STUDENT EDITION
A Glencoe Program
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CHEMISTRY CBL LABORATORY MANUAL
Contents
To the Student . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
Organization of Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
Sending Data to Graphical Analysis . . . . . . . . . . . . . . . . . . . . . . . . . v
CBL Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Safety in the Laboratory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
Safety Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Laboratory Activities
1
Quantitative and Qualitative Observations . . . . . . . . . . . . . . . . . 1
2
Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3
Melting and Freezing Points . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4
Boyle’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5
Gay-Lussac’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6
Determining Molar Mass Using Freezing Point Depression . . . 21
7
Calorimetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8
Hess’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
9
Determine the Molar Mass of an Unknown Acid . . . . . . . . . . . 33
10 Reaction Potentials of Metals . . . . . . . . . . . . . . . . . . . . . . . . . 37
Chemistry CBL Laboratory Manual
iii
To the Student
Chemistry is the science of matter, its properties, and changes. In your classroom
work in chemistry, you will learn a great deal about the information that has been
gathered by scientists about matter. But, chemistry is not just information. It is
also a process for finding out more about matter and its changes. Laboratory
activities are the primary means that chemists use to learn more about matter.
The activities in the Chemistry CBL Laboratory Manual require that you form
and test hypotheses, measure and record data and observations, analyze those
data, and draw conclusions based on those data and your knowledge of chemistry. These processes are the same as those used by professional chemists and all
other scientists.
CBL (computer-based laboratory) activities use graphing calculators to collect
and analyze real-world data using different probes or sensors. The CBL system is
an interface that collects data from the probes and sends the information to the
calculator. The calculator, in turn, runs stored data collection and processing
programs, which interpret and plot data obtained from the CBL system.
• Introduction Following the title and number of each activity, an introduction
provides a background discussion about the problem you will study in the activity.
• Problem The problem to be studied in this activity is clearly stated.
• Objectives The objectives are statements of what you should accomplish by doing
the investigation. Recheck this list when you have finished the activity.
• Materials The materials list shows the apparatus you need to have on hand for the
activity.
• Safety Precautions Safety symbols and statements warn you of potential hazards
in the laboratory. Before beginning any activity, refer to page vii to see what these
symbols mean.
• Pre-Lab The questions in this section check your knowledge of important
concepts needed to complete the activity successfully.
• Procedure The numbered steps of the procedure tell you how to carry out the
activity and sometimes offer hints to help you be successful in the laboratory.
Some activities have CAUTION statements in the procedure to alert you to
hazardous substances or techniques.
• Hypothesis This section provides an opportunity for you to write down a hypothesis for this activity.
• Data and Observations This section presents a suggested table or form for
collecting your laboratory data. Always record data and observations in an organized way as you do the activity.
• Analyze and Conclude The Analyze and Conclude section shows you how to
perform the calculations necessary for you to analyze your data and reach conclusions. It provides questions to aid you in interpreting data and observations in
order to reach an experimental result. You are also asked to form a scientific
conclusion based on what you actually observed, not what “should have
happened.” An opportunity to analyze possible errors in the activity is also given.
• Real-World Chemistry The questions in this section ask you to apply what you
have learned in the activity to other real-life situations. You may be asked to make
additional conclusions or research a question related to the activity.
iv
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Organization of Activities
CHEMISTRY CBL LABORATORY MANUAL
Sending Data to Graphical Analysis
If using the TI-83 graphing calculator:
1. On the TI calculator, press 2nd Link, then select 4:List… from the SEND menu.
2. Use the down arrow to locate the lists on the SELECT menu. Position the arrow in front
of a list you want to send to GRAPHICAL ANALYSIS and press ENTER to select that
particular list. More than one list may be selected in this manner. A filled box will appear
beside each list that will be sent. To deselect, press ENTER. The filled-in box will
disappear.
3. Press the right arrow on the calculator, then select 1:TRANSMIT. The lists will appear in
columns in the data table window of GRAPHICAL ANALYSIS. They will be labeled with
simple list names from the calculator. If you want to rename the lists or add units, doubleclick on the column heading and enter a new name or label in the dialog box.
If using another type of TI graphing calculator with a PC computer:
1. Connect the TI-graph link cable to a free serial port of the Windows computer and to the
port on the bottom edge of the TI calculator.
2. With GRAPHICAL ANALYSIS running, choose Import from the TI Calculator under the
FILE MENU. If the TI-graph link cable is not connected to the serial port designated in
the status box, click on SELECT PORT and choose the correct port for the TI-graph link
cable.
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
CBL Equipment
This diagram shows the basic equipment used in most of these CBL activities. Such
equipment includes the CBL unit, a graphing calculator, link cable, AC adapter for the
CBL unit, DIN adapter (needed for some probes), and a probe or sensor.
DIN adapter
TI-83 calculator
CBL
unit
Gas pressure
sensor
Syringe
AC adapter
Link cable
Chemistry CBL Laboratory Manual
v
CHEMISTRY CBL LABORATORY MANUAL
Safety in the Laboratory
The chemistry laboratory is a place to experiment and learn. You must assume responsibility
for your own personal safety and that of people working near you. Accidents are usually
caused by carelessness, but you can help prevent them by closely following the instructions
printed in this manual and those given to you by your teacher. The following are some safety
rules to help guide you in protecting yourself and others from injury in a laboratory.
2. Study your lab activity before you come to the
lab. If you are in doubt about any procedures, ask
your teacher for help.
3. Safety goggles and a laboratory apron must be
worn whenever you work in the lab. Gloves
should be worn whenever you use chemicals that
cause irritations or can be absorbed through the
skin.
4. Contact lenses should not be worn in the lab, even
if goggles are worn. Lenses can absorb vapors and
are difficult to remove in an emergency.
5. Long hair should be tied back to reduce the
possibility of it catching fire.
6. Avoid wearing dangling jewelry or loose, draping
clothing. The loose clothing may catch fire and
either the clothing or jewelry could catch on
chemical apparatus.
7. Wear shoes that cover the feet at all times. Bare
feet or sandals are not permitted in the lab.
8. Know the location of the fire extinguisher, safety
shower, eyewash, fire blanket, and first-aid kit.
Know how to use the safety equipment provided
for you.
9. Report any accident, injury, incorrect procedure, or
damaged equipment immediately to your teacher.
10. Handle chemicals carefully. Check the labels of
all bottles before removing the contents. Read
the labels three times: before you pick up the
container, when the container is in your hand,
and when you put the bottle back.
11. Do not return unused chemicals to reagent bottles.
12. Do not take reagent bottles to your work area
unless specifically instructed to do so. Use test
vi
tubes, paper, or beakers to obtain your chemicals.
Take only small amounts. It is easier to get more
than to dispose of excess.
13. Do not insert droppers into reagent bottles. Pour a
small amount of the chemical into a beaker.
14. Never taste any chemical substance. Never draw
any chemicals into a pipette with your mouth.
Eating, drinking, chewing gum, and smoking are
prohibited in the laboratory.
15. If chemicals come into contact with your eyes or
skin, flush the area immediately with large quantities of water. Immediately inform your teacher of
the nature of the spill.
16. Keep combustible materials away from open
flames. (Alcohol and acetone are combustible.)
17. Handle toxic and combustible gases only under the
direction of your teacher. Use the fume hood when
such materials are present.
18. When heating a substance in a test tube, be careful
not to point the mouth of the tube at another
person or yourself. Never look down the mouth
of a test tube.
19. Use caution and the proper equipment when
handling hot apparatus or glassware. Hot glass
looks the same as cool glass.
20. Dispose of broken glass, unused chemicals, and
products of reactions only as directed by your
teacher.
21. Know the correct procedure for preparing acid
solutions. Always add the acid slowly to the water.
22. Keep the balance area clean. Never weigh
chemicals directly on the pan of the balance.
23. Do not heat graduated cylinders, burettes, or
pipettes with a laboratory burner.
24. After completing an activity, clean and put away
your equipment. Clean your work area. Make sure
the gas and water are turned off. Wash your hands
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
1. The chemistry laboratory is a place for serious
work. Do not perform activities without your
teacher’s permission. Never work alone in the laboratory. Work only when your teacher is present.
CHEMISTRY CBL LABORATORY MANUAL
Chemistry uses safety symbols to alert you to possible laboratory dangers. These symbols are provided in
the textbook and are explained below. Be sure you understand each symbol before you begin an activity that
displays a symbol.
SAFETY SYMBOLS
EXAMPLES
PRECAUTION
REMEDY
Special disposal procedures need to be
followed.
certain chemicals,
living organisms
Do not dispose of
these materials in the
sink or trash can.
Dispose of wastes as
directed by your
teacher.
Organisms or other
biological materials
that might be harmful
to humans
bacteria, fungi, blood,
unpreserved tissues,
plant materials
Avoid skin contact
with these materials.
Wear mask or gloves.
Notify your teacher if
you suspect contact
with material. Wash
hands thoroughly.
Objects that can burn boiling liquids, hot
skin by being too cold plates, dry ice, liquid
or too hot
nitrogen
Use proper protection
when handling.
Go to your teacher for
first aid.
SHARP
OBJECT
Use of tools or glassware that can easily
puncture or slice skin
razor blades, pins,
scalpels, pointed
tools, dissecting
probes, broken glass
Practice commonsense behavior and
follow guidelines for
use of the tool.
Go to your teacher for
first aid.
FUME
Possible danger to
respiratory tract from
fumes
ammonia, acetone,
nail polish remover,
heated sulfur, moth
balls
Make sure there is
Leave foul area and
good ventilation.
notify your teacher
Never smell fumes
immediately.
directly. Wear a mask.
ELECTRICAL
Possible danger from
electrical shock or
burn
improper grounding,
liquid spills, short
circuits, exposed
wires
Double-check setup
with teacher. Check
condition of wires and
apparatus.
Do not attempt to fix
electrical problems.
Notify your teacher
immediately.
Substances that can
irritate the skin or
mucous membranes
of the respiratory tract
pollen, moth balls,
steel wool, fiberglass,
potassium permanganate
Wear dust mask and
gloves. Practice extra
care when handling
these materials.
Go to your teacher for
first aid.
Chemicals that can
react with and destroy
tissue and other materials
bleaches such as
hydrogen peroxide;
acids such as sulfuric
acid, hydrochloric
acid; bases such as
ammonia, sodium
hydroxide
Wear goggles, gloves, Immediately flush the
and an apron.
affected area with
water and notify your
teacher.
Substance may be
poisonous if touched,
inhaled, or swallowed
mercury, many metal
compounds, iodine,
poinsettia plant parts
Follow your teacher’s
instructions.
Always wash hands
thoroughly after use.
Go to your teacher for
first aid.
Tie back hair. Avoid
wearing loose clothing.
Avoid open flames
when using flammable
chemicals. Be aware of
locations of fire safety
equipment.
Notify your teacher
immediately. Use fire
safety equipment if
applicable.
DISPOSAL
BIOLOGICAL
EXTREME
TEMPERATURE
IRRITANT
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
HAZARD
CHEMICAL
TOXIC
OPEN
FLAME
Open flame may ignite alcohol, kerosene,
flammable chemicals, potassium permanloose clothing, or hair ganate, hair, clothing
Eye Safety
Proper eye protection should be worn
at all times by anyone performing or
observing science
activities.
Chemistry CBL Laboratory Manual
Clothing
Protection
This symbol appears
when substances
could stain or burn
clothing.
Radioactivity
This symbol appears
when radioactive
materials are used.
Handwashing
After the lab, wash
hands with soap and
water before removing
goggles.
vii
Name
LAB
Date
1
Class
CHEMISTRY CBL LABORATORY MANUAL
Quantitative and
Qualitative Observations
R
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
eactions are taking place around you all the time. It is important
to be aware of your surroundings and understand how humans
interact with these surroundings. Your five senses allow you to
observe the world in which you live. In the lab, you only use four
senses to make observations. Nothing is ever tasted in the lab.
Sometimes tools can extend your senses. When you describe the
color, odor, or texture of an object, you are making a qualitative
observation. Quantitative observations involve measured quantities,
such as 15 g or 2.5 L. It is important not to confuse observations and
interpretations in the lab. Observations are made using your senses;
interpretations are proposed explanations that are based on
observations. In this lab, you will be making both qualitative and
quantitative observations.
Problem
Objectives
Materials
How many observations
can you make about a
reaction? Are your
observations qualitative
or quantitative?
• Measure the change in
temperature related to a
chemical reaction.
• Compare quantitative
observations and qualitative observations.
• Discuss the difference
between observations
and interpretations.
• Predict one product
produced during the
reaction.
CBL unit
TI graphing
calculator
link cable
temperature probe
copper(II) chloride
2 2-in square of
aluminum foil
150-mL beaker
100-mL graduated
cylinder
microspatula
glass stirring rod
paper towel
magnifying glass
weighing paper
Safety Precautions
•
•
•
•
Always wear safety goggles and a lab apron.
Do not touch chemicals with bare skin.
Do not inhale vapors that are released.
Dispose of materials as your teacher instructs.
Pre-Lab
1. What is the difference between observations and
interpretations?
2. Give three examples of qualitative observations
and three examples of quantitative observations.
Chemistry CBL Laboratory Manual
3. What are some tools that scientists use to enhance
their observational techniques?
1
Name
Date
1
CHEMISTRY CBL LABORATORY MANUAL
4. Using the 100-mL graduated cylinder, obtain
Procedure
Part A: Preparing the CBL System
1. Connect the CBL unit to the temperature probe,
5.
as shown in Figure A. Make sure the temperature probe is in channel 1. Then, using a link
cable, connect the CBL unit to the graphing
calculator.
6.
Figure A
TI graphing
calculator
CBL
unit
Temperature
probe
7.
8.
9.
AC adapter
Link cable
10.
2. Turn on the CBL unit and the graphing calcula-
tor. Press the PRGM button on the calculator
and choose ChemBio from the list of programs.
Press ENTER on the calculator twice.
3. Choose SET UP PROBES from the MAIN
MENU. Enter 1 as the number of probes.
On the SELECT PROBES menu, choose
TEMPERATURE. Enter 1 as the channel
number.
4. From the MAIN MENU, select COLLECT
DATA. On the DATA COLLECTION menu,
select TRIGGER/PROMPT.
Part B: Collecting Data
1. Obtain a 2 2-in square of aluminum.
2. Place a small scoop of copper(II) chloride onto
a piece of weighing paper.
3. Make as many observations of the aluminum
and the copper(II) chloride as possible. Record
your observations in Data Table 1.
2
11.
12.
50 mL of distilled water. Pour the water into the
150-mL beaker.
Place the temperature probe in the water.
Record an initial temperature of the water by
pressing TRIGGER on the CBL unit. Follow
directions on the calculator to continue
collecting data.
With the temperature probe in the water, transfer the copper(II) chloride into the water
without touching the probe. Try not to agitate
the mixture. Note any temperature change.
Before stirring the mixture, record as many
observations as possible in Data Table 1.
Using the glass stirring rod, stir the mixture.
After stirring, make and record as many observations as possible.
Roll the aluminum foil loosely into a ball. Do
not tightly pack the aluminum. Place the foil
ball in the copper(II) chloride mixture. Let the
reaction proceed for about 15 min. Make and
record as many observations as possible of the
reaction mixture.
Record the maximum temperature change that
takes place during the reaction.
When the reaction appears to be complete,
remove the probe from the water. Pour off as
much of the liquid as possible.
Label a paper towel with your name and class
period. Pour the remaining contents onto the
paper towel. Set aside the paper towel for
observation on the second day of lab.
Cleanup and Disposal
1. Disconnect the temperature probe from the
CBL unit.
2. After emptying the beaker, clean and rinse the
beaker. Rinse the probe with distilled water and
carefully wipe it dry.
3. Return all equipment to its proper place.
4. Clean up the lab area and wash your hands with
soap or detergent before leaving the lab.
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
LAB
Class
Name
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LAB
1
Class
CHEMISTRY CBL LABORATORY MANUAL
Data and Observations
Data Table 1
Steps
Observations
3. Dry copper(II) chloride
Aluminum
5. Initial temperature of water (°C)
7. Copper(II) chloride and water mixture
before stirring
8. Copper(II) chloride and water mixture
after stirring
9. Copper(II) chloride and water mixture
with aluminum
10. Final temperature of mixture (°C)
Analyze and Conclude
1. Observing and Inferring Describe the events that took place that provide evidence for
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
a chemical reaction.
2. Observing and Inferring Name one product that is formed in this reaction.
3. Observing and Inferring What observations did you make during this lab? What
interpretations can you make from your observations?
4. Thinking Critically Which of the observations you made were quantitative?
Chemistry CBL Laboratory Manual
3
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Class
CHEMISTRY CBL LABORATORY MANUAL
5. Error Analysis What could be done to improve the accuracy of your measurements in
this activity?
Real-World Chemistry
1. Why is it important for scientists to have
3. How do observation and interpretation skills
help when working with the scientific method?
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
as much data as possible before making
interpretations?
2. Why is important for high school students to
develop their observation skills?
4
Chemistry CBL Laboratory Manual
Name
LAB
Date
2
Class
CHEMISTRY CBL LABORATORY MANUAL
Conductivity
T
he solubility of a substance describes the ability of one substance
to dissolve in another substance. Water is used as a solvent to
determine the solubility of various solids. Some substances dissolve in
water; some substances do not.
When dissolved in water, the ions in an ionic compound separate,
or dissociate. As the ions dissociate, electrons are free to move about
in the solution. As these electrons move, it is possible for them to
carry an electric current.
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
In this activity, the conductivity of substances is used to determine
to what extent substances dissociate in water. This lab compares an
ionic solid to a nonionic substance and relates the effect of
concentration on conductivity.
Problem
Objectives
Materials
How can an electric current
be used to determine the
extent to which solid substances dissolve in water?
• Predict what substances
will dissociate in water
based on their chemical
makeup.
• Write balanced equations
for the dissociation of
substances in water.
• Compare the conductivity
of various solutions.
• Classify substances as
nonionic or ionic.
• Determine what effect
concentration has on
conductivity.
CBL unit
TI graphing
calculator
computer
link cable
conductivity probe
adapter cable
dropper bottles (3)
with:
(a) 1M NaCl
(b) 1M MgCl2
(c) 1M AlCl3
50-mL beakers (2)
with:
(a) NaCl
(b) sugar
(C12H22O11)
400-mL beaker
150-mL beakers (3)
100-mL graduated
cylinder
glass stirring rod
ring stand with
test-tube clamp
wash bottle of
distilled water
microspatula
electronic balance
weighing dishes (2)
plastic beral
pipettes (3)
Safety Precautions
• Always wear safety goggles and a lab apron.
• Use caution when working with electricity.
• The conductivity probe is fragile. Use caution when setting this up in
the ring stand.
• Never taste any chemical substances.
Chemistry CBL Laboratory Manual
5
Name
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2
CHEMISTRY CBL LABORATORY MANUAL
4. Turn on the CBL unit and the graphing calculator.
Pre-Lab
1. Read over the entire laboratory activity. Write
balanced chemical equations for the dissociation
of NaCl, MgCl2 and AlCl3 in water. Form a
hypothesis as to which of these compounds
would conduct the most electricity and the least
electricity. Record your hypothesis on the next
page.
2. Which of the following substances would be considered ionic? Which would be nonionic? Explain
your reason for each answer.
a. potassium chloride (KCl)
b. methanol (CH3OH)
c. glucose (C6H12O6)
d. hydrochloric acid (HCl)
e. zinc oxide (ZnO)
3. Sketch a diagram of NaCl dissolving in water.
Choose ChemBio from the list of programs. Press
ENTER on the calculator twice.
5. Choose SET UP PROBES from the MAIN
MENU. Enter 1 as the number of probes. On the
SELECT PROBES menu, choose CONDUCTIVITY. Enter 1 as the channel number. Then select
USE STORED from the CALIBRATION menu
and select H 0-2000 MICS from the CONDUCTIVITY menu. Make sure the switch on the box
is set to the same value.
6. From the MAIN MENU, select COLLECT
DATA. On the DATA COLLECTION menu,
select TRIGGER PROMPT. Allow the unit to
warm up and then press ENTER.
Part B: Comparing Ionic Compounds
1. Label three beral pipettes—NaCl, MgCl2, and
Procedure
Part A: Preparing the CBL System
If your teacher has the CBL system set up, you may
skip to Part B.
1. Set up a ring stand, clamp, and CBL probe as
illustrated in Figure A.
2. Plug the conductivity probe into the adapter cable
in channel 1 of the CBL unit.
3. Connect the CBL unit to the graphing calculator
with a link cable.
Figure A
2.
3.
4.
Ring stand
Conductivity
probe
Test-tube
clamp
5.
Graphing
calculator
CBL unit
Beaker
6.
7.
Link
cable
6
AlCl3. Fill one of the pipettes with the 1.0M solution of NaCl. Fill the other two pipettes with
1.0M MgCl2 and AlCl3, respectively.
Using the 100-mL graduated cylinder, measure
70 mL of distilled water into the 150-mL beaker.
Raise the beaker until the conductivity probe is in
the water. After the conductivity meter stabilizes,
press TRIGGER on the CBL unit.
Measure and record the conductivity of the distilled water in Data Table 1.
Lower the beaker and place 1 drop of NaCl solution into the distilled water. Stir with the glass
stirring rod and then raise the beaker until the
conductivity probe is in the solution. After the
conductivity meter stabilizes, press TRIGGER on
the CBL unit. Measure and record the conductivity of this solution in Data Table 1.
Adding 1 more drop of the NaCl solution, repeat
step 4. Continue adding 1 drop and recording its
conductivity until a total of 8 drops of NaCl solution has been added.
If a TI-83 graphing calculator is being used, or
another type of graphing calculator and a computer is available, refer to Appendix A for
instructions on how to convert this data into
graphical analysis.
After transferring the data to the graphing program, rinse out the beaker with distilled water
and repeat steps 4–6 two more times using MgCl2
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
LAB
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Class
CHEMISTRY CBL LABORATORY MANUAL
and AlCl3, respectively. Be sure to transfer the
data to the graphing program and rinse out the
beaker after each substance. Rinse the conductivity probe with distilled water in between each
substance. (Do this by spraying the probe over
the 400-mL beaker or sink.)
Part C: Comparing Ionic and Molecular
Substances
4. Use the conductivity probe to monitor the con-
ductivity of the sodium chloride solution. Record
the conductivity in Data Table 2.
5. Rinse the probe with distilled water.
6. Use the conductivity probe to monitor the conductivity of the sucrose solution. Record the
conductivity in Data Table 2.
Cleanup and Disposal
1. In two separate weighing dishes, measure 10 g
of sodium chloride (NaCl) and 10 g of sucrose
(C12H22O11).
2. Using the 100-mL graduated cylinder, place
50 mL of distilled water in each of two 150-mL
beakers. Label one of the beakers sodium chloride (NaCl) and the other beaker sucrose
(C12H22O11).
3. Pour the solid sodium chloride and sucrose into
the appropriate beakers and stir with a glass
stirring rod.
1. Disconnect the conductivity probe from the CBL
unit.
2. Rinse the probes with distilled water.
3. Rinse out the beakers with distilled water.
4. Clean up your lab area and wash your hands.
Replace the lab equipment to the appropriate area.
Hypothesis
Data and Observations
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Data Table 1 (to be used if graphing program not available)
Drops
NaCl conductivity
(microsiemens)
MgCl2 conductivity
(microsiemens)
AlCl3 conductivity
(microsiemens)
0
1
2
3
4
5
6
7
8
Data Table 2
Substance
Conductivity
Sodium chloride (NaCl)
Sucrose (C12H22O11)
Chemistry CBL Laboratory Manual
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Analyze and Conclude
1. Observing and Inferring Which solution was the best conductor of electricity? Explain.
2. Making and Using Graphs Make a graph of conductivity versus concentration. Plot
conductivity on the y-axis and concentration (number of drops) on the x-axis. If you used a
graphing program, you may use those graphs. Draw a line of best fit for each of these sets
of data.
AlCl3, what is the ratio of number of electrons transferred in each reaction? How does this
explain the graphs drawn in question 2?
4. Drawing a Conclusion How does the conductivity of sodium chloride compare with
sucrose? Why is this the case?
Real-World Chemistry
What types of substances make good conductors of electricity? What element is used to
bring electricity to the places where we live? Why is this an effective substance?
8
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
3. Observing and Inferring For each of the dissociation reactions of NaCl, MgCl2 and
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CHEMISTRY CBL LABORATORY MANUAL
Melting and Freezing Points
W
hen you add heat to a substance, the average kinetic energy of
the particles in the substance increases. If enough energy is
added, the particles overcome the attractive forces holding the particles
together and the substance changes state—from a solid to a liquid, or
even to a gas. As this happens, the movement of the particles becomes
more random. By contrast, as substances lose heat, the interactions
between particles increases and the particles become more ordered.
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
The temperature of a substance stays the same during any change of
state, or phase change. The energy absorbed by the system is used to
overcome intermolecular attractions, not to increase the kinetic energy
(temperature) of the substance. In this lab, you will determine the
melting/freezing point for water and a food preservative, BHT
(butylated hydroxytoluene, C15H24O).
Problem
Objectives
Materials
What are the melting/
freezing points of water
and BHT (C15H24O)?
• Describe the process of
melting and freezing.
• Determine the melting
and freezing points of
two substances.
• Predict which substance
will have a higher or
lower melting/freezing
point.
CBL unit
TI graphing
calculator
link cable
temperature probe
AC adapter
BHT
salt (NaCl)
ice
water
400-mL beaker
25-mL graduated
cylinder
20 150-mm test
tube
hot plate
ring stand
clamp
glass stirring rod
Safety Precautions
•
•
•
•
•
Always wear safety goggles and a lab apron.
Use caution when working with the hot plate.
Never taste any of the chemicals used in the lab.
Do not touch the salt–ice solution. It will be extremely cold.
Dispose of materials as your teacher instructs.
Pre-Lab
1. Read the entire laboratory activity. Sketch a
representation of the solid, liquid, and gaseous
states of matter.
2. What terms are used to describe the following
phase changes: solid to liquid; liquid to gas; solid
to gas; gas to liquid; liquid to solid?
Chemistry CBL Laboratory Manual
3. Research the heating curve for water. Describe
each portion of the curve and explain why it has
that particular shape.
9
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CHEMISTRY CBL LABORATORY MANUAL
Procedure
6. Now lower the test tube of water into the
Part A: Preparing the CBL System
1. Connect the CBL unit to the temperature probe,
as shown in Figure A. Make sure the temperature probe is in channel 1. Then, using a link
cable, connect the CBL unit to the graphing calculator.
2. Turn on the CBL unit and the graphing calculator. Press the PRGM button on the calculator
and choose ChemBio from the list of programs.
Press ENTER on the calculator twice.
3. Choose SET UP PROBES from the MAIN
MENU. Enter 1 as the number of probes.
On the SELECT PROBES menu, choose
TEMPERATURE. Enter 1 as the channel
number. Select USE STORED from the
CALIBRATION MENU.
Part B: Collecting Freezing Point Data
1. Fill a 400-mL beaker half full with ice, and then
2.
3.
4.
5.
add 100 mL of water.
Put 5–7 mL of water into a test tube and set up
the apparatus as shown in Figure A. Do not
lower the test tube of water into the ice water
until you have set up the calculator for data
collection. (See step 3.)
From the MAIN MENU, select COLLECT
DATA. On the DATA COLLECTION menu,
select TIME GRAPH. Enter 15 as the time
(in s) between samples and then enter 80 as the
number of samples. The CBL unit will collect
data for 20 min.
Press ENTER; then select USE TIME SETUP
to continue. Note: If you want to change the
sample time or sample number you entered,
select MODIFY SETUP.
Enter 15 as the minimum temperature (Ymin)
and 100 as the maximum temperature (Ymax).
Enter 1 as the temperature increment (Yscl).
7.
8.
9.
10.
11.
beaker of ice water and press ENTER on the
calculator to begin data collecting.
After lowering the test tube, add 5 spoonfuls of
salt to the beaker and stir with a stirring rod.
Continue to stir the ice water.
During data collection, slowly stir the water in
the test tube containing the temperature probe.
If all the ice in the beaker melts, add additional
pieces of ice to the beaker.
Once crystals begin to form in the water, stop
stirring and let the probe freeze in the water.
After 20 minutes, the CBL will stop collecting
data. If you think the lab is complete before
20 minutes, you may stop the run by pressing
the <ON> button of the calculator to stop the
program.
See page v for sending data for graphical
analysis.
On the displayed graph, analyze the flat part of
the curve to determine the freezing temperature
of water. Save your data.
Ring stand
with clamp
Temperature
probe
Graphing
calculator
Test tube
with water
or BHT
CBL unit
Beaker with
ice water
Link
cable
Figure A
10
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
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CHEMISTRY CBL LABORATORY MANUAL
Part C: Collecting Melting Point Data
1. Set up the CBL for taking data as in steps 3–5
of Part B.
2. Take the test tube of frozen water out of the ice
bath and place it in the hot-water bath. Heat the
test tube slowly. Allow the CBL to take data
until the water has completely melted. Follow
directions on page X to save your data.
Part D: Collecting BHT Data
Cleanup and Disposal
1. Dispose of the salt–ice solution following your
teacher’s directions.
2. Place the BHT test tube in the hot-water bath
your teacher has prepared.
3. Clean up the lab area and wash your hands with
soap or a detergent.
Data and Observations
Data Table 1
Obtain a BHT test tube that your teacher has prepared for you. Repeat parts B and C using the BHT.
Substance
Freezing
point (°C)
Melting
point (°C)
Water
BHT
Analyze and Conclude
1. Observing and Inferring What is the freezing point of water? Of BHT? What evidence
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
do you have?
2. Collecting and Interpreting Data What is the relationship between melting point and
freezing point? Explain your answer.
3. Recognizing Cause and Effect Use the concept of molecular motion to describe why
the temperature does not change during a phase change.
Chemistry CBL Laboratory Manual
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4. Drawing a Conclusion Look at the structures of water and of BHT. Suggest an
explanation for the differences in their melting/freezing points.
5. Thinking Critically What role did the salt play in this investigation?
Real-World Chemistry
1. How could a scientist know if he or she had
2. Why does ice float in a glass of water?
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
pure water or pure BHT based on the tests you
just completed?
12
Chemistry CBL Laboratory Manual
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CHEMISTRY CBL LABORATORY MANUAL
Boyle’s Law
S
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
uppose you have a basketball containing a given volume of air. If
you were to sit on the ball, its volume would decrease. What
happens to the particles of air inside the ball? They would be forced
to occupy a smaller volume. Because the particles are more crowded,
collisions among particles and between the particles and the inside
surface of the ball increase. This increase in the number of collisions
causes an increase in pressure inside the ball. The relationship
between the volume of a gas and the pressure it exerts is known as
Boyle’s law, and it can be studied in a laboratory setting.
Problem
Objectives
Materials
What is the relationship
between the volume and
pressure in a closed system?
• Collect data that relate
pressure to volume.
• Analyze laboratory data
and develop a mathematical expression to show
the relationship between
pressure and volume.
• Calculate pressure of an
unknown gas.
CBL unit
TI graphing
calculator
link cable
AC adapter for CBL
unit
CBL-DIN adapter
gas pressure sensor
syringe
Safety Precautions
• Always wear safety goggles and a lab apron.
• Use caution when pushing on syringe.
• Use caution when making electrical connections.
Pre-Lab
1. Sketch three syringes at equal temperature and
containing an equal number of gas particles.
Show the plungers at three different volumes—
5 mL, 15 mL, and 20 mL. Use dots to represent
the gas particles. How do the contents of the three
syringes appear to be different? How does the
pressure differ in the three syringes?
Chemistry CBL Laboratory Manual
2. What is the definition of pressure, volume, and
temperature?
3. Read over the entire laboratory activity. Form
a hypothesis as to how volume and pressure
are related in a closed system. Record your
hypothesis on page 14.
4. What variables are changed in this lab? What is
held constant?
13
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CHEMISTRY CBL LABORATORY MANUAL
Figure A
DIN adapter
TI calculator
CBL
unit
Gas pressure
sensor
Syringe
AC adapter
for CBL unit
Link cable
2. Press the plunger of the syringe down to the 5
Part A: Preparing the CBL System
1. Connect the syringe to the gas pressure sensor.
Then connect the CBL unit to both the gas pressure sensor and the graphing calculator as shown
in Figure A. Make sure the gas pressure sensor
probe is in channel 1.
2. Turn on the CBL unit and the graphing calculator.
Press the PRGM button on the calculator and
choose ChemBio from the list of programs. Press
ENTER on the calculator twice.
3. Choose SET UP PROBES from the MAIN
MENU. Enter 1 as the number of probes. On the
SELECT PROBES menu, choose PRESSURE.
Enter 1 as the channel number. Then select USE
STORED from the CALIBRATION menu and
select ATM for your units. You will be returned to
the MAIN MENU.
4. From the MAIN MENU, select COLLECT
DATA. On the DATA COLLECTION menu,
select TRIGGER PROMPT. Follow the directions
on the calculator to collect data.
3.
4.
5.
6.
mL mark. When the pressure gauge stops changing, press TRIGGER on the CBL unit. Enter 5 as
the mL on the graphic calculator.
From the DATA COLLECTION menu, select
MORE DATA.
Repeat steps 1 through 3, pressing the plunger
of the syringe down to the 7.5 mL, 10.0, mL,
12.5 mL, 15.0 mL, 17.5 mL, and 20.0 mL marks.
After the last set of data, select STOP AND
GRAPH.
Select GRAPH on your calculator to see a line
graph. Press STAT and then choose EDIT. The
data are now displayed. Volume will be in
Column 1 and pressure will be in Column 2.
Record these data in Data Table 1.
Cleanup and Disposal
Disconnect the sensor from the CBL unit. Following
your teacher’s directions, return all equipment to its
proper place.
Hypothesis
Part B: Collecting Data
1. Open the blue valve between the atmosphere and
the syringe. Set the inside ring of the syringe to
the 20 mL mark and close the blue valve to the
atmosphere.
14
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Procedure
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Data and Observations
Data Table 1
Volume (mL)
Pressure (ATM)
Constant (pv or p/v)
5.0
7.5
10.0
Analyze and Conclude
1. Collecting and Interpreting Data As the volume changes from 10 to 20 mL, what
happens to the pressure?
2. Observing and Inferring Is the relationship between volume and pressure an inverse or
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
a direct relationship?
3. Thinking Critically Why is the graph you see a curved line, not a straight line? What
mathematical function would you have to graph to achieve a straight line?
4. Predicting Predict what the pressure of the gas in the syringe would be if the volume
was increased to 40 mL.
Chemistry CBL Laboratory Manual
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5. Recognizing Cause and Effect Why was it necessary to keep temperature and number
of gas particles constant during this activity?
6. Error Analysis What could be done to improve the accuracy of this investigation?
Real-World Chemistry
1. Why would it be important for a scuba diver to
2. What are some common household products
that utilize Boyle’s law?
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
be familiar with Boyle’s law?
16
Chemistry CBL Laboratory Manual
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CHEMISTRY CBL LABORATORY MANUAL
Gay-Lussac’s Law
H
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
ave you ever tried to bounce a cold basketball or walked outside
in the cold with a helium balloon? Why is it never advisable to
heat a sealed container? As you might predict, these items act in an
odd manner under different temperature conditions. Why does this
happen? In this lab, you will investigate the relationship between
temperature and pressure, as proposed by Joseph Gay-Lussac.
Problem
Objectives
Materials
What is the relationship
between the temperature
and pressure of a sealed
container of gas at a
constant volume?
• Develop a mathematical
expression to show the
relationship between
temperature and volume.
• Determine a temperaturevolume constant.
• Make calculations on
unknown gases based
on a determined
temperature-volume
constant.
CBL unit
TI graphing calculator
Vernier CBL pressure sensor (attached to
rubber stopper assembly)
Vernier temperature probe
1000-mL beakers (3)
150-mL Erlenmeyer flask
ice
thermal mitt
hot plate
Safety Precautions
• Always wear safety goggles and a lab apron.
• Use caution when working around a hot plate and hot glassware.
• Use caution when making electrical connections.
Pre-Lab
Procedure
1. What are temperature and pressure?
Part A: Preparing the CBL System
2. Describe these three containers in relationship to
1. Connect the CBL unit to the pressure sensor and
each other in terms of particle speed and collisions with the walls of the container. All have
same amounts of the same gas in them.
a. 1-L container at 25°C
b. 1-L container at 150°C
c. 1-L container at 300°C
3. Read over the entire lab activity. What variables
will be held constant in this lab?
temperature probe, as shown in Figure A. Make
sure the pressure sensor is in channel 1 and the
temperature probe is in channel 2. Use the link
cable to connect the CBL to the graphing
calculator.
2. Turn on the CBL unit and the graphing calculator.
Press the PRGM button on the calculator and
choose ChemBio from the list of programs. Press
ENTER on the calculator twice.
Chemistry CBL Laboratory Manual
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CHEMISTRY CBL LABORATORY MANUAL
3. Choose SET UP PROBES from the
Channel 2
Pressure
sensor
CBL unit
4.
5.
18
1000-mL
beaker
Link
cable
1. Prepare three water baths:
a. To prepare a boiling-water bath, pour about
3.
Erlenmeyer
flask
Graphing
calculator
Part B: Collecting Data
2.
Channel 1
800 mL of water into a 1000-mL beaker and
place it on a hot plate on high.
b. To prepare an ice-bath, pour about 700 mL of
cold tap water into a second 1000-mL beaker
and add ice.
c. Pour about 800 mL of room-temperature water
into a third 1000-mL beaker.
Insert the rubber stopper assembly, connected to
the pressure sensor, into the 150-mL Erlenmeyer
flask, with the valve open to the atmosphere.
Twist the stopper into the flask to insure a tight
fit. Close the valve to the atmosphere. If the stopper pops out at any time during the experiment,
you must start over. Begin with the hot water to
prevent this.
Carefully place the stoppered Erlenmeyer flask
into the hot-water bath with the temperature
probe in the beaker of water next to but not in the
flask, as illustrated in Figure A.
Now press ENTER on the calculator to begin
monitoring pressure and temperature.
After the temperature and a pressure have stabilized, press the TRIGGER button on the CBL
unit. This will store the temperature and pressure
in the list on the calculator. Follow the calculator
directions to take more data.
Figure A
6. After the temperature and pressure of the hot
water are recorded, carefully remove the flask
and place it in the room-temperature beaker with
the temperature probe beside the flask in the
water. Continue to monitor the CBL until it stabilizes and then press the TRIGGER button on the
CBL unit.
7. Repeat steps 3–6 for the beaker with the ice
water. Ask your teacher whether you should take
more data points. After three data points, press
END to stop collecting data.
8. Select GRAPH on your calculator. Press STAT
and then choose EDIT. The data are now displayed. Record these data in Data Table 1.
Cleanup and Disposal
1. Turn off your hot plate and unplug it.
2. Turn off the calculator and the CBL unit, and
then unplug them.
3. Return the CBL unit and the probes to the
appropriate location.
4. Clean up and organize your lab area.
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
MAIN MENU. Enter 2 as the number
of probes. On the SELECT PROBE
menu, choose PRESSURE. Enter 1 as
the channel number. Then select USE
STORED from the CALIBRATION
MENU and select ATM for your
units.
4. On the SELECT PROBE menu, next
choose TEMPERATURE. Enter 2 as
the channel number. Then select USE
STORED from the CALIBRATION
MENU and select COLLECT DATA
from the MAIN MENU. On the
DATA COLLECTION MENU, select
TRIGGER prompt. Follow the directions on the calculator to collect data.
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Data and Observations
Data Table 1
Trial
Pressure (atm)
Temperature (°C)
Temperature (K)
Constant (P T or P/T)
1
2
3
Analyze and Conclude
1. Measuring and Using Numbers Convert the Celsius temperatures to kelvin. Record
these temperatures in Data Table 1.
2. Observing and Inferring Is the relationship between temperature and pressure a direct
or an inverse relationship? Explain your answer.
3. Measuring and Using Numbers Determine a constant for this relationship. Is it P T
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
or P/T?
4. Predicting What would the pressure of the gas in the container be if the temperature
was 33°C?
5. Observing and Inferring Why was it necessary to keep the volume constant during this
experiment?
Real-World Chemistry
1. Why is it necessary for a hot-air balloonist,
who is traveling around the world, to be familiar with Gay-Lussac’s law?
Chemistry CBL Laboratory Manual
2. During which season should motorists keep
more air in their tires—winter or summer?
19
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CHEMISTRY CBL LABORATORY MANUAL
Determining Molar Mass
Using Freezing Point Depression
T
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
he freezing point depression of a solution is a colligative
property of the solution. A temperature versus time graph can
be used to determine the freezing point of a particular substance. A
plateau occurs on the graph at the freezing point because no change
in average kinetic energy of the system takes place as the phase
change occurs. This allows the freezing point of a pure substance to
be compared with that of a solution. From this comparison, it is
possible to determine the molecular mass of an unknown substance.
In this lab, an organic solute will be used to determine a freezing
point depression constant for the food additive BHT (butylated
hydroxytolune). Using this information, you will determine the
molecular mass of an unknown substance.
Problem
Objectives
Materials
What is the molecular mass
of an unknown substance?
• Describe the process of
melting and freezing.
• Collect data to determine
the Kf for BHT.
• Compare melting point
graphs to determine the
molecular mass of the
unknown substance.
• Analyze the results and
complete an error
analysis.
CBL unit
TI graphing
calculator
link cable
temperature probe
adapter cable
BHT (butylated
hydroxytoluene
C15H24O)
PDB (paradichlorobenzene)
unknown substance
400-mL beaker
1-mL graduated
cylinder
test tubes (2–3)
hot plate
ring stand
universal clamp
laboratory balance
copper wire stirrer
scoop
Safety Precautions
• Always wear safety goggles and a lab apron.
• Use caution when working with the hot plate.
• Some of these chemicals are flammable and may have toxic vapors;
you may want to work in a fume hood.
• Dispose of materials as your teacher instructs.
Pre-Lab
1. Sketch the cooling curve for water and identify
its key features.
2. What is molality?
Chemistry CBL Laboratory Manual
3. If 2.8 grams of NaCl is added to 50.0 grams of
water, at what temperature would you expect the
solution to freeze? (Density of water 1.0 g/cm3)
21
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4. What is the molar mass of BHT? What is the
6. Press ENTER and then select USE TIME SETUP
molar mass of PDB?
5. Read over the entire laboratory activity. Describe
the process you will use to melt the pure solids.
Part A: Preparing the CBL System
to continue. Note: If you wish to change the sampling time or number of samples, select MODIFY
SETUP.
7. Enter 15 as the minimum temperature (Ymin),
100 as the maximum temperature (Ymax), and 1 as
the temperature increment (Yscl).
1. Using the adapter cable, connect the CBL unit to
Part B: Collecting Data
Procedure
the temperature probe, as shown in Figure A.
Make sure the temperature probe is in channel 1.
Then, using a link cable, connect the CBL unit to
the graphing calculator
1. Add approximately 300 mL of water to the
2.
Adapter cable
CBL
unit
Temperature
probe
TI graphing
calculator
3.
Test tube
4.
5.
Figure A
Link cable
6.
2. Turn on the CBL unit and the graphing calculator.
Press the PRGM button on the calculator and
choose ChemBio from the list of programs. Press
ENTER on the calculator twice.
3. Choose SET UP PROBES from the MAIN
MENU. Enter 1 as the number of probes. On the
SELECT PROBES menu, choose TEMPERATURE. Enter 1 as the channel number.
4. Select USE STORED from the CALIBRATION
MENU.
5. From the MAIN MENU, select COLLECT
DATA. Select TIME GRAPH from the DATA
COLLECTION MENU. Enter 15 as the time
(in s) between samples and enter 60 as the
number of samples. The CBL unit will collect
data for 15 minutes.
22
7.
400-mL beaker and place the beaker on the hot
plate. Turn on the hot plate and heat the water to
approximately 90°C.
Using a laboratory balance, measure the mass of
an empty test tube and record the value in Data
Table 1. Add about 8.0 g of BHT to the test tube.
Measure the total mass of the test tube and BHT
and record the measurement.
Use the clamp to suspend the test tube in the hot
water bath. After the BHT has melted completely,
reposition the clamp so the test tube is not over
the hot water bath or the hot plate. Place the temperature probe into the BHT mixture and press
ENTER on the calculator to begin collecting data.
To maintain even cooling, stir the BHT continuously using the copper wire stirrer.
After the data collection is complete, make a
graph by transferring the data to a computer using
the directions from page v.
Using the same BHT sample, add about 1.0 g of
para-dichlorobenzene (PDB) to the test tube.
Record the mass in Data Table 1. Repeat steps
3–5 above. Be sure to stir the solution once it has
all melted.
Repeat steps 1–6 using a clean test tube, about
8.0 g of BHT, and about 1.0 g of the unknown.
Be sure the two substances are well mixed during
the melting phase.
Cleanup and Disposal
1. Dispose of or store the chemical as directed by
your teacher.
2. Rinse the probes with distilled water. Dispose of
the rinse water in an appropriate container.
3. Clean up lab tables and wash your hands with
soap or detergent before leaving the lab.
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
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Data and Observations
Data Table 1
Substance
Mass (g)
Empty test tube 1
Test tube 1 BHT
Test tube 1 BHT PDB
BHT
PDB
Empty test tube 2
Test tube 2 BHT
Test tube 2 BHT unknown
BHT
Unknown
Calculate the masses of the BHT, PDB, and unknown substance.
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Analyze and Conclude
1. Observing and Inferring Using the graphs, determine the melting point for each of the
following: pure BHT; BHT PDB; BHT unknown.
2. Collecting and Interpreting Data
a. What is the difference in freezing point between pure BHT and the solution of BHT
and PDB?
b. What is the difference in freezing point between pure BHT and the solution of BHT
and the unknown?
3. Measuring and Using Numbers Calculate the molality of the solution of BHT and
PDB (in mol solute/kg solvent).
Chemistry CBL Laboratory Manual
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4. Measuring and Using Numbers Calculate the freezing point depression constant Kf for
BHT. (Tf Kf m)
5. Thinking Critically Why was a solvent with a large Kf value used in this activity?
6. Error Analysis Calculate the molecular mass of the unknown and compare it to the
Real-World Chemistry
1. How does antifreeze help cars in both the
winter and the summer?
24
2. Why do road crews in snowy climates keep a
supply of CaCl2 on hand? Explain why CaCl2
works better than NaCl.
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
actual molecular mass provided by your teacher. Calculate the percent error of the
experimentally determined molecular mass.
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CHEMISTRY CBL LABORATORY MANUAL
Calorimetry
H
eat is energy that is being transferred from a hot object to a
colder object. If you know how much heat a substance can
absorb and hold, the amount of energy transferred between two
substances can be determined. On a hot, sunny day, heat from the
Sun might go into a cool glass of lemonade and melt the ice. On a
cold winter day, heat may leave a hot cup of coffee and warm up the
air around it. In this lab, specific heat is used to follow the flow of
energy and to determine the temperature of a Bunsen burner flame.
Problem
Objectives
Materials
What is the temperature of
a Bunsen burner flame?
• Diagram a flowchart
that depicts the flow
of energy in this
experiment.
• Calculate the amount of
energy transferred
between two systems.
CBL unit
TI graphing
calculator
link cable
AC adapter
temperature probe
nickel coin
100-mL graduated
cylinder
Bunsen burner
large plastic-foam
cup
tongs
matches
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Safety Precautions
• Always wear safety goggles and a lab apron.
• Be careful when working with an open flame, and tie back long hair.
• Once the nickel is heated, the tongs will be hot. Do not touch them.
Pre-Lab
Procedure
1. What is the difference between heat and
Part A: Preparing the CBL System
2.
3.
4.
5.
temperature?
What is meant by specific heat? What is the
specific heat of water? Of nickel?
What equation can be used to calculate the
amount of heat transferred between two
substances?
How much energy (in cal) would it take to raise
the temperature of 5.00 g of water from 20°C to
30°C?
Read the entire laboratory activity. Sketch a
diagram to show the flow of heat.
Chemistry CBL Laboratory Manual
1. Connect the CBL unit to the temperature probe,
as shown in Figure A. Make sure the temperature
probe is in channel 1. Then, using a link cable,
connect the CBL unit to the graphing calculator.
2. Turn on the CBL unit and the graphing calculator.
Press the PRGM button on the calculator and
choose ChemBio from the list of programs. Press
ENTER on the calculator twice.
3. Choose SET UP PROBES from the MAIN
MENU. Enter 1 as the number of probes. On the
SELECT PROBES menu, choose TEMPERATURE. Enter 1 as the channel number.
25
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CHEMISTRY CBL LABORATORY MANUAL
4. Using tongs, hold the nickel in the Bunsen
Figure A
TI graphing
calculator
CBL
unit
Temperature
probe
5.
6.
7.
AC adapter
Link cable
4. From the MAIN MENU, select COLLECT
DATA. On the DATA COLLECTION menu,
select MONITOR. Do NOT press ENTER until
you are ready to monitor the temperature.
8.
burner flame until it glows red. This should take
3–5 min. If the nickel has been used previously,
it may not glow red.
Now press ENTER on the graphing calculator to
begin monitoring temperature.
Place the temperature probe in the water in the
cup. Read the temperature and record the initial
temperature of the water in Data Table 1.
Leave the temperature probe in the water.
Quickly, but carefully, take the nickel out of the
flame and drop it in the water. CAUTION: Do
not allow the hot nickel to touch the sides of
the cup. Carefully stir the water with the temperature probe and monitor the temperature. Record
in Data Table 1 the highest temperature that the
water reaches.
Pour out the water and the nickel into the sink.
Repeat steps 1–7 using 60 mL of water and again
using 80 mL of water.
Part B: Collecting Data
water and pour it into the cup.
2. Determine the mass of your nickel and record it
in Data Table 1.
3. Turn on the gas and light the Bunsen burner.
Create as hot a flame as possible. CAUTION: Be
careful when working with an open flame, and
tie back long hair.
Cleanup and Disposal
1. Make sure the gas to the Bunsen burner is shut
off completely.
2. Turn off and unplug the CBL unit.
3. Return all equipment to its proper place. Clean up
the lab area.
Data and Observations
Data Table 1
Trial
26
Mass of
nickel (g)
Volume of
water (mL)
Initial
temperature
of water (°C)
Final
temperature
of water (°C)
Change in
temperature
of water, or T (°C)
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
1. Using a graduated cylinder, measure 40 mL of tap
Name
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CHEMISTRY CBL LABORATORY MANUAL
Analyze and Conclude
1. Using Numbers For each trial, determine the change in the water temperature, T, and
record it in Data Table 1. (T Tfinal Tinitial)
2. Observing and Inferring How much energy (in cal) was absorbed by the water in each
trial? How do your three results compare? (Specific heat of water is 1.00 cal/g°C.)
Assume the density of water is 1.00 g/mL.
3. Thinking Critically How much heat did the nickel lose in each trial?
4. Drawing a Conclusion Using the information from questions 2 and 3, what is the
temperature of the Bunsen burner flame?
5. Communicating Post your data on the board and compare it with the class data. What is
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
the average temperature calculated by your class for the Bunsen burner flame?
6. Error Analysis Compare your Bunsen burner flame temperature with the actual
temperature that your teacher gives you. How close were you? What might have been
some sources of error in this lab? What assumptions were made that may have caused
errors in your numbers?
Real-World Chemistry
1. Why might it be effective for homeowners to
use a water-heater blanket around the water
heaters in their homes?
Chemistry CBL Laboratory Manual
2. How is a thermos bottle able to keep hot
liquids hot and cold liquids cold?
27
Name
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Class
CHEMISTRY CBL LABORATORY MANUAL
Hess’s Law
H
ess’s law states that the heat gained or released in a chemical
reaction is the sum of the heat gained or released during the
individual steps of that reaction. In this lab, you will determine the
molar enthalpy of reaction (Hrxn) for three chemical reactions. Then,
you will use Hess’s law to verify the experimental value obtained for
one of these reactions.
Problem
Objectives
Materials
How can the enthalpy
changes for two chemical
reactions be used to obtain
the enthalpy change for
the reaction of ammonia
with hydrochloric acid?
NH3(aq) HCl(aq) 0
NH4Cl(aq)
• Measure the heat
absorbed or released in
three chemical reactions.
• Determine the molar
enthalpy of each
reaction.
• Apply Hess’s law to verify
one of the experimental
results.
CBL unit
TI graphing
calculator
link cable
AC adapter
temperature probe
2.0M HCl
2.0M NH4Cl
Is this an exothermic or
endothermic reaction?
2.0M NaOH
2.0M NH3(NH4OH)
100-mL graduated
cylinders (2)
thermometers (2)
large plastic-foam
cup
glass stirring rod
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Safety Precautions
• Always wear safety goggles and a lab apron.
• Use caution when working with acids and bases.
• The reaction of ammonium chloride and sodium hydroxide releases
ammonia; the reaction should be performed in an operating fume
hood.
Pre-Lab
1. Read the entire laboratory activity. Describe
Hess’s law in your own words.
2. Describe how specific heat is used in calorimetry.
3. Describe in your own words what is meant by H.
Procedure
Part A: Preparing the CBL System
1. Connect the CBL unit to the temperature probe,
as shown in Figure A. Plug the adapter cable
into channel 1 of the CBL unit and then plug
a temperature probe into the adapter cable. Make
sure the temperature probe is in channel 1.
Chemistry CBL Laboratory Manual
Then, using a link cable, connect the CBL unit to
the graphing calculator.
2. Turn on the CBL unit and the graphing calculator.
Press the PRGM button on the calculator and
choose ChemBio from the list of programs. Press
ENTER on the calculator twice.
3. Choose SET UP PROBES from the MAIN
MENU. Enter 1 as the number of probes. On the
SELECT PROBES menu, choose TEMPERATURE. Enter 1 as the channel number. Select
USE STORED from the CALIBRATION MENU.
29
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8
CHEMISTRY CBL LABORATORY MANUAL
6. Pour the HCl solution into the cup and insert
Figure A
Adapter cable
CBL
unit
TI graphing
calculator
7.
Temperature
probe
8.
Plastic-foam cup
Link cable
9.
Part B: Collecting Data
1. For reaction 1, measure 50 mL of 2.0M HCl in
2.
3.
4.
5.
30
a 100-mL graduated cylinder. Measure 50 mL
of 2.0M NaOH in a second 100-mL graduated
cylinder.
From the MAIN MENU, select COLLECT
DATA. On the DATA COLLECTION MENU,
select TIME GRAPH. Enter 30 as the time
(in s) between samples and then enter 3 as the
number of samples. The CBL unit will collect
data for 4 min.
Press ENTER, then select USE TIME SETUP
to continue. Note: If you want to change the
sample time or sample number you entered,
select MODIFY SETUP.
Enter 0 as the minimum temperature (Ymin) and
enter 50 as the maximum temperature (Ymax).
Enter 1 as the temperature increment (Yscl). Do
not hit ENTER to begin collecting data yet.
Using two thermometers, measure the initial
temperatures of the two solutions and record
them in Data Table 1. If the two initial temperatures are less than 0.2°C apart, average the two
temperatures and use the average as the initial
temperature.
10.
11.
the temperature probe from the CBL unit. Press
ENTER to begin taking data. Then, cautiously
pour the NaOH solution into the cup while
stirring with a glass stirring rod.
Have the CBL unit take data every 30 s for
4 min as the reaction continues. Continue to stir
the solution slowly and monitor the CBL unit
and calculator. If your calculator has a sleep
function, be sure to press a number button
occasionally to keep it from shutting off.
When the CBL unit has stopped taking data,
turn the CBL unit off and download the data
from the graphing calculator to the computer,
following the instructions in Appendix A. Save
your data.
Using distilled water, thoroughly rinse the thermometers and wash out the graduated cylinders.
Repeat steps 1–8 for reaction 2 using 50 mL of
2.0M NH4Cl with 50 mL of 2.0M NaOH.
Thoroughly rinse the thermometers and graduated cylinders again with distilled water and
repeat steps 1–8 for reaction 3 using 50 mL of
2.0M NH3 with 50 mL of 2.0M HCl.
Download the data from the calculator to a
computer after each trial and save the data.
Cleanup and Disposal
1. Wash all solutions down the drain with plenty
2.
3.
4.
5.
of water.
Rinse the graduated cylinders.
Rinse the probes with distilled water.
Turn off the CBL unit and unplug it.
Return all equipment to its proper place, clean
up the lab area, and wash your hands with soap
or detergent.
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
LAB
Class
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CHEMISTRY CBL LABORATORY MANUAL
Data and Observations
Data Table 1
Reaction
Initial temperature
before mixing (Tinitial)
Temperature directly after mixing
(Tmix), derived from graph
1
2
3
Analyze and Conclude
1. Making and Using Graphs Make a graph of the data from each of the three trials. Plot
time (s) on the x-axis and temperature (°C) on the y-axis.
2. Acquiring and Analyzing Information Draw a best fit line through your data. The line
should intercept the y-axis. The point at which the line intercepts the y-axis is the
temperature directly after mixing (Tmix). Record Tmix in Data Table 1.
3. Measuring and Using Numbers Assume the density of the mixed solutions is
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
1.03 g/mL. Assume that the specific heat of the solutions is the same as the specific heat
of water, 4.18 J/g°C. Using the following equations, determine the enthalpy change for
each reaction.
a. Tsolution Tmix Tinitial
b. qreaction (grams of solution specific heat of solution Tsolution)
4. Measuring and Using Numbers What is the molar enthalpy for each of the three
reactions in kJ/mol?
Chemistry CBL Laboratory Manual
31
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CHEMISTRY CBL LABORATORY MANUAL
5. Observing and Inferring Rearrange the equations for reactions 1 and 2 to obtain the
equation for reaction 3. Determine the change in enthalpy for reaction 3. Compare this
result with the enthalpy change you obtained by direct measurement.
6. Classifying Classify reactions 1, 2, and 3 as exothermic or endothermic.
7. Error Analysis Every measurement involves a certain amount of error. Which of the
two values for H for reaction 3 is likely to have the greater error? What is the largest
source of error in this lab?
Real-World Chemistry
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Explain how cold packs and hot packs work.
32
Chemistry CBL Laboratory Manual
Name
LAB
Date
9
Class
CHEMISTRY CBL LABORATORY MANUAL
Determine the Molar Mass
of an Unknown Acid
A
ccording to the Arrhenius definition of acids and bases, acids are
substances that produce hydrogen ions (H) in solution, and
bases are substances that produce hydroxide ions (OH) in solution.
When an acid and a base combine, the hydrogen ions from the acid
react with the hydroxide ions from the base to form water—a
neutralization reaction.
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
In a neutralization reaction, moles of H ions equal moles of OH
ions. This relationship is the basis for the procedure called titration,
which you will use to standardize a base solution. Standardizing a
base means determining its molar concentration. You will then use
your standardized base to determine the molar mass of an acid. To
determine when the moles of H equal the moles of OH, you will
monitor the pH of an acid solution as a solution of base is added
slowly. The pH will rise suddenly when the concentrations of the two
ions are equal (the equivalence point).
Problem
Objectives
Materials
What is the molar mass of
an unknown acid?
• Standardize a sodium
hydroxide solution.
• Determine the molar
mass of an unknown acid
using titration data.
CBL unit
pH probe
TI graphing
calculator
link cable
potassium hydrogen
phthalate (KHP)
NaOH solution
unknown acid
phenolphthalein
solution
250-mL beakers (2)
250-mL Erlenmeyer
flask
50-mL burette
wash bottle with
distilled water
funnel
ring stand
weighing paper or
dish
microspatula or
scoop
balance, sensitive
burette clamp
utility clamp
Safety Precautions
• Always wear safety goggles and a lab apron.
• Use caution when working with acids and bases.
• Wipe up any water spills to avoid slipping.
Chemistry CBL Laboratory Manual
33
Name
LAB
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9
Class
CHEMISTRY CBL LABORATORY MANUAL
Pre-Lab
Figure A
pH probe
1. Define the following terms: (a) acid, (b) base,
(c) neutralize, (d) titration, and (e) pH.
2. Write a balanced equation for the dissociation of
(a) HCl, (b) H2SO4, (c) NaOH, (d) Mg(OH)2
3. Read the entire laboratory activity. Write
the balanced chemical equation for each of the
following:
a. hydrochloric acid (HCl) reacts with sodium
hydroxide (NaOH)
b. sulfuric acid (H2SO4) reacts with sodium
hydroxide (NaOH)
Burette
Graphing
calculator
Burette
clamp
CBL
unit
Ring
stand
Erlenmeyer
flask
Procedure
5. Using a weighing dish, measure 0.4–0.6 g of
1. Connect the CBL unit to the pH probe. Make sure
the pH probe is in channel 1. Then, using a link
cable, connect the CBL to the graphing calculator.
2. Turn on the CBL unit and the graphing calculator.
Press the PRGM button on the calculator and
choose ChemBio from the list of programs. Press
ENTER on the calculator twice.
3. Choose SET UP PROBES from the MAIN
MENU. Enter 1 as the number of probes. On the
SELECT PROBES menu, choose pH. Enter 1 as
the channel number. Select USE STORED from
the CALIBRATION MENU.
Part B: Standardizing NaOH
6.
7.
8.
1. Set up the burette, burette clamp, 250-mL
Erlenmeyer flask, the CBL, and pH probe for
titration as shown in Figure A.
2. Pour about 70 mL of NaOH solution into a
250-mL beaker.
3. Using a funnel, carefully fill the burette to the
zero line with the NaOH solution.
4. To eliminate any air in the burette tip, allow a
little of the NaOH solution to run through the tip
into a 250-mL waste beaker. Then refill the
burette to the zero line.
34
9.
10.
potassium hydrogen phthalate (KHP). Record
the mass of KHP in Data Table 1. Transfer the
KHP to a 250-mL Erlenmeyer flask. With a
wash bottle filled with distilled water, rinse any
residue from the weighing dish into the flask.
Add about 40 mL of distilled water to the
Erlenmeyer flask and swirl until the solid KHP
is completely dissolved. Then add 3 drops of
phenolphthalein to the acid in the flask.
From the MAIN MENU, select COLLECT
DATA. On the DATA COLLECTION MENU,
select TRIGGER PROMPT. Follow the directions on the calculator to collect data.
Insert the pH probe into the KHP solution.
When the pH meter is stable, press TRIGGER
on the CBL unit.
The calculator will read VALUE? Enter 0 for
the volume of NaOH that has been added. This
will give you the initial pH value.
From the DATA COLLECTION MENU, select
MORE DATA. Add 1 mL of NaOH from the
burette to the Erlenmeyer flask while swirling.
After the pH has stabilized once more, press
TRIGGER on the CBL unit and enter 1 for the
number of mL of NaOH added. Always enter
the total volume of NaOH that has been added
to the Erlenmeyer flask.
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Part A: Preparing the CBL System
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CHEMISTRY CBL LABORATORY MANUAL
11. Continue to add the NaOH solution 1 mL at a
12.
13.
14.
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
15.
Class
time and take pH readings after each addition,
until the pH begins to change. Then, add the
NaOH solution by 0.5 mL and finally, by
1-drop increments until the pH rises quickly.
This is the equivalence point. Record in Data
Table 1 the total volume of NaOH used at this
point.
After you have reached the equivalence point,
add a few more mL of NaOH, making pH
measurements after every 1 mL addition. If no
more change occurs, the titration is complete.
Note the color of the solution in the beaker.
Download your data to the computer following
the procedure in Appendix A.
Rinse the 250-mL Erlenmeyer flask. Repeat
steps 2–13 as many times as your teacher
directs.
Use your data to calculate the concentration of
the NaOH. Use the class average of this concentration for Part C of this activity.
Part C: Titrating an Unknown Acid
1. Fill the burette to the zero line with your stan-
dardized NaOH solution.
2. Using a clean weighing dish, measure 0.3–0.4 g
of the unknown acid into a 250-mL Erlenmeyer
flask. Rinse any residue into the flask. Record the
mass in Data Table 2.
3. Dissolve the unknown acid in about 40 mL of
distilled water. Swirl to completely dissolve the
acid.
4. Titrate the unknown acid following the procedure
described in steps 2–13 of Part B. Record the volume of NaOH solution in Data Table 2.
Cleanup and Disposal
1. Rinse the beakers and Erlenmeyer flask with
plenty of water.
2. If not being used again, empty the burettes and
clean them according to your teacher’s directions.
3. Disconnect the pH sensor and TI graphing calculator from the CBL unit. Following your teacher’s
directions, return all equipment to its proper
place.
Data and Observations
Data Table 1: Standardization of Base (Molar Mass of KHP 204.2 g/mol)
Mass of KHP
Mol KHP
Volume of NaOH (L)
Mol NaOH
Concentration
of NaOH (mol/L)
Data Table 2: Molar Mass of Unknown Acid
Volume of
NaOH (L)
Concentration
of NaOH (mol/L)
Chemistry CBL Laboratory Manual
Mol NaOH
Mol of
unknown acid
Mass of
unknown acid (g)
Molar mass
of unknown
acid (g/mol)
35
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CHEMISTRY CBL LABORATORY MANUAL
Analyze and Conclude
1. Measuring and Using Numbers KHP has one ionizable H ion per mole of KHP.
What is the ratio of moles of NaOH to moles of KHP in this reaction?
2. Measuring and Using Numbers Determine the concentration of the NaOH solution and
record it in the appropriate space in Data Table 1.
3. Acquiring and Analyzing Information In Part C, how many moles of NaOH did it
take to neutralize the unknown acid? Your teacher will tell you how many ionizable hydrogen atoms are in your unknown acid. What is the molar ratio of acid to base for this
reaction? What is the molar mass of the unknown acid?
4. Error Analysis Your teacher will give you the molar mass of the unknown acid.
Determine your percent error for this experiment.
concentration of the NaOH solution compare to the actual concentration?
a. The mass of the acid was measured correctly, but some of it was spilled on the counter
when transferring it to the Erlenmeyer flask.
b. Although not noticed, some of the NaOH was spilled on the counter, instead of going
into the flask with the acid.
Real-World Chemistry
1. Why is it important to monitor the pH levels of
lakes, ponds, rivers, and streams?
36
2. Name some common antacids and describe
what ingredients make them work. How do
they help upset stomachs?
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
5. Error Analysis If the following errors occurred, how would your calculated
Name
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Class
CHEMISTRY CBL LABORATORY MANUAL
Reaction Potentials of Metals
A
voltaic cell is a device that converts chemical energy to electrical
energy. This is done by harnessing the electron flow generated by
a spontaneous redox reaction. A voltaic cell consists of two half-cells
connected by a conducting wire and a salt bridge. One half-cell, called
the anode, contains a metal in a solution of its ions and is the site of
oxidation. The other half-cell, called the cathode, contains a different
metal in a solution of its ions and is the site of reduction. The
conducting wire carries the flow of electrons. The salt bridge allows ions
to flow from one side to the other so the redox reaction can continue.
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
In this lab, a voltage probe is used to measure the flow of electrons
through voltaic cells made of different metals. The metal attached to
the positive lead of the voltage probe is the cathode and has a higher
reduction potential. The metal attached to the negative lead is the
anode and has a lower reduction potential. The reduction potentials of
five metals will be compared, resulting in a chart for understanding the
potentials of metals.
Problem
Objectives
Materials
Rank a series of different
metals from lowest reduction potential to highest
reduction potential. How
can the cell potential for
two half-reactions be
calculated?
• Measure the amount
of current flowing
between two half-cells
of a reaction.
• Predict the cell potentials
of a two-metal system.
• Analyze the data in
order to rank the metals
from a high reduction
potential to low
reduction potential.
CBL unit
TI graphing
calculator
voltage probe
link cable
adapter cable
1M solution of each
of the following:
sodium nitrate
(NaNO3)
copper sulfate
(CuSO4)
zinc sulfate
(ZnSO4)
lead nitrate
(Pb(NO3)2)
silver nitrate
(AgNO3)
iron sulfate
(FeSO4)
1 1-cm pieces of
the following
metals:
copper
zinc
lead
silver
iron
large watch glass
forceps
scissors
sandpaper
filter paper
Safety Precautions
• Always wear safety goggles and a lab apron.
• Use caution with sharp edges of metals.
• AgNO3, CuSO4, Pb(NO3)2, and FeSO4 are toxic by ingestion; ZnSO4 and
Pb(NO3)2 may cause skin and eye irritation; AgNO3 will stain skin and
clothes.
• Use forceps to handle the metals.
Chemistry CBL Laboratory Manual
37
Name
LAB
Date
10
Class
CHEMISTRY CBL LABORATORY MANUAL
Pre-Lab
Cut along
dotted lines
Figure A
1. Read over the entire laboratory activity. Define
2.
3.
4.
5.
reduction and oxidation.
Write the half-reaction for (a) the oxidation of
zinc; (b) the reduction of copper.
What happens at the anode? What happens at the
cathode?
In which direction do electrons flow in a voltaic
cell?
Review the equation to calculate the potential of
a voltaic cell.
Pb
Zn
Ag
NaNO3
solution
Procedure
Cu
Part A: Preparing the CBL System
Fe
1. Connect the CBL unit to the voltage probe. Plug
Part B: Data Collecting
1. Obtain a 1 1-cm piece of each of the following
metals: copper, zinc, lead, silver, and iron. Also
obtain dropper bottles with 1M solutions of copper sulfate (CuSO4), zinc sulfate (ZnSO4), lead
nitrate (Pb(NO3)2), silver nitrate (AgNO3), and
iron sulfate (FeSO4)
2. Set up the equipment for the investigation. Draw
dashed lines on the filter paper, as indicated in
Figure A. Cut out the triangular areas between
the dashed lines and place the filter paper on top
of the watch glass.
38
Filter paper
3. Label the ends of the filter paper with the metal
4.
5.
6.
7.
strips to be tested (See Figure A).
Place several drops of NaNO3 solution in the
middle of the paper with trails of this NaNO3
solution leading out to each end of the paper. If
the NaNO3 center and trails begin to dry out,
reapply the NaNO3 solution throughout the
activity.
Next, place 3 drops of the metal ion solutions on
the corresponding areas of the filter paper (indicated by the name of the metal).
Using tongs, place the corresponding metal piece
on top of the solution. Always keep the top of the
metal dry. Note: If the metal has oxidized, shine
it with sandpaper first.
Using copper as a reference metal, compare the
potential of the other four metals with that of
copper. To do this, place the positive lead of the
voltage probe on copper and the negative lead on
the metal being tested. If the voltage reads negatively, reverse the leads. Wait about 5 s and
record the voltage of each of the metals compared
with copper in Data Table 1. Test the following
combinations: Cu and Zn, Cu and Pb, Cu and Ag,
and Cu and Fe.
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
the adapter cable in channel 1 and then plug the
voltage probe into the adapter cable. Using a link
cable, connect the CBL unit to the graphing calculator.
2. Turn on the CBL unit and the graphing calculator.
Press the PRGM button on the calculator and
choose ChemBio from the list of programs. Press
ENTER on the calculator twice.
3. Choose SET UP PROBES from the MAIN
MENU. Enter 1 as the number of probes. On the
SELECT PROBE MENU, choose VOLTAGE.
Enter 1 as the channel number. Select COLLECT
DATA from the MAIN MENU.
4. From the DATA COLLECTION menu, select
MONITOR INPUT. The voltage reading is now
displayed on the screen. No readings will be
stored in the MONITOR INPUT mode.
Name
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CHEMISTRY CBL LABORATORY MANUAL
8. Because copper was the reference metal, assign
it an arbitrary reduction potential of zero. Rank
the metals in order of lowest reduction potential
(most negative) to highest reduction potential
(most positive) in Data Table 2. If the test
metal was connected to the negative lead, then
the voltage should be listed above copper and
given a negative value. If the test metal was
connected to the positive lead, then the voltage
should be listed below copper and assigned a
positive value.
9. Before experimenting further, predict the potential for the combinations given in Data Table 3.
Use the information from Data Table 2 to make
your predictions. Determine the actual potentials of these combinations of metals.
Remember to keep the voltage positive and
keep the NaNO3 moist.
10. Test the following combinations: Zn and Pb, Zn
and Ag, Zn and Fe, Pb and Ag, Pb and Fe, and
Ag and Fe.
Cleanup and Disposal
1. Dispose of silver and lead products in waste
containers designated by your teacher.
2. Place all metal pieces in a solid-waste container.
3. Throw away filter paper and clean up the lab
area. Wash your hands before leaving the lab.
4. Disconnect the sensor from the CBL unit. Turn
off the CBL unit and graphing calculator,
unplug them, and return all equipment to its
proper place.
Data and Observations
Data Table 1
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Metals used
Data Table 2
Voltage
Metal
Reduction potential
(lowest to highest)
Cu/Zn
Cu/Pb
Cu/Ag
Cu/Fe
Data Table 3
Metal
Predicted potential
Measured potential
Percent error
Zn/Pb
Zn/Ag
Zn/Fe
Pb/Ag
Pb/Fe
Ag/Fe
Chemistry CBL Laboratory Manual
39
Name
Date
LAB
10
Class
CHEMISTRY CBL LABORATORY MANUAL
Analyze and Conclude
1. Collecting and Interpreting Data Which metal in this experiment loses electrons most
readily? Which element gains electrons most readily?
2. Observing and Inferring How do your answers in question 1 help explain the data that
were recorded during this lab?
3. Formulating Models Sketch a diagram of the flow of electrons for one of the voltaic cells
4. Thinking Critically What is the function of the NaNO3-soaked filter paper?
5. Error Analysis What may have caused any errors found in this lab?
Real-World Chemistry
1. How do lead storage batteries produce an
electric current?
40
2. Look up a reference table of reduction poten-
tials. Why might they differ from your values?
Chemistry CBL Laboratory Manual
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
made in the lab. Be sure to label the electrons, reduction, oxidation, cathode, and anode.