February 15, 2011 Class Period 3 Clicker Number 24
Chemical And Physical Change Experiment
What is the difference between a chemical change and a physical change? What are some of the
characteristics of a physical change as opposed to a chemical change? What are some indicators that distinguish a
physical change from a chemical change?
II. Background Information:
Understanding the properties of matter is an essential tool to understanding and predicting reactions.
This experiment demonstrates the physical and chemical properties of elements, compounds and mixtures and
illustrates their interactions with one another. Physical and chemical interactions are taking place every day. The
observations made in this lab guide understanding of those reactions taking place in the environment and in the
Indicators of Chemical reactions taking place can be observed through color changes, gas bubbles
forming, precipitates forming, temperature changes and the variable dispersion of light2. The dispersion of light
through a substance is also know as the Tyndall effect and can be measured to tell the difference between a
homogeneous or heterogeneous mixture.
A physical change is manifest by the lack of a color change or gas bubbles, no precipitates forming, no
temperature difference and no discernable change in the dispersion of light through the mixture that was not a
property of either of the two being combined in the mixture. A change in number of pieces for instance, one piece
of paper being divided into two, or a change in size, a powder absorbing a fluid might be examples of a physical
change having occurred.
The following is a table of predictions for the 4 parts of the lab:
Test Type of Change
Part 1: KI and Pb(NO3)2 Physical
Part 3: Sodium polyacrylate and water Physical
Part 7: Mg metal and acid Chemical
Part 8: Gatorade® and water Physical
IV. Test the Hypothesis
8 drops of aqueous KI were placed in a clean test tube. To it about 8 drops of Pb(NO3)2 was
added. Observations were recorded. The test tube was cleaned well with water.
A scoopula was used to obtain a small serving of sodium polyacrylate, which was placed in an
evaporating dish. An excess of deionized water was added to the evaporating dish. Observations were recorded
and per instructions the products were discarded in the trash.
A small piece of magnesium metal was obtained and placed in a cleaned test tube. Three drops
of solution B were added and observations were recorded. The metal was discarded in the trash.
A small scoop of Gatorade® powder was added to a clean test tube and a few drops of water were
added to the same tube. Results were recorded and the solution was discarded down the drain.
Table #1: Physical Chemical Change Results
Test Indicators Observations Type of
Part 1: KI and Pb(NO3)2 Color, precipitate A yellow precipitate formed Chemical
Part 3: Sodium polyacrylate Swelling The sodium polyacrylate got bigger Physical
and water absorbing the water
Part 7: Mg metal and acid Bubbles and The metal bubbled and gave off some Chemical
Part *: Gatorade® and water No change The two mixed well with no chemical Physical
VI. Draw Conclusions:
This experiment evaluated the physical and chemical changes associated with differing compounds, elements and
mixtures. Through this experiment it became clear when a chemical reaction was taking place. The color changed in part 1
with the formation of a precipitate. In part 3 there were bubbles as the chemical indicator. While the physical changes were
not as obvious, the lack of the chemical indicators provided the necessary clues as to which reaction was taking place.
This experiment illustrated the applicability of the indicators in accurately discerning physical changes from
chemical changes and provides a method in determining whether these changes exist without testing each and every sample.
This experiment investigated physical and chemical changes associated with KI and Pb(NO 3)2, sodium
polyacrylate and water, magnesium metal and acid and Gatorade ® with water. It was found that KI in Pb(NO3)2
and magnesium metal in acid were chemical changes whereas the Gatorade® with water and sodium polyacrylate
in water were physical changes