Observing Changes in Matter
Chemistry
Name:
Date:
Per:
My role(s) for this activity is/are:
Directions: Work as a group to reach a consensus on each question. Write all answers in complete
sentences, and use supporting evidence from the model whenever possible. Stop when you reach a stop
sign and check in with your instructor. If you finish early, use remaining time to fill in your notes organizer.
Why?
Observing Changes in Matter
What evidence can be used to determine if a change is physical or chemical?
Matter is anything that has mass and takes up space. Everything around us is made up of matter. Matter
can undergo two kinds of changes: physical, and chemical. The purpose of this investigation is to develop a
solid definition of physical and chemical change, and to develop a solid list of evidence that would indicate
which type of change has occurred.
1. Complete the following lab activity:
For each station you visit, read the procedure. Make observations about what the substances before
you carry out the procedure. Develop a prediction about what you think will happen. Carry out the
procedure and record a detailed set of observations.
Station 1
Procedure
Light a candle inside a beaker. Observe for a few
minutes and record. Blow the candle out.
Prediction
Station 2
Procedure
Grind a piece of chalk with a mortar and pestle.
Observe. Place the powered chalk in a small beaker.
Add 10mL of acetic acid to the beaker with the
chalk. Observe and record. Rinse the beaker with
tap water.
Prediction
Observations Before
Observations After
Observations Before
Observations After
Station 3
Procedure
Place a spoonful of starch into a 250mL beaker that
contains 50mL of water. Stir. Add 2 drops of iodine.
Observe and record. Rinse the beaker with tap
water.
Observations Before
Prediction
Observations After
Station 4
Procedure
Place 200mL of water into a 250mL beaker. Drop a
piece of AlkaSeltzer into the water. (just use about
¼ of one, you do not need the whole thing) Observe
and record. Rinse the beaker with tap water.
Observations Before
Prediction
Observations After
Station 5
Procedure
Add a half dropper full of iron(III)nitrate (Fe(NO3)3)
solution to a test tube. Add a half dropper full of
ammonium hydroxide (NH4OH) solution into the
tube. Observe and record. Rinse the test tube with
tap water.
Observations Before
Prediction
Observations After
2
Station 6
Procedure
Add 2 drops of universal indicator to one well of a
well plate. Add 2 drops of dilute hydrochloric acid to
the same well. Note any changes. Add four drops of
dilute sodium hydroxide to the well. Observe and
Record. Rinse the well plate with tap water.
Observations Before
Prediction
Observations After
Station 7
Procedure
Place a spoon full of sodium bicarbonate (NaHCO3)
into a beaker. Place 5 mL of acetic acid (HC2H3O2) in
the beaker. Record observations. Rinse the beaker
with water in the sink.
Observations Before
Prediction
Observations After
Station 8
Procedure
Place a spoonful of salt in a beaker. Place a spoonful
of Kool-Aid in another beaker. Add 100mL of water
to each. Stir and observe. Rinse both beakers with
water.
Observations Before
Prediction
Observations After
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Read This!
Physical changes are changes that alter a substance without changing its composition. An example of a
physical change is cutting a piece of paper in half. Chemical changes are changes in which one or more
substances are being transformed into new substances. Chemical change can also be called chemical
reactions.
2. For each station, discuss in your group which ones you thought were physical changes and which
you thought were chemical changes. Support each of your responses.
A. Station 1-
E. Station 5-
B. Station 2-
F. Station 6-
C. Station 3-
G. Station 7-
D. Station 4-
H. Station 8-
3. Looking back at your reasoning for each of the choices in question 2, develop a list of evidence that
would suggest a physical change is occurring, and a list of evidence that would suggest a chemical
change is occurring. If you feel a piece of evidence belongs in both columns write it in both.
Evidence of Physical Change
Evidence of Chemical Change
4. Are there any pieces of evidence that your team decided belonged in both columns? If
there are, explain why those pieces of evidence could be considered physical in one
instance and chemical in another.
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Read This!
Physical changes are limited to changes that result in a difference in display without changing the
composition. Some common changes include: texture, color, temperature, shape, and change of state.
Chemical changes, on the other hand, are quite different. A chemical change occurs when the substance's
composition is changed. When bonds are broken and new ones are formed a chemical change occurs. The
following are indicators of chemical changes: change in temperature, change in color, noticeable odor,
formation of a precipitate (a solid compound when reacting two solutions), smoke, and formation of
bubbles.
5. Review your initial assessment for whether a physical or chemical change occurred at
each of the lab stations. Do you agree with your original assessment? If not explain why
you have changed your original decision.
6.
A.
B.
C.
D.
E.
Which of the following is a chemical reaction?
Freezing liquid Mercury
Adding yellow to blue to make green
Cutting a piece of paper into two pieces
Dropping a sliced orange into a vat of Sodium Hydroxide
Filling a balloon with natural air
A.
B.
C.
D.
E.
Which of the following is a physical reaction?
Shattering Glass with a baseball
Corroding Metal
Fireworks Exploding
Lighting a match
Baking a cake
A.
B.
C.
D.
E.
Which of the following is a chemical reaction?
Painting a wall blue
A bicycle rusting
Ice cream melting
Scratching a key across a desk
Making a sand castle
A.
B.
C.
D.
E.
Which of the following is a physical reaction?
Frying an egg
Digesting carrots
A computer falling out of a window
Creating ATP in the human body
Dropping a fizzy tablet into a glass of water
7.
8.
9.
5
10. Write C for Chemical Reaction or P for Physical Reaction.
A.
Burning Leaves
B.
Cutting Diamonds
C.
rushing a pencil
D.
Salivary Amylase breaking down food in the mouth
E.
Salt mixing in with water
Extension Questions
11. The following two figures represent changes in matter at the atomic scale. The blue and white
circles represent two different substances. Use the diagram to make predictions about the items
asked below.
A. Predict which Figure represents a physical change and which represents a chemical change.
Support your prediction with reason.
B. Predict which Figure represents a change in state (solid, liquid, or gas)? Support your response.
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