East High Chemistry Group
Name ______Period ______
Chapter 6 –Cool Chemistry Show
Activity 5 Outline: Chemical Energy (page 468-476)
What do you see?
What do you think?
Investigate (pgs 468-469) Write your answers in the spaces provided.
1. To make a cold pack, place a scoop of ammonium nitrate in a quart-size resealable plastic bag. Add 10 mL of water to the bag and seal.
a) Record your observations.
______
In an endothermic chemical reaction, energy in the form of heat is absorbed in the process. In an exothermic reaction, energy in the form of heat is given off in the process.
b) Was the cold pack an example of an exothermic or endothermic chemical reaction? ______
2. Make a hot pack by placing a scoop of calcium chloride in a quart-size, resealable plastic bag. Add 10 mL of water to the bag and seal.
a) Record your observations.
______
b) Was the reaction exothermic (heat generating) or endothermic (heat absorbing)? ______
3. Your teacher will demonstrate a reaction between barium hydroxide and ammonium thiocyanate.
What is the chemical formula for barium hydroxide? ______
What is the chemical formula for ammonium thiocyanate? ______
a) Record your observations of the demonstration.
______
b) Was the reaction exothermic (heat generating) or endothermic (heat absorbing)? ______
ChemTalk pg. 470-473
Checking Up pg. 473
1. Describe an endothermic reaction.
______
2. Describe an exothermic reaction.
______
3. Explain whether each of the following is endothermic or exothermic. Give a reason for your answer.
a) chemical bond breaking
______
b) chemical bond forming
______
4. Distinguish between heat and temperature.
______
What do you think now?
Chem To Go pg. 475
Chem To Go pg. 475
1. Identify the following changes as endothermic or exothermic. (Ask yourself if the reaction requires the addition of heat energy to occur or does it release energy in the form of heat.)
a) Melting ice ______
b) lighting a match ______
c) dry ice subliming into carbon dioxide gas ______
d) frying an egg ______
e) burning gasoline ______
f) explosion of hydrogen gas when it reacts with oxygen gas ______
6. Given the reaction:
S(s) + O2(g) → SO2(g) + energy
Which diagram on page 475 of your textbook best represents the potential energy changes for this reaction? ______
Reflection:
What did you learn from this activity?
How might you use this in your chemistry show?
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