Reaction in a Bag- Endothermic or Exothermic?
Name:
Driving Question: Is the reaction in the bag endothermic or exothermic?
Background Information
A chemical reaction is the change of one substance into another substance. The new substance
will have properties different from that of original substance. For example, sodium can combine
with chlorine gas to form table salt. Table salt has different properties than both sodium and
chlorine.
There are two types of chemical reactions: Exothermic and Endothermic reactions.
An Exothermic reaction is a chemical reaction that releases energy. Because energy is released,
exothermic reactions produce heat and sometimes even explosions.
General Exothermic chemical equation:
Reactants  Products + Energy
An Endothermic reaction is a chemical reaction that absorbs energy from its surroundings.
Because energy is taken from the surrounding, a decrease in temperature occurs.
General Endothermic chemical equation
Reactants + Energy  Products
Identify these reactions as Endothermic or Exothermic:
Reaction
Melting ice cubes
Evaporating liquid water
Condensation of rain from water vapor
A candle flame
Baking Bread
Photosynthesis
Respiration
forming ion pairs
separating ion pairs
cooking an egg
Endothermic
Exothermic
Reaction in a Bag- Endothermic or Exothermic?
Let’s Do it!
Safety Measures:
What will you need for this experiment?
-
1 dropper of Phenol red
Graduated cylinder
Plastic spoon
Plastic bag
Granular calcium chloride (CaCl2)
Baking Soda (NaHCO3)
Temperature probe
Gloves
-
Wear glasses and gloves while performing
the practical
Calcium chloride if not handled properly
could lead to serious eye irritation
If it happens, contact the responsible
person in the class immediately.
After performing the practical, make sure
to dispose the contents of the bag in the
sink and then dumping the bag.
Assumption:
What is your assumption about the type of reaction based on the materials used?
Follow the procedure and record your observation!
Procedure
1. Add one dropper full of phenol red in your
bag.
*Caution: Phenol red stains*
2. Add 20ml of water to the plastic bag
3. Seal the bag and move back and forth to
mix it.
*Tip: You can also use your finger to knead
the bag from outside*
4. Record your observation/evidence
*Make sure to record the general
temperature of the bag*
5. Open the bag and add a small spoonful of
calcium chloride.
6. Seal and follow the same procedure as you
did in step 3 to mix the contents.
7. Record observations/evidence
*Make sure to record the general
temperature of the bag*
8. Open the bag and add a small spoonful of
baking soda.
9. Seal and mix the contents again.
10. Record your observation/evidence.
Observation/Evidence
Reaction in a Bag- Endothermic or Exothermic?
Answer the following questions.
1. Which steps of the procedure produced a chemical reaction? How did you know a chemical
reaction was taking place?
2. What is the difference between exothermic and endothermic reactions?
3. In which part of the experiment did an exothermic reaction happen? Which component is
responsible for releasing heat? Explain.
4. In which part of the experiment did an endothermic reaction take place? Which component
is responsible for absorbing heat? Explain.
5. How can you relate this experiment to the real world? Hint: think about a possible product
that might utilize the principles of endothermic and exothermic reactions?
Reaction in a Bag- Endothermic or Exothermic?