Unformatted text preview: r the Pasco system start off basically analog voltages. We must start
by telling the system what voltages correspond to what temperatures. In so doing, we
will take advantage of two simple facts; water freezes at 0o C and boils at 100o C. Thus,
thermometers are not necessary at these temperatures since we know them. (In fact, these
temperatures are the basis of the Celsius temperature scale; this is not a coincidence.)
1. Start the computer, and the Pasco software. Choose the “temperature probe” analog
sensor. Be sure that you select position “A” and that you have the temperature probe
plugged into this port.
2. Choose “calibrate”; to your Styrofoam cup, add about equal quantities of ice and
water. Put the temperature probe into the ice water and allow a few minutes to
equilibrate. Choose the low temperature as “0.00”; make sure the units are set for o C. As
soon as the reading seems to have stabilized, click “read”.
3. Follow this step exactly as written; the faster you can do the last part of it, the better
your results will be. For the high temperature calibration, set the temperature to “100”.
Empty out your calorimeter. Then, as quickly as you safely can, fill the cup with boiling
water, return to your desk and quickly place the temperature probe into it and put the lid
on it. Remember that you are handling boiling water; don’t rush. Walk carefully back
to your desk. If something slows you down, we can always start over again; it is not
worth putting yourself or others at risk for burns by rushing or working recklessly. As
soon as the reading has stabilized, click “read”.
If you followed these instructions carefully, your Pasco system should be ready. Dakota State University page 178 of 232 Experiment 17: Calorimetry General Chemistry I and II Lab Manual Data Collection:
In the front of the room are several samples of objects in boiling water, including
glass and metal. These have a known starting temperature (what is it?). You will be
asked to calculate the specific heat of all of them. To do so, you will want to collect data
(1) If you have not already done so, close the calibration window.
(2) Click on “sampling options”. Select “slow” and move the slider until “10s” is
selected. This will take a data point every 10 seconds once the run is started.
(3) Open “table” and “graph” by dragging the appropriate icons over the thermometer
(4) Fill the calorimeter with water, then empty the water out. Without drying, measure
and record the mass of the calorimeter. Do not forget to “tare” be balance before placing
it on the scale.
(5) Fill the calorimeter about 2/3 full of water. Measure and record the mass of the
calorimeter with the water in it.
(6) Place the temperature probe into the calorimeter water and place the lid over the
calorimeter. Click “record” and allow at l ast 2 minutes of data collection (12 data
points). If, after this time, the temperature looks stable to you, without stopping the data
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