Chemical Reactions Worksheet

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Chemical Reactions Worksheet Powered By Docstoc
					Queensland Science 1
Experiment 4.2: Chemical Reactions That Go Cold
You may either make use of a temperature probe attached to a CBL and a TI -82 or TI-83
calculator to record the temperature, or you may record the temperature drop with a
thermometer.

Method:
1. Measure 100 mL of water (at about room temperature) with a measuring cylinder. Pour
this into a beaker.

2. Measure an amount of ‘hypo’ (sodium thiosulfate). Record the mass. (Suggested masses
for class investigation are up to about 15gm in this volume of water.)

3. Measure the temperature of the water with either a CBL™ temperature probe using the
CBL ™ program ‘Temp’, or a thermometer. Wait until the temperature is steady before
proceeding to the next step.

4. Record the temperature of the water. (If you are using a thermometer, try to record the
temperature to one decimal place.)

5. Add the hypo to the water, stirring gently to help it dissolve. Watch the temperature
closely and record the lowest temperature reached.

6. Either share your data with the rest of the class or repeat steps 1 to 5 for four other
different masses of hypo.

7. Go to the 'Exp 4.2' tab in this spreadsheet.

8. Enter your name and the date of the experiment.

9. Enter your data in the table.
• The graph will develop as you enter your data.
• Click on the chart. Draw in a line of best fit through your points by selecting ‘Chart’ → ’Add
Trendline’ and then choose the most appropriate line.

10. Print out the page with both the table of temperatures and the graph, and paste it into
your book.

11. What can you conclude about the experiment you have just done?




Note to teachers on CBL:

This experiment requires the measurement of temperature. This may be done either with a thermometer or with
one or two temperature probes connected to a CBL™. Either method will enable students to gather suitable data.

CBL™ programs may be downloaded freely from the Vernier Software & Technology website at:
                            http://www.vernier.com/legacy/cbl/progs.html
The ‘Physics’ package contains a set of program files for different purposes, and can be used with TI-
82 and TI-83 calculators. This package, which contains a number of different program files, includes
the program ‘TEMP’ which is used in some of these activities.
You will need to visit the website to choose the most appropriate version of this file for your school’s needs and
equipment (that is, Windows or Macintosh? TI-82 or TI-83?). Teachers inexperienced in CBL™ equipment are
advised to download the free manual CBL™ Made Easy! from:
                                 http://www.vernier.com/legacy/cbl/easy.html
hypo’ (sodium thiosulfate). Record the mass. (Suggested masses




in a line of best fit through your points by selecting ‘Chart’ → ’Add
                            Name:                                                Date:

                                      Mass of hypo         Initial         Lowest         Temperature
                        Trial            (gm)         temperature (oC) temperature (oC)    drop (oC)
                          1                                                                    0
                          2                                                                    0
                          3                                                                    0
                          4                                                                    0
                          5                                                                    0


                                          Exp 4.2: Chemical reactions that go cold.
                                  1
Temperature drop (oC)




                                0.8
                                0.6
                                0.4
                                0.2
                                  0
                                      0                             0.5                             1
                                                           Mass of hypo (gm)

				
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