Endothermic & Exothermic Reactions
Problem: Determine whether a chemical reaction is endothermic or exothermic.
Predict: Will the following reactions lose or gain heat?
Baking soda & vinegar ______
Potato & hydrogen peroxide ______
Liver & hydrogen peroxide ______
Materials: TI graphing calculator loaded with the Vernier CHEMBIO program CBL unit with temperature sensor
3% hydrogen peroxide
Baking soda
Vinegar
Potato
Liver
Test tubes
Forceps
Thermometer
Spoon
Graduated cylinder
GOGGLES
Procedure:1. Prepare the graphing calculator and CBL:
(a) Put the temperature sensor in channel 1 (CH1) of the CBL unit
(b) Use the link cable to connect the calculator to the CBL unit. Plug the cable into the bottom of both the calculator and the CBL.
(c) Turn the calculator on.
(d) Turn the CBL on. The CBL must be ON as you are setting up the calculator.
(e) Press the PRGM key on the calculator.
(f) Select 1:CHEMBIO.
(g) Press ENTER.
(h) Press ENTER until you come to the ***MAIN MENU***
(i) Select 1:SET UP PROBES.
(j) Enter 1 after ENTER NUMBER OF PROBES. Press ENTER.
(k) Select 1:TEMPERATURE.
(l) Enter 1 after ENTER CHANNEL NUMBER. Press ENTER.
(m) Back at the ***MAIN MENU*** Select 2:COLLECT DATA
(n) At the DATA COLLECTION menu, select 2:TIME GRAPH
(o) Enter 1 at ENTER TIME BETWEEN SAMPLES IN SECONDS:. This tells the CBL to take the temperature every second. Press ENTER.
(p) Enter 15 at ENTER NUMBER OF SAMPLES:. This tells the CBL to collect take the temperature 15 times. Press ENTER.
(q) Your calculator screen now reads: SAMPLE TIME: 1 S SAMPLES 15 EXPERIMENT LENGTH 15.00 S If it doesn’t, press 2nd, press QUIT to go back to set up again. Press ENTER.
(r) At the **CONTINUE** screen, select 1:USE TIME SETUP. Press ENTER.
(s) Enter 0 at SET Y-AXIS Ymin=? This tells the CBL to begin the y-axis of the graph at 0 degrees celsius.
(t) Enter 50 at Ymax=? This tells the CBL to end the y-axis of the graph at 50 degrees celsius.
(u) Enter 1 at Yscl=? This tells the CBL to measure the temperature in increments of 1 on the y-axis. Press ENTER.
(v) The calculator reads: PRESS [ENTER] TO BEGIN COLLECTING DATA. DO NOT PRESS ENTER YET! You are ready to set up the rest of the experiment:
2. Put on your goggles.
3. Put ½ spoon of baking soda in the bottom of a test tube.
4. Use the thermometer to find the starting temperature of the liquid. Record this in your data chart.
5. Put the temperature sensor all the way into the test tube.
6. Measure 5ml of vinegar into the graduated cylinder.
7. Make sure the CBL and the calculator are both ON.
8. ¨This takes two people¨ One person pour the vinegar into the test with the baking soda at the same time another presses ENTER on the calculator.
9. You will see your graph being created on the screen of the calculator and the temperature being recorded on the screen of the CBL.
10. When the data collection is done, the calculator screen will read: TIME IN L1 IN L2 Press ENTER. You will see a time graph of your experiment. The temperature will be on the y-axis, the time it took will be on the x-axis.
11. Press TRACE and the arrow keys to see the exact temperature at each time.
12. To repeat the experiment, Press STAT, press ENTER, Select 2:YES. If you do not want to repeat, select 1:NO, press ENTER.
13. At the ***MAIN MENU*** press 4:VIEW DATA.
14. Press STAT, Select 1:EDIT, press ENTER. You will see lists that contain your data. Time is in L1, Temperature is in L2.
15. Record this data in a chart.
16. Repeat steps 1 – 15 using potato and hydrogen peroxide.
17. Repeat steps 1 – 15 liver and hydrogen peroxide.
DATA:
Temperature in Seconds
Reaction
/ Start T / 1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 / 10 / 11 / 12 / 13 / 14 / 15Baking soda & vineger
Hydrogen peroxide & potato
Hydrogen peroxide & liver
Analysis & Conclusions:
1. Which reactions were exothermic? Give evidence to support your answer.
2. Which were endothermic? Give evidence to support your answer.
3. What advantage does technology provide in collecting data. Give
evidence to support your answer.
This activity addresses TEKS 8.10c – identify and demonstrate that loss or gain of heat energy occurs during exothermic and endothermic chemical reactions
TI – 83 / 73