Hot Solutions Lab
Name __________________
Block ___________
Many interactions between chemicals may release or absorb energy. Interactions that release
energy are called exothermic. Some interactions absorb energy and are called endothermic. You
will study these interactions by mixing calcium chloride (CaCl2) with water (H2O).
Pre-lab questions:
After viewing the demonstration by your teacher answer the following questions:
1. Did the reaction appear to result in an endothermic (absorption of energy) or an
exothermic interaction (release of energy)?
2. The interaction between calcium chloride and water involves the process of dissolving
(absorbs energy), and the process of forming a hydrate which results as water molecules
are hydrogen bonded to the other atoms (releases energy). According to what you have
witnessed with calcium chloride and water, which of these two processes has a greater
affect on energy change in the cup of Calcium Chloride mixed with water? Explain your
choice:
3. What would happen if more calcium chloride were added to the water? State a
hypothesis using and IF… THEN... statement. See L4.
Hypothesis:
Another objective of this experiment is for you to become familiar with using the DataMate datacollection program on the TI Graphing Calculator. In this experiment, you will use the program
to collect and display data as a graph or list, to examine your experimental data values on a
graph, and to create graphs and data tables from the information gathered.
MATERIALS
LabPro or CBL 2 interface
TI Graphing Calculator
DataMate program
Temperature Probe
50-mL graduated cylinder
Pan Balance
Styrofoam cup
250-mL beaker
Chemical Calcium Chloride (CaCl2) –
white solid
Tap water
Measuring paper or boats
Scoop
SAFETY
1. Calcium Chloride is an irritant. Harmful if swallowed. Avoid contact with eyes, skin and
clothing. Wash thoroughly after handling. Avoid breathing the dust.
2. First Aid: (poison) If swallowed, if conscious, wash mouth with water. Induce vomiting by
giving large amounts of water to drink. If necessary have victim stroke back of throat with
finger. Get medical attention immediately. Never give anything by mouth to an unconscious
person.
3. Eyes: In case of eye contact, immediately flush eyes with plenty of water for at least 15
minutes. Get prompt medical attention.
PROCEDURE
1. Obtain and wear goggles and an apron. Keep your Labpro system clear of spraying water
please.
2. Do not press any buttons on the Lab pro, unless directed to by your teacher. Plug the
Temperature Probe into Channel 1 of the LabPro. Use the black link cable to connect the TI
Graphing Calculator to the Labpro interface. Firmly press in the cable ends. This may be
done already for you. Plug the AC adaptor into the Labpro, then into the electrical outlet.
You should see the lights flash on your Labpro, and hear beeping sounds.
3. Turn on the calculator and follow these steps to start the DATAMATE program.
Press
, then press the number that precedes the DATAMATE program, or arrow key
down to DATAMATE and press Enter. If you aren’t at the main screen you may need to
press Enter again. You are now at the main screen of the program.
4. Follow the steps below (a-e) to set up the calculator and interface for the Temperature Probe.
a. Select SETUP from the main screen.
b. If the calculator displays a Temperature Probe in CH 1, proceed directly to Step 5. If it
does not, continue to set up your sensor manually.
c. Press
to select CH 1.
d. Select TEMPERATURE from the SELECT SENSOR menu.
e. Select the Stainless Steel Temperature Probe (in °C) from the TEMPERATURE menu. Press
the number or use the arrow keys and enter key.
5. Follow the steps below (a-i) to set up the data-collection mode.
Press
to calibrate your temperature probe. Don’t forget this step!
To select MODE, press
once and press
.
Select TIME GRAPH from the SELECT MODE menu.
Select CHANGE TIME SETTINGS from the TIME GRAPH SETTINGS menu.
Enter “3” as the time between samples in seconds. Press
.
Enter “40” as the number of samples. The length of the data collection will be 2 minutes
(3 times 40 = 120). Press
.
g. Select OK to return to the setup screen.
h. Select OK again to return to the main screen.
i. Don’t push any more buttons at this time. If your screen goes blank while setting up the
next steps just hit the “ON” button.
a.
b.
c.
d.
e.
f.
6. Now start setting up your system by placing a Styrofoam cup into a 250-mL beaker as shown
in Figure 1 on the first page. Measure out 50 mL of water in a graduated cylinder and place
into the Styrofoam cup. Place the Temperature Probe into the water and leave it there for
now.
Figure 1
7. Weigh out your assigned amount of solid Calcium Chloride (CaCl2) into a weighing boat by
first setting your balance to your assigned amount using the sliders, place your boat on the
left pan, then fill the boat a little at a time with CaCl2 until the balance needle reaches the
middle again. DO NOT put the solid Calcium Chloride into the water yet. We will not take
into consideration the weight of the boat this time. (Ask the teacher if you are not sure about
this part!)
8. You are now ready to begin collecting data. Follow the steps below (a-e) to start collection.
a. Make sure your temperature probe in the water in your Styrofoam cup. Do not pour the
Calcium Chloride in yet.
b. Read this entire direction first before pressing START. In this step you will select
START on the main screen and after about 15 seconds have elapsed (seen as 5 plotted dots
on the graph on the calculator screen), add the calcium chloride to the water. Gently stir
the solution with the Temperature Probe to ensure good mixing. Do not remove the
temperature probe from the solution until data collection is finished. A real-time graph of
temperature vs. time will be displayed on the calculator screen during data collection, and
will stop on its own.
c. OK NOW select START and complete step b above.
d. Temperature readings (in °C) can also be monitored in the upper-right corner of the graph.
e. Data collection will stop after 2 minutes, and a graph of temperature vs. time will be
displayed.
9. Examine your graph. Use the
or
keys to examine the data points along the
displayed curve of temperature vs. time. As you move the cursor right or left, the time (X)
and temperature (Y) values of each data point are displayed below the graph. Determine the
initial starting (lowest or minimum) temperature, t1, and final (highest or maximum)
temperature, t2. Record these temperature values in the individual data table on the
following page (round to the nearest 0.1°C), then calculate and record the temperature
change, t, by subtracting the initial temperature, t1, from the final temperature, t2. Use the
following formula t = t2 – t1. The delta symbol or triangle means “change in.” Return to
step 10 when finished with the first column of the table.
INDIVIDUAL DATA TABLE
Assigned Level: _______ grams CaCl2
O grams of CaCl2
Trial # ________
Trial # ________
Final temperature (highest), t2
°C
°C
Initial temperature (lowest), t1
°C
°C
°C
°C
Temperature change, (t
= t 2 – t1 )
10. Rinse the temperature probe with water and dry carefully. Dispose of the liquid solution in
your cup into the large jar at the end of the lab tables.
11. Press enter to return to the main screen. Repeat steps 6-10 again but this time do not add any
Calcium Chloride to the water. You will be testing only the temperature change in plain
water over a 2 minute period. Thus you will not need to measure out any Calcium chloride
when you repeat these steps. This will serve as your control group to compare to your
experimental groups with Calcium Chloride.
12. At this time please clean up your lab area and return all equipment to their storage areas if
instructed to do so.
13. Now fill in your data into the correct levels and trials on the CLASS DATA TABLE on the
board at the front of the room.
14. Once all lab groups have entered their trial’s data onto the CLASS DATA TABLE and all
errors have been dealt with fill in your CLASS DATA TABLE on your Lab Write-up page.
At this time also calculate and record the MEAN (class average) for change in temperature of
water (degrees Celsius). For the zero grams of Calcium Chloride you may have to average
more than 4 values. Add all the data and divide by the number of trials done. Then calculate
RANGE.
15. Go back and complete the rest of the Write-up starting at the beginning with Title and
working up through Procedures using information in this lab handout and from your lab
experience. For procedures write a simple procedure for the experiment as if we used a
regular thermometer, leaving out all the details on how to use and set-up the calculator. Also
leave out how to use the pan balance. It should be like our Weathering lab procedures written
as if your group completed all trials and levels yourself with a statement for repeating trials
and for repeating levels. Then…
16. Using the rules for graphing, complete the graph section of your Lab Write-up page. Decide
which axis the I.V. and D.V. should go on, and what type of graph it should be. Calculate the
increments using the formula from L4. Graph the MEANS of the Class Data ONLY. Plot
Average Change in Water Temperature (Celsius) vs. Amount of CaCl2 (grams). Then…
17. Complete the Results Statement and the Conclusion (questions #1-7). The formats for the
result statement and the conclusion questions are located in your L4 Experimental Design
Reference packet towards the end.
18. Check the completeness of your lab report by filling out the rubric and calculating your score.
Only fill in one of the graph sections on the rubric. Well done. You are finished! Hand the
entire lab into the IN BOX.
Hot Solutions Lab Write-up Form
Name __________________
Block ______________
Title:
Hypothesis:
Experimental Design:
I.V. (must be quantified):
Levels
Trials
D.V. (must be quantified)
Constants:
1)
2)
3)
4)
5)
6)
Control: ______________________________
Materials:
1.
Safety:
1.
Procedures:
1.
Class Data Table Title: __________________________________________________
Graph Title: ________________________________________________________
Results Statement:
Conclusion: (All 7 conclusion questions including #8 real life or career applications - see
Exp. Design Reference Packet)
1.
2.
3.
4.
5.
6.
7.
8.