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Enriched Biology
Chemical Reactions Lab
Name________________________Per____ Date_________
Introduction:
Energy takes many forms: heat, light, chemical, and mechanical. Plants rely on light energy for
photosynthesis to make sugar. Both plants and animals use chemical energy in sugars to
function. Chemical reactions can release or absorb energy. Photosynthesis absorbs light
energy, and cellular respiration releases energy.
Purpose:
In this lab, you will determine if a specific chemical reaction is releasing or absorbing energy.
You will measure the temperature of the reaction. Exothermic reactions release energy.
Endothermic reactions absorb energy. If it’s an exothermic reaction, the temperature will
_______________. If it’s endothermic reaction, the temperature will _________________.
The two reactions will be
Baking Soda + Vinegar  Sodium acetate + Carbonic acid
Carbonic Acid  Carbon dioxide + water
Calcium Chloride + Water  Calcium Oxide + Hydrochloric Acid
Materials:
(2) 250 ml beaker
Baking soda
Quick Check Thermometer
Calcium chloride
vinegar
stirring rod
water
stop watch
Procedure:
Create the Set-up:
1. Place the Quick Check temperature sensor-ring stand setup on the lab table.
2. Obtain two 250ml beakers. Label one CaCl2 and the other beaker Baking Soda using
label tape. Place the tap on the upper area of the beaker.
3. Fill the Baking Soda beaker with 100 ml of vinegar. Carefully place the Baking Soda
beaker underneath the temperature sensor. Lower the temperature sensor so that the tip
of the thermometer is beneath the surface of the vinegar. Allow the thermometer to sit in
the vinegar for several minutes. Then record the temperature on the table.
4. Proceed to the balance station. Using a spatula and weigh boat, measure out 2 grams of
baking soda. Place the weigh boat on the balance. Wait for its mass, and then press the
‘zero’ button to tear the mass. Now you will see a reading of 0.00 grams.
5. Carefully add baking soda to the weigh boat until it reads 2 grams. Remove the weigh
boat and from the balance. Return to your beaker-thermometer set-up.
6. Re-check the temperature of the vinegar. Be sure that you can easily read the
temperature because you will be trying to take a temperature reading every 20 seconds.
This will require team work. One person reads the thermometer and the other reads the
stop watch and records. Determine who will do each job.
Start the Baking Soda and Vinegar Trial:
7. Simultaneously add the 2 grams of baking soda to the beaker of vinegar and start the
timer. Record temperature every 20 seconds for 3 minutes. Use the stirring rod to stir
the solution. Do not hit the sides of the beaker or thermometer.
8. After the 3 minutes are up, raise the thermometer and carefully remove the beaker from
underneath the thermometer. Empty the beaker in the sink and place the dirty beaker in
appropriate place.
9. Use a damp paper towel to wipe off the thermometer. Complete Data Table.
10. Proceed to run the Calcium Chloride reaction using the technique as for the Baking Soda
reaction.
Setup Calcium Chloride Reaction:
11. Fill beaker with 100ml of tap water. Place beaker under the thermometer. Lower the
thermometer into the water. Allow the thermometer to sit in the water for several
minutes.
12. Measure out 15 grams calcium chloride on a weigh boat using the balance. Carefully,
carry it back to the lab table.
Run the Calcium Chloride Reaction (Goggles Must Be Worn! Zero for Lab if not worn)
13. Determine who will read the thermometer and who will read the stop watch. Record the
initial temperature of the water in the Table.
14. Simultaneously add the 15 grams of calcium chloride to the beaker of water and start the
timer. Record temperature every 20 seconds for 3 minutes. Use the stirring rod to stir
the solution. Do not hit the sides of the beaker or thermometer.
WARNING: DO NOT TOUCH THE BEAKER. DO NOT PUT FACE IN THE BEAKER.
15. After the 3 minutes are up, allow the calcium chloride beaker solution to sit for 5 minutes.
While waiting, complete the data tables.
16. Read board for calcium chloride and general cleanup.
Data Table 1 Title ___________________________________________________________
Time (seconds)
Temp (oC) Baking Temp (oC) Calcium
Soda + Vinegar
chloride + water
0
20
40
60
80
100
120
140
160
180
Data Table 2 Title ___________________________________________________________
Reaction
Initial Temp
(oC)
Final Temp (oC)
Change Temp
(oC)
Heat Release or
Absorbed ?
Baking Soda +
Vinegar
Calcium chloride +
Water
Analysis: Identify which reaction was exothermic and endothermic using data.
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