P/C Changes 1
Name ______________________________________________ Date _________ Period ______
Physical and Chemical Changes
Purpose
After reading the lab, create your own purpose below:
______________________________________________________________________________
______________________________________________________________________________
Pre-Lab Discussion (Do not copy in your lab book)
Chemistry is the study of matter and the changes it undergoes. These changes can be broken
into two classes – physical changes and chemical changes. In a physical change, one or more
physical properties of a substance are altered. Examples of such physical properties include size,
shape, color, and physical phase. No new substance or substances are formed as a result of a
physical change.
A chemical change results in the formation of one or more “new” substances. These new
substances differ in chemical properties and composition from the original substance. The
rusting of iron and the combustion of gasoline are two examples of chemical change.
Materials
Balance
Beakers
Bunsen Burner
Candle
Magnet
Matches
Microspatula
Mortar and Pestle
Paper
Pipet
Scoopulas
Straw
Striker
Test Tubes
Test Tube Holder
Test Tube Rack
Watch Glass
Weighing Boats
1.0 M Hydrochloric acid (HCl)
1.0 M Silver Nitrate (AgNO3)
Copper Sulfate Pentahydrate (CuSO4•5H2O)
Iron (Fe)
Limewater
Magnesium (Mg)
Nichrome Wire
Sodium Chloride (NaCl)
Sulfur (S)
Water Bottles
Procedure
Station 1 – Candle and Metals
1. Light the candle, and then allow it to burn while you take observations.
2. Take an initial observation of the nichrome wire. Hold the wire in the flame near the wick
until it glows red. Take the wire out of the flame and record observations as the wire
cools. Do not touch the wire for 2 minutes after heating.
3. Repeat step 2 with the iron wire. When finished, softly blow out the candle.
P/C Changes 2
Station 2 – Paper and Bubbles
4. Tear a piece of paper into small pieces. Place the paper onto a watch glass and record
observations.
5. Ignite the paper with a match and allow it to burn. Record observations.
6. Pipet 10 mL of limewater into a 50 mL beaker. Record an initial observation and using a
straw, exhale and blow bubbles into the liquid. Record observations after approximately
1.5 minutes of exhaling.
7. Repeat step 6 for 10 mL of H2O in the other beaker.
Station 3 – Salt
8. Use a microspatula to add a tiny scoop sodium chloride (NaCl) into about 5 mL of water
(~1 in. at the bottom of a test tube). Shake the tube vigorously and record observations.
9. Wearing a glove, add a dropperful of 0.1 M silver nitrate (AgNO3) to the NaCl mixture.
Record observations.
Station 4 – Magnesium
10. Obtain a piece of magnesium ribbon. Tear the ribbon into small pieces and record
observations.
11. Place the pieces of the magnesium in a test tube. Then two droppersful of 1.0 M
hydrochloric acid (HCl) to the test tube. Record observations. Touch the bottom of the
test tube with your fingertip and record a temperature observation.
Station 5 – Copper Sulfate Pentahydrate
12. Use a mortar and pestle to grind a crystal of copper sulfate pentahydrate (CuSO4•5H2O)
into a uniform powder. Record observations.
13. Place 1 microspatula of the powder into a test tube. Heat gently over a burner flame for
~1.5 minutes. Allow the sample to cool while you record observations.
14. When cool to the touch, add a few drops of water to the test tube using a wash bottle.
Record observations.
Station 6 – Sulfur and Iron Filings
15. Using a balance and weighing paper, measure out about 0.50 g of iron filings and 0.50 g
of sulfur.
16. Mix the samples thoroughly in a test tube. Run the magnet along the bottom and sides of
the test tube and record observations.
17. Heat the iron-sulfur mixture over a burner flame until the mixture “glows” and record
observations. Allow the sample to cool and examine it by probing it with a microspatula.
18. Run the magnet along the test tube again and record observations.
P/C Changes 3
Data
Table 1 – Observations
Change
a.
Burning of the Candle
b.
Nichrome Wire in Candle
c.
Iron Wire in Candle
d.
Ripping Paper
e.
Burning Paper
Observations
Station
1
2
f.
Limewater and Bubbles
g.
Water and Bubbles
h.
Mixing Salt with Water
3
i.
Saltwater + Silver Nitrate
j.
Ripping Magnesium Ribbon
4
k.
Magnesium + Hydrochloric Acid
l.
Grinding Copper Sulfate Pentahydrate
m.
Heating Copper Sulfate Pentahydrate
n.
Adding Water After Heating CuSO4
o.
Mixing Iron and Sulfur Before Heating
5
6
p.
Iron and Sulfur Mixture After Heating
P/C Changes 4
Questions (Answer on a separate sheet of paper, then attach to this sheet)
1. Name 3 possible indications that a chemical change has taken place. Use example(s) from
this lab to illustrate the changes.
2. Chemical change involves the formation of “new” substances. Briefly describe the “new”
substances (there were 8) formed as a result of each chemical change in this experiment.
3. The following changes do not always indicate a chemical change. Give examples in
which they may be the result of a physical change.
a. Change of color
b. Apparent loss of mass
c. Apparent disappearance of a substance
4. How can substances in a mixture be separated? How can substances in a compound be
separated? Use examples from this experiment in your explanation.
Conclusion
For each observation in your chart (a-p), indicate whether the changes were physical or
chemical. Include support for your conclusions.