching baths.  Try not to look at the previous entry made under similar conditions when making the repeat measurement.  Try to use the same equilibration times.