The Calibration of a Thermometer

Calibration of a Thermometer

By:

Thor Klein

Ruby Elson

Introduction

The purpose of this lab was to accurately calibrate an alcohol thermometer to tell the temperature using a scale that we created.  A thermometer is used to accurately display a temperature of a substance.  For example, if someone wants to find the room temperature of water, one way to find it is to place a thermometer in the water and read the temperature displayed.  There are two types of thermometers; alcohol thermometers and mercury thermometers.  We used alcohol thermometers because of the dangers that come along with mercury thermometers.  The liquid inside the thermometer (alcohol), expands up the bore of the thermometer when heated, and when placed in a cool environment, the liquid condenses and drops.  This allows someone to read where the liquid is on the scale of the thermometer, which portrays the active temperature.

Materials

• Two Beakers
• Distilled Water
• Tape
• Sharpie
• Ice
• Hot Plate
• Plastic Sheet
• Meter Stick
• Blank Thermometer

Procedure

1. 1. Obtain both Plastic Sheet and Blank Thermometer. Using the tape, securely attach the blank thermometer to the center of the plastic sheet

   2. 

      Boiling H20! See Steps 2-3

      Fill one beaker about ⅔ of the way up with distilled water. Then, set it on the hot plate and wait for it to boil
   3. After the water is boil, place thermometer about a centimeter off of the bottom of the beaker, completely submerging it without touching the bottom or sides.  Hold for about two minutes, or until the alcohol within the thermometer stops moving.
      
      
   4. Mark the spot where the alcohol stopped moving with sharpie on the plastic. On that line, write 100 C.

   5. 

      See steps 6-7

      Take thermometer out of water, and turn off the hot plate. Before moving on to the next step, allow the thermometer to go back to room temperature.
   6. With the second beaker, fill it up ⅔ of the way with an even mixture of ice and distilled water.
   7. Submerge the thermometer in the ice water about 3 centimeters off of the bottom, and in the center. Stirring every so often allows the temperature to be even throughout the entire beaker. Hold for about two to three minutes, or until the alcohol stops moving.
   8. Where the alcohol line is, mark it with a sharpie on the plastic. Next to the line, write 0 C.
   9. Remove thermometer and grab the meter stick.

   10. 

       Measuring, see step9-11

       Measuring between the 100 and 0 C mark, draw a line at the exact middle of the two. There, write 50 C.
   11. Continue to measure using increments of ten from the 50 mark line to the 0 mark line. Repeat from the 50 mark line to the 100 mark line.
   12. Between each ten mark line, measure the middle, and then mark another little line, the 5 mark line.
   13. .In order to be sure that the thermometer works well, try testing it. By having another person (i.e teacher, friend, adult) give you a beaker full of an unknown substance that you must measure with your new thermometer, you are able to find out the level of accuracy. Provided, of course that the other person already knows the temperature of that unknown substance.
   
   
   
   Extension

   1. 1. 

          Our finished thermometer measuring out a temperature 

         Since we now know how to accurately scale a thermometer, we can use these skills to create other measuring tools.  One tool we could create is a scale used for comparing the weight of two substances because of our new knowledge in scales.  We would scale the balance so each side would be equal, then we could place two objects on either side, then whichever side bends down the most, we would know that object would be heavier.
      2. The reason why it was so important to use distilled water was that not only is it an easily accessible resource that’s cheap, it also has known boiling and freezing points. Rather than using tap water, distilled water has no added substances, thus giving us a more accurate reading of the boiling and freezing points of water.
      3. There were many sources of error in this experiment.  One possible error that could have altered our results was when we taped the thermometer down, it moved a little which caused the scale to be a little less accurate.  Another source of error in this experiment was measuring the scale with our ruler.  We had to mark each interval with a sharpie and the lines weren't exactly in place when we marked them.  A third source of error is when we took out the thermometer from the freezing and boiling water, we had to mark where the liquid was with our finger, which wasn't as precise as it could have been.
      4. The level of precision we chose was to the nearest 5th. By measuring to the nearest 5th, it allowed us to gain a more accurate measurement than say to the tenth. This created less of a room for error, but at the same time, kept the scale neat because it left out each tiny dash mark between each interval.