Glencoe chemistry CBL lab manual 0078245303

The activities in the 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 d

CBL Laboratory ManualStudent Edition

Hands-On Learning:

Laboratory Manual, SE/TE

Forensics Laboratory Manual, SE/TE

CBL Laboratory Manual, SE/TE

Small-Scale Laboratory Manual, SE/TE

ChemLab and MiniLab Worksheets

Review/Reinforcement:

Study Guide for Content Mastery, SE/TE

Solving Problems: A Chemistry Handbook

Reviewing Chemistry

Guided Reading Audio Program

Applications and Enrichment:

Section Focus Transparencies and Masters Math Skills Transparencies and Masters Teaching Transparencies and Masters Solutions Manual

Technology:

Chemistry Interactive CD-ROM Vocabulary PuzzleMaker Software, Windows/MacIntosh

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Copyright © by The McGraw-Hill Companies, Inc.

All rights reserved Permission is granted to reproduce the material contained herein

on the condition that such material be reproduced only for classroom use; be provided

to students, teachers, and families without charge; and be used solely in conjunction

with the Chemistry: Matter and Change program Any other reproduction, for use or

sale, is prohibited without prior written permission of the publisher.

Send all inquiries to:

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

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

Contents

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 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

Organization of Activities

• 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

hypoth-esis for this activity

• Data and ObservationsThis section presents a suggested table or form for

collecting your laboratory data Always record data and observations in an

organ-ized 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

conclu-sions 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

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,

double-click 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

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

CBL unit TI-83 calculator

Link cable

AC adapter

Syringe

Gas pressure sensor DIN adapter

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

1 The chemistry laboratory is a place for serious

work Do not perform activities without your

teacher’s permission Never work alone in the

lab-oratory Work only when your teacher is present

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

tubes, paper, or beakers to obtain your chemicals

Take only small amounts It is easier to get morethan 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 areprohibited in the laboratory

15 If chemicals come into contact with your eyes or

skin, flush the area immediately with large ties of water Immediately inform your teacher ofthe nature of the spill

quanti-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 whensuch 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 glasslooks the same as cool glass

20 Dispose of broken glass, unused chemicals, and

products of reactions only as directed by yourteacher

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 surethe gas and water are turned off Wash your handswith soap and water before you leave the lab

This symbol appears when substances could stain or burn clothing.

Animal Safety

This symbol appears when safety of animals and students must

be ensured.

Radioactivity

This symbol appears when radioactive materials are used.

Avoid skin contact with these materials.

Wear mask or gloves.

Notify your teacher if you suspect contact with material Wash hands thoroughly.

Organisms or other biological materials that might be harmful to humans

bacteria, fungi, blood, unpreserved tissues, plant materials

BIOLOGICAL

Use proper protection when handling.

Go to your teacher for first aid.

Objects that can burn skin by being too cold or too hot

boiling liquids, hot plates, dry ice, liquid nitrogen

EXTREME

TEMPERATURE

Do not dispose of these materials in the sink or trash can.

Dispose of wastes as directed by your teacher.

Special disposal cedures need to be followed.

pro-certain chemicals, living organisms

DISPOSAL

SAFETY SYMBOLS

Practice sense behavior and follow guidelines for use of the tool.

common-Go to your teacher for first aid.

Use of tools or glassware that can easily puncture or slice skin

razor blades, pins, scalpels, pointed tools, dissecting probes, broken glass

Possible danger to respiratory tract from fumes

ammonia, acetone, nail polish remover, heated sulfur, moth balls

FUME

Double-check setup with teacher Check condition of wires and apparatus.

Do not attempt to fix electrical problems.

Notify your teacher immediately.

Possible danger from electrical shock or burn

improper grounding, liquid spills, short circuits, exposed wires

ELECTRICAL

Wear dust mask and gloves Practice extra care when handling these materials.

Go to your teacher for first aid.

Substances that can irritate the skin or mucus membranes of the respiratory tract

pollen, moth balls, steel wool, fiber glass, potassium permanganate

IRRITANT

Wear goggles, gloves, and an apron.

Immediately flush the affected area with water and notify your teacher.

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

Substance may be poisonous if touched, inhaled, or swallowed

mercury, many metal compounds, iodine, poinsettia plant parts

Notify your teacher immediately Use fire safety equipment if applicable.

Open flame may ignite flammable chemicals, loose clothing, or hair

alcohol, kerosene, potassium permanganate, hair, clothing

OPEN FLAME

The Chemistry: Matter and Change program uses safety symbols to alert you and your students to possible

laboratory dangers These symbols are provided in the student text in Appendix B and are explained below

Be sure your students understand each symbol before they begin an activity that displays a symbol

• 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.

Problem

How many observations

can you make about a

reaction? Are your

• Predict one product

produced during thereaction

Materials

CBL unit

TI graphing calculatorlink cabletemperature probecopper(II) chloride

2  2-in square ofaluminum foil

150-mL beaker100-mL graduatedcylinder

microspatulaglass stirring rodpaper towelmagnifying glassweighing paper

Reactions 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

Pre-Lab

1. What is the difference between observations and

interpretations?

2. Give three examples of qualitative observations

and three examples of quantitative observations

3. What are some tools that scientists use to enhancetheir observational techniques?

Part A: Preparing the CBL System

1. Connect the CBL unit to the temperature probe,

as shown in Figure A Make sure the

tempera-ture 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

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.

4. Using the 100-mL graduated cylinder, obtain

50 mL of distilled water Pour the water into the150-mL beaker

5. Place the temperature probe in the water

Record an initial temperature of the water bypressing TRIGGER on the CBL unit Followdirections on the calculator to continue collecting data

6. With the temperature probe in the water, fer the copper(II) chloride into the waterwithout touching the probe Try not to agitatethe mixture Note any temperature change

trans-7. Before stirring the mixture, record as many

observations as possible in Data Table 1.

8. Using the glass stirring rod, stir the mixture

After stirring, make and record as many vations as possible

obser-9. Roll the aluminum foil loosely into a ball Donot tightly pack the aluminum Place the foilball in the copper(II) chloride mixture Let thereaction proceed for about 15 min Make andrecord as many observations as possible of thereaction mixture

10. Record the maximum temperature change thattakes place during the reaction

11. When the reaction appears to be complete,remove the probe from the water Pour off asmuch of the liquid as possible

12. Label a paper towel with your name and classperiod Pour the remaining contents onto thepaper towel Set aside the paper towel forobservation on the second day of lab

Cleanup and Disposal

1. Disconnect the temperature probe from theCBL unit

2. After emptying the beaker, clean and rinse thebeaker Rinse the probe with distilled water andcarefully wipe it dry

3. Return all equipment to its proper place

4. Clean up the lab area and wash your hands withsoap or detergent before leaving the lab

CBL unit

Figure A

Data and Observations

Analyze and Conclude

1 Observing and Inferring Describe the events that took place that provide evidence for 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?

5. Initial temperature of water (°C)

7. Copper(II) chloride and water mixture

1. Why is it important for scientists to have

as much data as possible before making

interpretations?

2. Why is important for high school students to

develop their observation skills?

3. How do observation and interpretation skillshelp when working with the scientific method?

Real-World Chemistry

• 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.

Problem

How can an electric current

be used to determine the

extent to which solid

sub-stances dissolve in water?

Objectives

• Predict what substances

will dissociate in waterbased on their chemicalmakeup

• Write balanced equations

for the dissociation of substances in water

• Compare the conductivity

Materials

CBL unit

TI graphing calculatorcomputerlink cableconductivity probeadapter cabledropper bottles (3)with:

(a) 1M NaCl (b) 1M MgCl2(c) 1M AlCl3

50-mL beakers (2)with:

(a) NaCl(b) sugar(C12H22O11)

400-mL beaker150-mL beakers (3)100-mL graduatedcylinder

glass stirring rodring stand withtest-tube clampwash bottle of distilled watermicrospatulaelectronic balanceweighing dishes (2)plastic beral

pipettes (3)

The 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

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

1. Read over the entire laboratory activity Write

balanced chemical equations for the dissociation

of NaCl, MgCl2and AlCl3in 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

con-sidered 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

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

4. Turn on the CBL unit and the graphing calculator.Choose ChemBio from the list of programs PressENTER on the calculator twice

5. Choose SET UP PROBES from the MAINMENU Enter 1 as the number of probes On theSELECT PROBES menu, choose CONDUCTIV-ITY Enter 1 as the channel number Then selectUSE STORED from the CALIBRATION menuand select H 0-2000 MICS from the CONDUC-TIVITY menu Make sure the switch on the box

is set to the same value

6. From the MAIN MENU, select COLLECTDATA On the DATA COLLECTION menu,select TRIGGER PROMPT Allow the unit towarm up and then press ENTER

Part B: Comparing Ionic Compounds

1. Label three beral pipettes—NaCl, MgCl 2, and

AlCl 3 Fill one of the pipettes with the 1.0M

solu-tion of NaCl Fill the other two pipettes with

1.0M MgCl2and AlCl3, respectively

2. 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 inthe water After the conductivity meter stabilizes,press TRIGGER on the CBL unit

3. Measure and record the conductivity of the

dis-tilled water in Data Table 1.

4. Lower the beaker and place 1 drop of NaCl tion into the distilled water Stir with the glassstirring rod and then raise the beaker until theconductivity probe is in the solution After theconductivity meter stabilizes, press TRIGGER onthe CBL unit Measure and record the conductiv-

solu-ity of this solution in Data Table 1.

5. Adding 1 more drop of the NaCl solution, repeatstep 4 Continue adding 1 drop and recording itsconductivity until a total of 8 drops of NaCl solu-tion has been added

6. If a TI-83 graphing calculator is being used, oranother type of graphing calculator and a com-puter is available, refer to Appendix A forinstructions on how to convert this data intographical analysis

7. After transferring the data to the graphing gram, rinse out the beaker with distilled waterand repeat steps 4–6 two more times using MgCl2

Beaker

Conductivity probe

Figure A

and AlCl3, respectively Be sure to transfer the

data to the graphing program and rinse out the

beaker after each substance Rinse the

conductiv-ity 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

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

chlo-ride (NaCl) and the other beaker sucrose

(C 12 H 22 O 11 ).

3. Pour the solid sodium chloride and sucrose into

the appropriate beakers and stir with a glass

stirring rod

4. Use the conductivity probe to monitor the ductivity of the sodium chloride solution Record

con-the conductivity in Data Table 2.

5. Rinse the probe with distilled water

6. Use the conductivity probe to monitor the ductivity of the sucrose solution Record the

con-conductivity in Data Table 2.

Cleanup and Disposal

1. Disconnect the conductivity probe from the CBLunit

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

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

3 Observing and Inferring For each of the dissociation reactions of NaCl, MgCl2and

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?

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?

Real-World Chemistry

• 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.

Problem

What are the melting/

freezing points of water

and BHT (C15H24O)?

Objectives

• Describe the process of

melting and freezing

• Determine the melting

and freezing points oftwo substances

• Predict which substance

will have a higher orlower melting/freezingpoint

Materials

CBL unit

TI graphing calculatorlink cabletemperature probe

AC adapterBHT

salt (NaCl)ice

water

400-mL beaker25-mL graduatedcylinder

20  150-mm testtube

hot platering stand clampglass stirring rod

When 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

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)

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?

3. Using your textbook, look up the heating curvefor water Describe each portion of the curve andexplain why it has that particular shape

Section 13.4

Part A: Preparing the CBL System

1. Connect the CBL unit to the temperature probe,

as shown in Figure A Make sure the

tempera-ture probe is in channel 1 Then, using a link

cable, connect the CBL unit to the graphing

cal-culator

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 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

add 100 mL of water

2. 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.)

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

4. 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

5. Enter 15 as the minimum temperature (Ymin)

and 100 as the maximum temperature (Ymax)

Enter 1 as the temperature increment (Yscl)

6. Now lower the test tube of water into the beaker

of ice water and press ENTER on the calculator

to begin data collecting

7. After lowering the test tube, add 5 spoonfuls ofsalt to the beaker and stir with a stirring rod

Continue to stir the ice water

8. During data collection, slowly stir the water inthe test tube containing the temperature probe

If all the ice in the beaker melts, add additionalpieces of ice to the beaker

9. Once crystals begin to form in the water, stopstirring and let the probe freeze in the water

After 20 minutes, the CBL will stop collectingdata If you think the lab is complete before

20 minutes, you may stop the run by pressingthe <ON> button of the calculator to stop the program

10. See page v for sending data for graphical analysis

11. On the displayed graph, analyze the flat part ofthe curve to determine the freezing temperature

of water Save your data

Graphing calculator

CBL unit

Link cable

Test tube with water

or BHT

Ring stand with clamp

Temperature probe

Beaker with ice water

Figure A

Analyze and Conclude

1 Observing and Inferring What is the freezing point of water? Of BHT? What evidence

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

CBL LABORATORY MANUAL

LAB 3

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

Obtain a BHT test tube that your teacher has

pre-pared for you Repeat parts B and C using the BHT

Cleanup and Disposal

1. Dispose of the salt–ice solution following yourteacher’s directions

2. Place the BHT test tube in the hot-water bathyour teacher has prepared

3. Clean up the lab area and wash your hands withsoap or a detergent

Data and Observations

Freezing Melting Substance point (°C) point (°C)

Water BHT

Data Table 1

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?

1. How could a scientist know if he or she had

pure water or pure BHT based on the tests you

just completed?

2. Why does ice float in a glass of water?

Real-World Chemistry

• Always wear safety goggles and a lab apron.

• Use caution when pushing on syringe.

• Use caution when making electrical connections.

Problem

What is the relationship

between the volume and

pressure in a closed system?

Objectives

• Collect data that relate

pressure to volume

• Analyze laboratory data

and develop a ical expression to showthe relationship betweenpressure and volume

AC adapter for CBLunit

CBL-DIN adaptergas pressure sensorsyringe

Suppose 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

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?

2. What is the definition of pressure, volume, andtemperature?

3. Read over the entire laboratory activity Form

a hypothesis as to how volume and pressure are related in a closed system Record yourhypothesis on page 14

4. What variables are changed in this lab? What isheld constant?

Section 14.1

TI calculator

Link cable

AC adapter for CBL unit

Syringe

Gas pressure sensor DIN adapter

Procedure

Part A: Preparing the CBL System

1. Connect the syringe to the gas pressure sensor

Then connect the CBL unit to both the gas

pres-sure 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

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

2. Press the plunger of the syringe down to the 5 mLmark When the pressure gauge stops changing,press TRIGGER on the CBL unit Enter 5 as the

mL on the graphic calculator

3. From the DATA COLLECTION menu, selectMORE DATA

4. 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

5. After the last set of data, select STOP ANDGRAPH

6. Select GRAPH on your calculator to see a linegraph Press STAT and then choose EDIT Thedata are now displayed Volume will be inColumn 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 Followingyour teacher’s directions, return all equipment to itsproper place

Hypothesis

Figure A

Data and Observations

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

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

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?

1. Why would it be important for a scuba diver to

be familiar with Boyle’s law?

2. What are some common household productsthat utilize Boyle’s law?

Real-World Chemistry