PHYSICAL SCIENCE LAB 100 – THERMAL REACTIONS
Materials: Steel wool, thermometer, jar or 100ml beaker, vinegar, twisties
Introduction: Chemical reactions occur every day all around us. A chemical reaction is a process where
one type of substance is chemically converted to another substance. All chemical reactions involve the
formation or destruction of bonds between atoms. Chemical reactions include the rusting of iron and the
digestion of food, for example. Many chemical reactions are thermal, i.e., they either absorb or release
energy in the form of heat. The fire in your fireplace is a type of exothermic chemical reaction, where
heat is released.
Objective: To demonstrate a common thermal reaction that occurs at room temperature.
Procedure:
1. Insert the thermometer through the hole in the Styrofoam lid. Put the thermometer in the beaker with
the bulb of the thermometer off the bottom of the beaker. You will have to tape the thermometer to the
lid so that it doesn’t touch the bottom of the beaker.
2. Wait about 5 minutes and record the temperature reading of the thermometer.
3. Soak a piece of steel wool in vinegar for one minute.
4. Squeeze the vinegar out of the steel wool pad and wrap it around the bulb of the thermometer. Secure
with one or two twisties.
5. Remove the thermometer from the jar.
6. Place the thermometer and steel wool back into the jar and close the lid. Again, make sure the
thermometer doesn’t touch the bottom of the beaker.
7. Wait 5 minutes.
8. Read the temperature of the thermometer again and record the reading.
Questions:
1. How did the temperature in step 2 compare to the temperature in step 8 of the procedure?
2.
Is this reaction EXO-thermic or ENDO-thermic? How do you know?
3. Do you observe any change in the color of the steel wool?
3. Describe what you think is happening in the above experiment.
4. What do you think the role of the vinegar is in this chemical reaction?