To begin the experiment click the Launch button.

This Workroom requires the manual setup of MassTracker parameters within the Recording Wizard and Display Wizard.

Launching the MassTracker graphing program from this Workroom will automatically set the Recording Wizard to Snapshot mode with Y axis limits = 0.00 to 10.00. Plot as line is selected in the Display Wizard and the Overlay Mode turned on.

It is recommended to print this Workroom document and use it as a reference during the activity.

Occasionally chemists must calculate the percentage composition of a compound. That is the percentage by mass contributed by each element in the substance. For example, in order to verify the purity of a compound we may wish to compare the calculated composition of a substance with that found experimentally. Calculating percentage compositions is a straightforward matter if the chemical formula is known.
 
In this experiment you will determine the percentage of sugar in different types of chewing gum. You will then compare your results with the accepted percentage of sugar in each type of chewing gum.

Warning: You will be placing the gum onto the wrapper that has been placed on the pan of the balance. If the gum should come in contact with any lab surface other than the wrapper, you must throw the gum away and start over. Also if you are handling lab equipment be sure to wash your hands before transferring the gum to and from your mouth.

• 0.01g resolution electronic balance (Ohaus Scout SR2020, Ohaus Navigator N02120, or N04120, or equivalent.)
• RS232 Interface Cable (Ohaus Balance to IBM PC cable AS017-09, or equivalent.)
• Several brands of chewing gum

1. Check that the balance is properly connected to the computer through the RS232 interface cable.
2. Insure that the balance is in the grams mode, (g). If needed press the Mode or Units button to set balance to the correct weighing mode.
3. Launch the MassTracker program and make sure your balance and computer are communicating properly. If enabled the Toolbar "Test Mode" button can be used to verify real time communication.
4. Remove the gum from its wrapper, flatten the wrapper out and place it on the pan of the balance.
5. Press the Zero/On button on the balance to tare the mass of the wrapper and determine if the balance is working properly. The display should read zero.
6. Place your sample of chewing gum onto the wrapper. It should measure between 4 and 10 grams.
7. You are now ready to collect the data. Click the Start/Stop arrow in the lower left corner of the MassTracker screen.
8. The first mass reading will be the mass of the gum before chewing. With the gum on the balance pan, move the cursor to any place on the graph and left click the mouse. Notice the mass is recorded in the data table.
9. Place the gum in your mouth and chew vigorously for one minute.
10. Take the gum out of your mouth and place it on the pan of the balance on the wrapper.
11. Left click the cursor on the graph to record the new mass of the gum.
12. Repeat steps 9 through 11 for four more readings. You should have a total of six readings including the initial measurement before chewing.
13. After you take the last reading, click the Start/Stop button to end recording.
14. Repeat this procedure for at least two different brands of chewing gum. Using the overlay mode you can log all trials on the same graph.
15. Title your graph and label each trial with the type of gum that you used. (To edit trial names hold down the shift key and click on the trial name listed above each data value box.) Print the data table and graph when you are finished

1. What is the percent composition of sugar in each brand of gum that you chewed?
   
2. Look on the package and determine the percent composition from the nutritional data for a single piece of gum.
3. Compile the class data and compare the class average to the percentage composition from the nutritional data