Download Physical vs

Student Names: ___________________________________________________________________________
Mrs. Lee – 8th Grade Physical Science
Date: _________
Period: ________
Physical vs. Chemical Change Lab
If it’s a Chemical Change, is it Endothermic or Exothermic?
1) What is the definition of Physical Change?: ________________________________________________________________________
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2) Give an example of a Physical Change: ____________________________________________________________________________
3) What is the definition of a Chemical Change?: ______________________________________________________________________
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4) Give an example of a Chemical Change: ___________________________________________________________________________
5) What is the definition of Endothermic Reaction?: ____________________________________________________________________
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6) Give an example of an Endothermic Reaction: ______________________________________________________________________
7) What is the definition of Exothermic Reaction?: _____________________________________________________________________
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8) Give an example of an Exothermic Reaction: _______________________________________________________________________
Problem:
How can I determine if a change in matter is a physical or chemical change? If it is a chemical change, how do I determine if it’s an
endothermic or exothermic reaction?
Background:
 Physical change does not make any substance in the matter into a different substance. It only alters the form or appearance.
 Chemical change produces one or more new substances. At the same time, it can alter the form or appearance.
 Yeast (Saccharomyces cerevisiae) converts carbohydrates to carbon dioxide (used in baking) & alcohols (used in alcoholic
beverages like wine & beer). It has been used in baking & fermentation for over 4,000 years. Also, for biologists, it is one of the
most thoroughly researched eukaryotic microorganisms. The simplicity & importance of yeasts lies in the fact that they are
unicellular organisms with a rather high variety of useful enzymes. It was the first eukaryotic organism to have its complete
genome (12 million base pairs) unraveled by the Genome Project.
 Hydrogen Peroxide (H2O2) bubbles when you pour it onto a cut because there is something in your body that catalyzes (speeds
up) the decomposition of H2O2 into H2O. In this experiment, the addition of yeast to hydrogen peroxide catalyzes the reaction &
creates the production of bubbles of oxygen gas along with foam: 2H2O2  2H2O + O2 (g).
 Endothermic Reactions: Reactants + Energy = Products, Exothermic Reactions: Reactants + Energy = Products
HYPOTHESIS
1) If put 1 teaspoon of
yeast in 50 mL of
water, then the
reaction is a ….
PREDICTION
a) Physical or
Chemical
Change?
b) Endothermic
or Exothermic or
Neither?
2) If put 1 teaspoon of
yeast in 50 mL of
Hydrogen Peroxide,
then the reaction is a
…
3) If put 1 teaspoon of
baking soda into 50
mL of Vinegar, then
the reaction is a…
a) Physical or
Chemical
Change?
b) Endothermic
or Exothermic or
Neither?
a) Physical or
Chemical
Change?
b) Endothermic
or Exothermic or
Neither?
RECORD
OBSERVATIONS
PICTURE
HYPOTHESIS
CORRECT?
WHY OR WHY
NOT?
Observations:
Lowest Temp:
Highest Temp:
Observations:
Lowest Temp:
Highest Temp:
Observations:
Lowest Temp:
FINAL
RESULTS
a) Physical or
Chemical Change?
b) Endothermic or
Exothermic or
Neither?
a) Physical or
Chemical Change?
b) Endothermic or
Exothermic or
Neither?
a) Physical or
Chemical Change?
b) Endothermic or
Exothermic or
Neither?
Highest Temp:
Conclusion:
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Interesting websites to check out: http://www.coolscience.org/CoolScience/KidScientists/h2o2.htm
http://www.hometrainingtools.com/a/cool-chemistry-and-weird-reactions
http://www.education.com/science-fair/article/chemical-reations-absorb-release-energy/