Q & A
What is IMMEX?
IMMEX stands for interactive multimedia exercises, and this is an internet – based
software package designed to obtain in – depth information about student problem solving.
This software package was developed at the UCLA medical school. These problems can
be used in the classroom for free.
Why IMMEX?
IMMEX differs from traditional software packages in its ability to track student
movements. Therefore, we can readily identify what items students used to solve the
problem, the amount of time they viewed the items, and even the order in which the items
were viewed.
What types of problems are available?
IMMEX problems are case – based problems similar in style to problems used in
business and medical schools. These problems are designed to assess student abilities in
unique situations that they may encounter on a job or graduate school. With regard to
chemistry, the following list is just some of the topics for which IMMEX problems are
available:
Topic
Stoichiometry…………………………………………………..
Gas Laws……………………………………………………….
Qualitative Inorganic Analysis………………………………..
………………………………..
Qualitative Organic Analysis………………………………….
Stereochemistry………………………………………………..
Periodic Trends…………………………………………………
Enthalpy…………………………………………………………
Organic Mechanisms…………………………………………..
Organic Synthesis………………………………………………
………………………………………………
Electrochemistry………………………………………………..
Lewis Structures and Physical Properties……………………
Separation of a Mixture………………………………………..
Kinetics………………………………………………………….
Thin Layer Chromatography………………………………….
Organic Spectroscopy…………………………………………
Acid-Base Chemistry and Buffers……………………………
Analytical Spectroscopy………………………………………
IMMEX Problem
Convertible
Rust Never Sleeps
Hazmat
Desperately Seeking Solution
Finding Carbons Neighbors
In - Stereo
Periodic Trends
Coins R Us
OrganoMech
Aro-Synth
Mega-Synth
Coulomb’s Lab
Lewis Structure
Separation
Mechanism Mechanics
Chromatography Challenge
Spectra Analysis
Buffer
Analyze That!
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Can students memorize how to do the problems?
No, students must understand the underlying concepts because for each problem
there are between 5 and 60 cases, and one strategy will not suffice for all of the cases.
For example, with Hazmat students may have a flame test negative compound in one case
and a flame test positive compound in another. Therefore, successful strategies will need
to be tailored for each problem case.
Can students work together?
Yes, if that is your intentions. Students cannot work together if they login using two
different IDs because they will most likely get a different problem case, but they can work
together if they login using only one ID. Because of the relatively large number of cases
associated with these problems, unwanted collaboration is minimized.
How are the problems assessed?
Students are provided with immediate feedback stating whether their solution was
correct or incorrect. Most problems given students more than one attempt (usually two) to
arrive at the correct solution. As far as grades are concerned, most of that is up to the
individual instructor, but here are some suggestions:
1. Effort – Based Grading: Students are assigned a number of problem cases and
receive full credit if they complete the minimum number of cases.
2. Performance – Based Grading: Students are assigned a number of problem cases,
and are told that they must answer a certain number of these cases correctly in order to
receive full credit. For example, students may be assigned 5 cases, and they are told
they have to get 3 of the 5 correct.
3. Strategy – Based Grading: This is like performance based; however, the requirements
are more stringent. Students are told that they must do a given number of cases in
which they must get a minimum number correct, but they lose fractions of their points
for each problem case worked to get the minimum beyond the number of cases
assigned.
Example: Students are assigned 5 problem cases (4 of which must be answered
correctly) for a 10 point assignment.
{(Number of Correct (Max of 4)) – (Number Attempted – Number Assigned)*0.15)} x 2.5
At Clemson University, we typically use a combination of the methods above in particular
the effort – based and strategy – based systems. Students will receive 40 to 60% of the
credit by completing the minimum number of assigned problems, and the remaining credit
will be assigned based upon the correctness of their answers.
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How do I create an account for IMMEX?
Go to the IMMEX website (www.immex.ucla.edu) and click on “Sign Up to Use
IMMEX.” Follow the instructions to create a personalized account.
Where can I sign up to use IMMEX problems with my classes?
After creating a personalized account (as detailed above), go to the IMMEX website
(www.immex.ucla.edu) and click on “Schedule My Class to Use an IMMEX Problem Set.”
Follow the instructions provided to stage problems for your class. The IMMEX staff
requests that you allow one week to process the staging request.
What information will I receive after staging the problems?
You will receive basic information concerning IMMEX and a list of student IDs and
passwords. The student IDs are a 12 – characters in length consisting of both numbers
and letters, and the ID includes the year, course title, instructor name, and unique digits
assigned to each student. Students may have difficulty differentiating between numbers
and letters in some cases – so it is best to be aware of this.
How can I login to the site?
Use the login ID (your email address and password) to login to the site. The
instructor login will give you access to all of the student performances for each of the
classes in which IMMEX problems have been staged. Please note that if you have popblockers, then you may not be able to login to the site because a new window will pop-up
listing the classes (instructor) or problem sets (students) available.
How do I view student performances?
Login to the IMMEX site using your personal ID (your email address) and password.
After logging in, click on Teachers’ Aid, then classes, and then select the appropriate
course. A complete list of performances will appear as well as a graph the class’
performance index which identifies the number of problems attempt vs. the number
correct. After this screen appears, scroll down to see other menu options. You decide
whether you want to view of all the information for the class by clicking on the “Download”
option to view everything in either a tab-delimited or Microsoft – Excel file or results for
individual problems or students.
What are the components of the Tab-Delimited and Microsoft – Excel files?
Class Title | Problem Set Name | Student Login ID | Number Correct | Number Attempted | Percent Correct | Index
Can students change their password?
Yes, and it is recommended. By changing the password, this will eliminate students
mistakenly (or intentionally) working problems under other users’ names. If students lose
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their passwords, they can be obtained easily by the instructor by going to Teachers’ Aid,
classes, and then scrolling down to the bottom of the screen and downloading the class
roster. This will have a list of login IDs and their passwords.
How will incorporating IMMEX problems affect the curriculum?
Because of the nature of IMMEX problems, large scale changes in the curriculum
will not be required. Most IMMEX problems can serve as a substitute for traditional
homework assignments, quizzes, or even tests. The IMMEX problems were designed to
ensure that they can easily be tailored for implementation in the classroom.
How will students respond?
For the most part, students have responded favorably at Clemson. Students who
are less familiar with technology may have difficulty, but after working one or two
problems, such will become familiar with the software such that problems will be
minimized. Generally, students comment on the usefulness of the interactive environment
and prefer working these problems instead of traditional homework problems or quizzes.
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Elements of IMMEX Problems
IMMEX problems are designed to focus on the four elements of problem solving
namely: identification of goals and objectives, problem representation, strategy
development, and verification. These problems are equipped with an HTML tracking ability
and can readily identify each of these four elements as a basis for the development of a
greater understanding of student problem solving. The goal of these problems is to use
this resulting understanding as a way of implementing teaching methodologies to best
foster understanding of chemistry concepts.
The IMMEX problems are case – based problems similar to what is used for
medical and business schools. Each problem begins with a prolog statement designed to
describe the problem scenario. For example, the Lewis Structure problem has the
following prolog:
Your team of forensic scientists has found an unlabelled vial at the scene of a
crime. It is your job to identify the substance by performing the appropriate tests and
observations of the compound. Once you think you have identified the compound
you should choose the Lewis structure that corresponds most closely with the data
that you have collected.
After students read the prolog statement, they are equipped with the goals and
objectives of the problem (the first aspect of problem solving). Students are then prepared
to navigate throughout the rest of the problem space (all of the available information for
students to view). The problem space provides the second aspect of problem
representation and generally includes library information. In cognitive science, the
problem space is associated with all of bits of information students string together when
solving problems. With this in mind, the problem space was designed to include all
information which students may find relevant, even though, experts may find some
information as useless and irrelevant. The inclusion of such information is important
because this can be used as a basis for identifying where students go wrong, as well as,
alternative conceptions. The problem space for each chemistry IMMEX problem is
provided in this workbook. A graphical representation for the problem for Hazmat is
provided in Figure 1. The different colors represent the different types of items available
for students to view. The gray item is the prolog, and all students will view the prolog by
default. The green items are library items, the red items are physical properties, the purple
items are acid-base tests, the blue items are chemical reactions, and the yellow item is the
inventory.
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Figure 1: The problem space for Hazmat.
The strategy development is modeled using IMMEX’s HTML tracking ability. Using
this software, it is possible to determine the items viewed, the order in which they are
viewed, whether they are viewed more than once, and the amount of time in which they
are viewed. This strategy development is depicted using what is known as a search path
map. Colors are lines are used to indicate how students have transitioned throughout the
problem space. Gray items are items that students elected not to view, and items in color
were viewed. Lines are draw between items to represent how students moved around in
the problem space. A line from the left edge of an item box to the center of an item box
represent a transition in the problem space. Figure 2 provides an example of a search
path map for Hazmat. One important note is that unlike written assessments, students
cannot leave out pertinent information from the search path maps.
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Basic
Information
about the
performance
Strategy
Development
Relative
amount of
time spent
on each
type of
item.
Figure 2: Search Path Map for Hazmat
Additional information is also provided on the search path map such as whether the
problem was completed and solved correctly, the problem case, the total amount of time
spent on the problem, and the relative amount of time spent on each type of item.
There are several possible classroom activities that can be incorporated to aid in
the development of problem solving skills. These activities include:
 Metacognitive activities in which students describe why they chose a particular
path and explain how they could improve their strategy in the future. Students
can answer questions concerning why a particular strategy was either
successful or unsuccessful, and can work on developing a better strategy for
future problems. From this activity students could be required to develop a
strategy and implement it for a new case.
 Group assignments in which successful and unsuccessful students are paired to
discuss how their strategies differ.
 Classroom discussions in which students collectively describe their reasoning
when solving a problem. The discussion can include problem space items that
students felt were relevant or irrelevant, the logical progression of how to move
throughout the problem space, and how strategies would differ for different
cases.
The final aspect of problem solving, verification, is tracked as well by determining
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whether students view problem space items more than once. This will indicate whether
students are verifying their understanding and logic. In addition, the problems are
equipped with point systems that will either add or subtract points from students’ overall
scores. These point systems are in place to make students more aware of their actions. If
points are at stake, students will be less likely to view all of the problem space items –
therefore, this will force students to become more selective in their actions. Finally,
students are asked to verify their conclusion before submitting the final result. Most
problems will also allow students who are unsuccessful on the first attempt to try again.
Students are given the opportunity to review the problem space items once again, thereby,
verifying or re-evaluating their initial conclusions.
The problems will provide immediate feedback to students, thereby providing them
with reassurance if they are correct or perhaps motivating them to review concepts if they
are incorrect. From an instructional standpoint, this can be used to determine whether
concepts need to be reviewed in class or whether some other type of intervention such as
collaborative group is needed. Figure 3 provides an example of a feedback screen for
students.
Figure 3: Immediate feedback provided to students.
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IMMEX Information for Students
Basic Information:
The IMMEX software is designed to study how people solve problems. It is
equipped with an HTML tracking device that will identify how students navigate throughout
the problem space which is simply all of the available information ranging from physical or
chemical tests to a library. This software serves a tool to identify misconceptions or gaps
in understanding and can be used to identify when intervention methods should be
implemented.
Login Information:
1.
2.
3.
4.
5.
Go to www.immex.ucla.edu
Use your assigned login ID and password.
Select Clemson University as the affiliation.
Hit enter. A screen should appear stating that you are being logged into the system.
A series of problem sets will appear. Select the appropriate problem set.
Change Your Password:
Once you have logged into the system, and the series of problem sets appear, go to the
password icon and follow the directions.
Working the Problem Set:
1. All problems will begin with a prolog statement which identifies the goal of the problem.
Read this statement carefully.
2. There are several toolbars available for navigation. These toolbars are generally
located at the top and bottom of the window.
3. View as much or as little information as you deem necessary to solve the problem.
4. Once you feel that you have collected enough information, proceed to solve the
problem by clicking on the solve menu on the lower toolbar. IMPORTANT: Once you
click on the solve menu, you will be required to submit an answer – you generally will
NOT be able to go back.
5. Most IMMEX problems allow two submissions (or two attempts at the correct answer).
You know that you have completed the problem, when a screen such as the following
appears:
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Toolbars
If you are incorrect, a screen such as the following will appear. If you have not exhausted
all of your attempts, you can go back and review as much of the information as you wish
and try the problem again. Please note that once you have exhausted all of your chances,
the IMMEX software will no longer track your progress. However, you can click on
problem sets, and then click on the same problem set to begin a new case. Each IMMEX
problem has between 5 and 60 cases – therefore, you will have multiple opportunities to
work the same type of problem.
Toolbar
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Tracking Your Performance:
After logging in, go to the MAPSS icon on the problem set page. Then go to get my
performance progress report. This will provide a detailed list of all problems that have
been completed correctly or incorrectly, as well as, all of the problems that have been
started.
Additional Information:
1. Use only Internet Explorer or Netscape (the latest versions of each).
2. Do NOT use Mozilla, Firefox, Safari, or AOL browsers because there may be some
compatibility issues.
3. If you have popup blockers, then the IMMEX site may not be able to load.
4. Do not hit SOLVE until you are ready to enter a solution. Once you hit solve, you will
not be able to review data and will be required to submit an answer.
5. Most problems have a point system that is designed to track your actions. The points
accumulated or lost in the problem will NOT affect your grade. All that affects your
grade is whether you are successful at solving the minimum number correctly and
whether you attempt the minimum number assigned.
6. After completing a problem and reaching the screen with dancing icon, go to Problem
Sets on the lower toolbar, and click on the problem that you wish to work (this will bring
up a new case of the problem set that you have just solved). There is no need to logout
to get a new case. There is no need to log out and log back in to complete a new
problem.
7. Do not contact the IMMEX staff for support – contact your instructor.
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Hazmat
Problem Description
This problem focuses on qualitative inorganic analysis using chemical reactions to
identify anions, flame tests to identify cations, conductivity and solubility tests, and litmus
paper tests to identify the relative pH.
Problem Goals and Objectives


Assess student understanding of basic techniques commonly emphasized in general
chemistry including flame tests and precipitate tests.
Provide a comparison with the laboratory results from the use of the multimedia flash
videos. Students can compare their observations with those in the problem.
Number of Different Cases
Ammonium carbonate
Ammonium chloride
Ammonium nitrate
Ammonium sulfate
Barium chloride
Barium hydroxide
Barium nitrate
Calcium chloride
Calcium hydroxide
Calcium nitrate
Carbonic acid
Copper (II) chloride
Copper (II) nitrate
Copper (II) sulfate
Hydrochloric acid
Iron (III) chloride
Iron (III) nitrate
Iron (III) sulfate
Iron (III) nitrate
Led (II) nitrate
39
Magnesium chloride
Magnesium nitrate
Magnesium sulfate
Nitric acid
Potassium carbonate
Potassium chloride
Potassium hydroxide
Potassium nitrate
Potassium sulfate
Silver nitrate
Sodium carbonate
Sodium chloride
Sodium hydroxide
Sodium nitrate
Sodium sulfate
Strontium chloride
Strontium hydroxide
Strontium nitrate
Sulfuric Acid
Implementation
This problem is used in conjunction with a qualitative inorganic analysis experiment
in the first semester general chemistry laboratory. The problem is completed before
starting the experiment and after completing it.
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Information Available for Students
Physical Tests
1.
Flame Test (an illustration will be provided for the students—therefore, students
must draw their own conclusions)
2.
Conductivity Test
In this case, the solution is conductive.
3.
Solubility Test
A movie is shown which depicts solid being added to solution and stirred. A message is
provided indicating whether the solid is soluble or insoluble.
13
Chemical Tests
1.
Red Litmus
2.
Blue Litmus
This provides the same type of result as the red litmus test but uses blue litmus paper.
Reaction with:
1.
Hydrochloric Acid
14
2.
Sodium Hydroxide
3.
Silver Nitrate
15
4.
Sodium sulfate
5.
Potassium iodide
6.
Barium nitrate
For all of the reactions above, a Flash macromedia player is needed to visualize the
results. For 3 – 6, either a precipitate will be observed as with case 3 or a message
indicated that no visible reaction has taken place. For the acid – base reactions, a
message will be provided indicating whether there has been a change in temperature.
Library
1.
Glossary of Terms
acidic solutions which have pH less than 7.0
alkaline solutions which have basic pH anion a negatively charged ion basic solutions
which have pH greater than 7.0
boiling point temperature at which a liquid changes into a gas
carcinogen a substance that causes cancer in some living things
cation a positively charged ion
conductivity degree to which electricity or heat moves through a substance
density relationship between mass and volume of a substance
electrolyte substance which conducts electricity in its aqueous form
flame test method of identifying metallic ions by placing a small sample in a bunsen
burner flame
hazmat specialist a person on a specially trained team that is called upon to advise,
fight, or clean up any hazardous material or spill
litmus paper paper strips soaked in litmus solution, used to determine acidity or
alkalinity of a solution mass quantity of matter in a substance
melting point temperature at which a solid changes into a liquid
nvr no visible reaction
pH inverse log of the hydrogen ion concentration, indicates the degree of acidity or
alkalinity of a solution
solubility degree to which a substance dissolves in a specific solvent volume space
occupied by a quantity of matter
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2.
Chemical Properties
the entries acidity/alkalinity, electrical conductivity, and reaction
with acid/base refer to the listed item when in aqueous solution
alkaline earth metal salts
acidity/alkalinity
solubility in water
electrical conductivity
reaction with acids
reaction with bases
cation
tend to form neutral solutions
high to low depending on anion
soluble forms have high conductivity
generally form neutral solutions
no visible reaction
alkali metal salts
acidity/alkalinity
solubility in water
electrical conductivity
reaction with acids
reaction with bases
cation
tend to form neutral solutions
high
high
no visible reaction
no visible reaction
ammonium salts
cation
acidity/alkalinity
solubility in water
electrical conductivity
reaction with acids
reaction with bases
depends on properties of anion
high
high
depends on properties of anion
pungent gas released
acidity/alkalinity
solubility in water
electrical conductivity
reaction with acids
reaction with bases
tend to form alkaline solutions
many are insoluble
soluble forms have high conductivity
generates carbon dioxide gas
no visible reaction
carbonates
anion
halide salts
anion
acidity/alkalinity tend to form neutral solutions
solubility in water high solubility except those with lead,
mercury, and silver ions
electrical conductivity soluble forms have high conductivity
reaction with acids no visible reaction
reaction with bases no visible reaction
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hydroxides
anion
acidity/alkalinity
solubility in water
electrical conductivity
reaction with acids
reaction with bases
tend to form alkaline solutions
depends on cation
soluble forms have high conductivity
water formation, heat generation
no visible reaction (hydroxides are bases)
acidity/alkalinity
solubility in water
electrical conductivity
reaction with acids
reaction with bases
form alkaline solutions where soluble
insoluble
insoluble forms have no conductivity
heat generated
no visible reaction
oxides
anion
nitrate salts
anion
acidity/alkalinity
solubility in water
electrical conductivity
reaction with acids
reaction with bases
form neutral solutions
high
high
no visible reaction
no visible reaction
sulfite salts
anion
acidity/alkalinity
solubility in water
electrical conductivity
reaction with acids
reaction with bases
3.
generally form acidic solutions
depends on cation
soluble forms have high conductivity
forms toxic, pungent gas
depends on cation
Solubility Rules
1. all alkali metal salts are soluble
2. all ammonium salts are soluble
3. all nitrate salts are soluble
4. all acetate salts are soluble, except those of the silver and mercury II ions
5. all halide salts are soluble, except those of the silver, lead II, mercury I ions
6. all sulfate salts are soluble, except those of the calcium, strontium, barium, lead
II, and mercury I ions
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7. most sulfide salts are insoluble, except those of the alkali metals, ammonium,
barium, strontium, and calcium ions
8. most hydroxides are insoluble, except those of the alkali metals, ammonium,
barium, strontium, and calcium ions
9. all carbonate, phosphate, and sulfite salts are insoluble, except those of the
alkali metals and ammonium ions
4.
Flame Key
5.
Litmus Key
red litmus paper stays red in unknown solution – solution is not basic
19
red litmus paper turns blue in unknown solution – solution is basic
blue litmus paper stays blue in unknown solution – solution is not acidic
blue litmus paper turns red in unknown solution – solution is acidic
20
5.
Conductivity Key
zero conductivity, non-electrolytic solution
partial conductivity, semi-electrolytic solution
High conductivity, electrolytic solution
21
6.
Periodic Table
This periodic table is interactive and students can click on elements to view the following
information:
 Atomic Number
 Atomic Mass
 Boiling Point
 Melting Point
 Oxidation States
Chemical Inventory
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Solving the Problem
When students feel they have collected enough information to the solve problem, they can
click on solve, and they will be given a pull down menu with 39 possible choices. This
problem allows 2 attempts.
Average Time Needed to Complete a Case 10 – 20 minutes
Average Solve Rate
Approximately 50%
Associated Assignments
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At Clemson, a qualitative inorganic analysis experiment is completed in conjunction with
this IMMEX problem. This project is available in Cooper’s Cooperative Chemistry
laboratory manual.
Convertible
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Problem Description
An important problem solving skill for general chemistry and even advanced
chemistry courses is the ability to do stoichiometry problems. This problem is designed to
aid students with stoichiometry by providing them with a tutorial that identifies their errors.
Problem Goals and Objectives



Identify where students go wrong in completing stoichiometry problems.
Allow students to conceptualize their errors in preparation for quizzes and exams.
Prepare students for more challenging stoichiometry problems.
Number of Different Cases
9 (each case has multiple other cases with different
numbers)
Case 1
To determine the mass of carbon dioxide produced when a given mass of gasoline (C 8H18)
is burned in air.
Case 2
How many grams of water are produced when Xg of gasoline (C8H18) are used in the
combustion as shown below? 2C8H18 + 25O2  16CO2 + 18H2O
Case 3
How many grams of CO2 are produced when Xg of O2 are used in the combustion as
shown below? 2C8H18 + 25O2  16CO2 + 18H2O
Case 4
How many grams of H2O are produced when Xg of O2 are used in the combustion as
shown? 2C8H18 + 25O2  16CO2 + 18H2O
Case 5
How many grams of C8H18 are produced when Xg of CO2 are used in the combustion as
shown? 2C8H18 + 25O2  16CO2 + 18H2O
Case 6
25
How many grams of O2 are produced when Xg of H2O are used in the combustion as
shown? 2C8H18 + 25O2  16CO2 + 18H2O
Case 7
How many grams of C8H18 are produced when Xg of H2O are used in the combustion as
shown? 2C8H18 + 25O2  16CO2 + 18H2O
Case 8
How many grams of O2 are produced when Xg of CO2 are used in the combustion as
shown? 2C8H18 + 25O2  16CO2 + 18H2O
Case 9
How many grams of CO2 are produced when Xg of C8H18 are used in the combustion as
shown? 2C8H18 + 25O2 -> 16CO2 + 18H2O
Solving the Problem
Students can opt whether they want to complete the tutorial or immediately solve the
problem after reading the question. For students who are very well skilled in solving
stoichiometry type problems this will be merely an exercise. The icons below illustrate the
types of information that students can elect to view:
The tutorial begins with the following message:
Choose your starting point:
g C8H18
g O2
g CO2
g H2O
1 mol C8H18
1 mol O2
1 mol CO2
1 mol H2O
The remainder of the problem involves choosing the appropriate conversion factor from the
following list:
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The completed problem will have the following form:
X
X
X
The problem then instructs students to click on solve and select a numerical answer from a
list of possibilities.
Implementation
This problem is used in the first semester general chemistry course following a unit
on mole conversions and stoichiometry. Students are asked to complete each case of
problems in preparation for the exam.
Coins R Us
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Problem Description
This problem deals with thermochemistry and concepts pertaining to heat, specific
heat, and changes in temperature. The prolog statement is as follows:
Your interview with Coins R’ US has gone very well. Everyone seems impressed. You are
told the final decision will be based on your performance of “a little test” and lead to a small
room containing a few familiar items. You are given a handful of identical coins and asked
to determine what metal they are made from. You are wished “Good luck.” as the door is
closed. This was not the test you had in mind, and after a moment of panic you proceed.
Problem Goals and Objectives


Identify information students use when working problems related to heat. Specifically
what information do students view that is relevant and irrelevant as a basis for
identifying alternate conceptions.
Determine whether errors are likely resulting from conceptual errors or mathematical
errors. This can be determined by assessing the information viewed and determining
whether students could have gotten the answer correct based on this information.
Number of Different Cases
Aluminum
Copper
Lead
Magnesium
Manganese
Nickel
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Silver
Tin
Tungsten
Titanium
Uranium
The problem then instructs students to click on solve and select a numerical answer from a
list of possibilities.
Implementation
This problem is often used in the laboratory following an experiment entitled Hot
and Cold in which students determine the heat evolved in a set of reactions using the
formula: q = mcT. By the time students work through this problem, related concepts had
been covered in lecture.
Information Available for Students
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Coins
1.
Denomination
There is no value indicated on the coin.
2.
Density determination
There is insufficient equipment to determine density.
3.
Final temperature
4.
Initial temperature
You placed the coins in a preheated temperature controlled drying oven, set at 80.2
C. After temperature equilibrium, you remove the coins from the oven and
immediately place them into the calorimeter.
5.
Inscription
On the reverse of the coin are the words, “Reading this will not help you”.
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6.
Mass
This is mass of all the coins together.
7.
Shape
Each coin is circular.
Inventory
1.
Balance
The analytical balance accurately displays to 000.01g. The balance was used to
determine the:
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

2.
Total mass of the coins.
The mass of the water used in the calorimeter.
Calorimeter
The calorimeter is a device that is used to measure thermal properties. It can be
used indirectly to determine the specific heat of the coins by noting the change in
water temperature after the addition of the heated coins. Assume no loss of heat
from the calorimeter.
3.
Coins
The coins has been specially minted by the Coins R’US Company. These coins are
made of the same pure metal. Your task is to determine which pure metal was
used.
4.
Thermometer
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The thermometer is accurate to 0.1 oC. It was used to determine the:
1. Initial temperature of the water and calorimeter.
2. Final temperature of the water, calorimeter, and coins.
5.
Drying Oven
The drying oven maintains a preset temperature. The coins are placed into the
oven, heated to the preset temperature, removed, then immediately placed into the
calorimeter.
7.
Water
32
The pure water is used in the calorimeter and has a specific heat of 4.184 J g-1oC-1. You
will need to know the mass of water and the initial and final temperatures in order to
calculate the total heat gained by the calorimeter.
Water
1.
Final Temperature
33
2.
Initial temperature
The initial temperature of the equilibrated water and calorimeter is 22.8 C.
3.
Mass
Mass of the water in the calorimeter:
Reference
1.
Formulas
q =c m ∆T
qgain = - qloss
where q is the energy gained or lost, c is the specific heat of the object gaining or
losing heat, and ∆T is its change in temperature. Assume no heat loss from
calorimeter.
34
2.
Density Table
Al
Cr
Co
Cu
Au
Fe
Pb
Mg
Mn
Ni
Pt
Ag
Sn
Ti
W
U
Zn
H2O
3.
Metal
Aluminum
Chromium
Cobalt
Copper
Gold
Iron
Lead
Magnesium
Manganese
Nickel
Platinum
Silver
Tin
Titanium
Tungsten
Uranium
Zinc
Water
Density( g/cm3 )
2.699
7.19
8.9
8.96
19.32
7.87
11.35
1.738
7.44
8.88
21.45
10.5
7.31
4.54
19.3
18.95
7.13
1.00
m.p. (C)
660
1860
1492
1083
1063
1535
327
651
1244
1453
1769
960
232
1675
3380
1132
420
0.0
Specific Heat Table
Al
Cr
Co
Cu
Au
Fe
Pb
Mg
Mn
Ni
Pt
Ag
Sn
Ti
W
U
Zn
H2O
Metal
Aluminum
Chromium
Cobalt
Copper
Gold
Iron
Lead
Magnesium
Manganese
Nickel
Platinum
Silver
Tin
Titanium
Tungsten
Uranium
Zinc
Water
Specific Heat J/(gC)
0.903
0.461
0.440
0.385
0.132
0.449
0.129
1.025
0.448
0.461
0.134
0.235
0.213
0.528
0.138
0.112
0.444
4.184
35
Buffer
Problem Description
This problem requires students to use acid-base chemistry (Henderson-Hasslebalch
equation) to determine the appropriate buffer system and concentration of each
component.
Problem Objectives


Provide students with a real-world scenario in which acid-base chemistry and buffers
are important.
Require students to synthesize information on acid-base chemistry to determine the
correct buffering system.
Number of Cases
12
Tank pH
Pref. Fish pH
Buffer
Molarities
Grams (5 gal. tank)
6.5
7
Phosphate
0.0250 M salt
0.0405 M acid
82.1 g K2HPO4
104 g KH2PO4
6
8.5
Ammonia
0.0100 M salt
0.0575 M acid
3.21 g NH3
58.0 g NH4Cl
6.5
5.5
Acetate
0.0562 M salt
0.0100 M acid
87.0 g NaC2H3O2
11.3 g CH3COOH
4
6
Bis-Tris HCl 0.0100 M salt
0.0316 M acid
39.4 g Bis-Tris
147 g Bis-Tris HCl
5
6.5
Bis-Tris HCl 0.0100 M salt
0.0100 M acid
39.4 g Bis-Tris
46.4 g Bis-Tris HCl
7
8
Phosphate
202 g K2HPO4
25.7 g KH2PO4
8
6.5
Bis-Tris HCl 0.0100 M salt
0.0100 M acid
39.4 g Bis-Tris
46.4 g Bis-Tris HCl
5.5
7.5
Phosphate
0.0195 M salt
0.0100 M acid
64.0 g K2HPO4
25.7 g KH2PO4
9
7.5
Phosphate
0.0195 M salt
0.0100 M acid
64.0 g K2HPO4
25.7 g KH2PO4
0.0616 M salt
0.0100 M acid
36
Tank pH
Pref. Fish pH
Buffer
Molarities
Grams (5 gal. tank)
6
7.5
Phosphate
0.0195 M salt
0.0100 M acid
64.0 g K2HPO4
25.7 g KH2PO4
8
4.75
Acetate
0.0100 M salt
0.0100 M acid
15.5 g NaC2H3O2
11.3 g CH3COOH
8.5
7
Phosphate
0.0250 M salt
0.0405 M acid
82.1 g K2HPO4
104 g KH2PO4
Information Available to Students
The problem begins with a prolog statement such as:
Your Lake Malawi Cichlids keep dying in your 5 gallon fish tank. The Cichlids generate alot
of waste and you notice some decomposed fish food in the tank. You suspect an
unhealthy water pH. In the past you have adjusted the pH using acid and base. You decide
if pH is again the problem you will try to "buffer" the system against future pH changes
caused by the fish waste and decomposed fish food.
After reading the prolog statement, students are ask:
What will be done first?
1. Select a buffering system.
2. Determine the tank's pH.
3. Determine buffer molarities needed.
The answer is of course to determine the tank pH, and students will be prompted to select
another option if they do not select this one at first.
Options for Determining Tank pH
1.
Test with litmus paper
2.
Test with universal pH paper
3.
Test with universal liquid indicator
4.
Test with phenolphthalein
37
These tests are depicted using macromedia flash software. The result of the test with
universal pH paper is shown below.
After viewing the pH results, students are asked to identify the pH of the tank from a list of
possible choices such as: 4.0, 4.5, 5.0, 5.5, etc. After identifying the correct pH, they are
then asked if that is the correct pH for their fish. The problem is designed such that the pH
does not match so that students will have to develop a buffering system. Students will
then be prompted to select the appropriate buffer from a list of options.
BUFFER SYSTEMS
1. Acetic Acid/Sodium Acetate
2. Carbonic Acid/Sodium Bicarbonate
3. Ammonia Chloride/Ammonia
4. Potassium Dihydrogen Phosphate/Potassium Hydrogen Phosphate
5. Bis-Tris.HCl/Bis-Tris
After selecting the appropriate buffer system, students are then asked to select the
appropriate molarities for the salt and acid.
1. 0.0562M salt with 0.0100M acid
2. 0.0100M salt with 0.0316M acid
3. 0.0250M salt with 0.0405M acid
4. 0.0100M salt with 0.0100M acid
5. 0.0195M salt with 0.0100M acid
6. 0.0616M salt with 0.0100M acid
7. 0.0100M salt with 0.0575M acid
38
After this step, students are prompted to solve the problem by selecting the appropriate
gram quantities for the salt and acid from a pull down menu list.
Library Information
pH Test
1.
Key for litmus test
pH<7
2.
pH>7
pH=7
Key to pH indicator paper
pH=4
pH=5
pH=6
pH=7
pH=8
pH=9
39
3.
4.
Key to pH indicator solution test
pH=4
pH=5
pH=5.5
pH=6
pH=6.5
pH=7
pH=7.5
pH=8
pH=8.5
pH=9
Phenolphthalein Test
A color test to indicate pH:
The indicator changes in the range of pH 8.2 - 10.0
If the solution is
colorless, the pH is
below this range.
If the solution is pink,
the pH is above this
range.
pKa values
1. Acetic Acid pKa=4.75
2. Ammonia pKa=9.26
3. Benzoic Acid pKa=4.20
4. Carbonic Acid pKa1=6.20 pKa2=10.3
5. EDTA pKa1=10.7 pKa2=7.56
40
6. Glutamic Acid pKa1=3.85 pKa2=7.84
7. Glycine pKa1=2.3 pKa2=9.60
8. Maleic Acid pKa1=1.83 pKa2=6.07
9. Phosphoric Acid pKa1=2.12 pKa2=7.21 pKa3=12.3
10. "Tris" = Tris (hydroxymethyl) aminomethane pKa=8.10
11. "Bis-Tris" = 2,2-Bis(hydroxymethyl)-2,2',2"-nitrilotriethanol pKa=6.50
Acid and Base Ionization Equations
Acetic Acid
CH3COO- + H3O+ pKa = 4.75
CH3COOH + H2O
Ammonia
NH4+ + H2O
NH3 + H3O+ pKa = 9.26
Carbonic Acid_
H2CO3 + H2O
(HCO3)-+ H3O+ pKa1 = 6.20
(HCO3)- + H2O
(CO3)-2 + H3O+ pKa2 = 10.3
Phosphoric Acid
H3PO4 + H2O
(H2PO4)- + H3O+ pKa = 2.12
(H2PO4)- + H2O
(HPO4)-2 + H3O+ pKa = 7.21
(HPO4)-2 + H2O
(PO4)-3 + H3O+ pKa = 12.3
Tris
Tris.HCl + H2O
Tris + H3O+ + Cl- pKa = 8.10
Bis-Tris
Bis-Tris.HCl
Bis-Tris + H3O+ + Cl- pKa = 6.50
41
FISH pH PREFERENCES
lake malawi cichlids pH8.5
african cichlids pH8.0
guppies pH7.5
jack dempsey pH7.5
tetras pH7.0
south american cichlids pH6.5
angelfish pH6.0
south american characins pH5.5
Metric/English Conversion Factors
42
1.00 liter = 1.06 quarts
454 grams = 1.00 pounds
2.54 centimeters = 1.00 inch
Molar masses
KH2PO4 136 grams/mole
K2HPO4 174 grams/mol
NaCH3COO 82.0 grams/mole
CH3COOH 60.0 grams/mole
NH4Cl 53.5 grams/mole
NH3 17.0 grams/mole
Na2HPO4 142 grams/mole
NaH2PO4 120 grams/mole
Tris.HCl 158 grams/mole
Tris 121 grams/mole
Bis-Tris.HCl 246 grams/mole
Bis-Tris 209 grams/mole
Henderson-Hasselbalch Equation
pH = pKa + log([salt]/[acid])
pH is the desired pH for the system (dependent on fish species - see library)
pKa is a constant dependent on the buffering system used (see library)
[salt] is the concentration (in molarity) of the unprotonated species *
[acid] is the concentration ( in molarity) of the protonated species *
*refer to library for ionization equations showing protonated/unprotonated species for each
buffer.
Mechanism Mechanics
43
Problem Description
This problem requires students to interpret kinetic data to determine the appropriate
mechanism for a chemical reaction.
Problem Objectives


Assess students’ understanding of kinetic data and their ability to apply this information
in a laboratory – type setting.
Provide students’ with a real-world type example of why kinetic data is important in
chemistry.
Number of Cases
5
Information Available to Students
Experimental Data
DATA TABLE: Initial Concentrations
Experiment
Number
1
2
3
4
5
Initial
Initial
(CH3I) (M) (OH-) (M)
0.22
0.44
0.22
0.44
0.69
0.22
0.44
0.44
0.22
0.23
Initial Rate of
Reaction (M / s)
-
By clicking on the experiment number, students are given the initial rate of reaction.
In example,
Experiment
Number
1
2
3
4
5
Initial
Initial
(CH3I) (M) (OH-) (M)
0.22
0.44
0.22
0.44
0.69
0.22
0.44
0.44
0.22
0.23
Initial Rate of
Reaction (M / s)
-
1.26 x 10-5
-
Rate Equation
44
Potential Rate Equations for
CH3I (aq) + OH- (aq) )
CH3OH(aq) + I- (aq)
Which corresponds to the Experimental Data?
Mechanism Determination
After students select the rate equation which they feel most accurately corresponds to the
kinetics data, then they are promoted to determine the most appropriate mechanism based
upon this data. Students will select a mechanism from this list as their answer to the
problem.
After you have determined which of the reaction mechanisms (to the right) is the
reasonable choice based on all data examined, click on the solve button below.
CH3I
CH3+ + -I (slow)
CH3I + -OH
CH3OH (fast)
45
CH3I + -OH
CH3OH + -I
CH3I + CH3I
CH3CH3 + I2 (fast)
CH3CH3 + 2-OH
-OH
+ -OH
2CH3OH (slow)
H2O + O2- (slow)
O2-+ 2CH3I + H2O
2CH3OH (fast)
Reference Materials
1.
Glossary
Reaction Rate

The increase in molar concentration of product of a reaction per unit
time or the decrease in molar concentration of reactant per unit time.
Rate Law

An equation that relates the rate of a reaction to the concentrations
of reactants raised to various powers.
Rate Constant

A proportionality constant in the relationship between rate and
concentrations.
Reaction Order

The exponent of the concentration of a given reactant species in the
rate law, as determined experimentally.
46
Elementary Reaction

A single molecular event, such as a collision of molecules, resulting
in a reaction.
Reaction Mechanism

The set of elementary reactions whose overall effect is given by the
net chemical equation.
Reaction Intermediate

A species produced during a reaction that does not appear in the net
equation because it reacts in a subsequent step in the mechanism.
Molecularity


The number of molecules on the reactant side of an elementary reaction.
1 molecule: unimolecular; 2 molecules: bimolecular; 3 molecules: termolecular
Rate-Determining Step

The slowest step in a reaction mechanism.
Equations
Rate Law Equation

rate=k [A]x[B]y . . .
Reaction Order-Determination Equation

rate2/rate1=([A]2/[A]1)x([B]2/[B]1)y...
Zeroth Order Concentration vs. Time Equation

[A]=[A]0 - kt
1st Order Concentration vs. Time Equation*

ln[A]/[A]o= -kt
*Also known as the Integrated Rate Law
47
2nd Order Concentration vs. Time Equation

1/[A]=1/[A]o + kt
Arrhenius Equation

ln (k2/k1)=(Ea/R)([1/T1]-[1/T2])
1st Order Half-Life Equation

t1/2=0.693/k
Periodic Table
48
Lewis Structure
Problem Description
Understanding Lewis structures is a key component in general chemistry and
organic chemistry, particularly with regard to bonding and reactivity. This problem requires
students to develop a Lewis structure model based upon the physical properties of an
unknown compound.
Problem Goals and Objectives


Determine physical properties students deem as relevant or irrelevant.
How well do students make the connection between physical properties and structure?
Do students understand that properties are a consequence of structure?
Number of Different Cases
10
Ethanol
Dimethyl ether
Dioxane
Diethyl ether
Ethyl acetate
Piperdine
Butanoic Acid
Butanol
Butane
Pentylamine
Implementation
At Clemson, this problem is used in both the second semester general chemistry
lecture and at the beginning of organic chemistry. The problem is assigned after the
general chemistry unit on organic chemistry where functional groups are introduced. In
organic chemistry, this problem is used to introduce or review organic functional groups
and the physical properties commonly associated with these groups.
What Information is Provided for Students
a.
Analysis
1.
Elemental Analysis – This identifies the percentage of carbon
and hydrogen in the unknown. Nitrogen and oxygen data is not provided.
49
2.
b.
Mass Spectrometry – This data can be used to identify the molecular
weight of the unknown.
Properties
1.
2.
3.
4.
5.
6.
7.
8.
Physical State – (i.e. solid, liquid, gas)
Color
Melting Point
Boiling Point
Solubility in water
Solubility in hexane
Solubility in dilute sodium hydroxide
Solubility in dilute hydrochloric acid
It should be noted that students could look up the melting point and boiling point
information for the unknowns, however, in such cases, this can be readily identified
using the assessment information provided by IMMEX.
c.
Lewis Structures
The Lewis structures for the possible solutions are provided. These structures
are equipped with a chime plugin which will allow students to view and rotate the
structure in 3-D. The Lewis structure for ethanol is shown below.
d.
Library
1.
Melting Point
The melting point of a compound can tell you quite a bit about its structure.
The melting point is the temperature at which the “units” (typically molecules
or ions) in the compound separate and begin to flow around each other (giving what we call the liquid state). The more energy needed to separate the
units, the higher the melting point.
For example:
Ionic compounds tend to have very high melting points because in order to
melt the compound you have to supply enough energy to actually break ionic
bonds. Typically this occurs at very high temperatures, since ionic bonds are
strong.
50
Melting points for ionic compounds range from ~500 - 3000 °C
Molecular compounds tend to have lower melting points than ionic
compounds; ranging from very low (below room temperature) to ~300°C
(after this temperature compounds often start to decompose). This is
because when a molecular compounds are melted it is the intermolecular
forces (such as London forces, dipole-dipole forces or Hydrogen bonds) that
are broken, NOT the bonds that connect the atoms within the molecule itself.
Since intermolecular forces are usually weaker than covalent bonds or ionic
bonds, then the energy required to break them is smaller and so the melting
temperature is lower.
Typically for molecular compounds the melting point increases


as the molecular weight increases, (due to increases London forces),
and as the strength of the intermolecular forces increases
So for two compounds with the same molecular weight, the most polar
compound will have the highest melting point.
There are also other factors that also affect the melting point such as how the
“units” of the compound pack together.
2.
Boiling Point
The boiling point of a compound can tell you quite a bit about its structure.
The boiling point is the temperature at which the “units” (typically molecules
or ions) in the compound completely separate and go off into the gas phase
(- giving what we call the vapor or gaseous state). The more energy needed
to separate the units, the higher the boiling point.
Boiling points for ionic compounds are not usually recorded since they are so
high.
Molecular compounds tend to have lower boiling points than ionic
compounds; ranging from very low (below room temperature) to ~300°C
(after this temperature compounds often start to decompose). This is
because when a molecular compounds are vaporized it is the intermolecular
forces (such as London forces, dipole-dipole forces or Hydrogen bonds) that
are broken, NOT the bonds that connect the atoms within the molecule itself.
Since intermolecular forces are usually weaker than covalent or ionic bonds,
then the energy required to break them is smaller and so the boiling
temperature is lower.
Typically for molecular compounds the boiling point increases
51


as the molecular weight increases, (due to increases London forces),
and as the strength of the intermolecular forces increases
So for two compounds with the same molecular weight, the most polar
compound will have the highest boiling point.
3.
Solubility
The solubility of a compound can tell you a great deal about that compound's
molecular structure. The general rule of thumb is "like dissolves like" so that
polar or ionic compounds tend to be soluble in water, and non polar
compounds tend to be soluble in non polar solvents like hydrocarbons.
If a compound has polar and non-polar parts the solubility will depend on the
relative amounts of each portion of the molecule.
For example low molecular weight alcohols with up to 3 carbons e.g.
CH3CH2CH2OH are completely soluble in water in all proportions, because
the polar nature of the OH group allows Hydrogen bonding to occur with
water - which is a favorable interaction. These compounds are also
completely soluble in non-polar solvents also. However as more CH2 groups
are added (eg , CH3CH2CH2CH2OH) the solubility of the alcohol in water
decreases rapidly.
4.
Elemental Analysis
Most simple compounds - particularly those containing carbon and hydrogen
- can be subjected to combustion analysis in which the compound is burned
in air to produce carbon dioxide and water.
CxHyO + z O2
x CO2 + y/2 H2O
From the mass of the initial unknown and the masses of carbon dioxide and
water produced, the % C, %H (and by difference the %O) can be calculated.
Typically results of combustion analysis are reported in this way.
From this % composition data, the empirical formula (the lowest mole ratio of
the elements in the compound) can be calculated.
5.
Mass Spectrometry
Mass spectrometry is a technique that allows us to find the molecular weight
of a compound. The compound is vaporized and injected into a chamber
52
where it loses an electron (either by being hit with other high energy
electrons, or high energy radiation). The resulting ion may break up into
smaller fragments or stay intact, but each fragment is then accelerated by an
electric field which passes through a strong magnet towards a detector. The
ions are deflected on the basis of their charge to mass ratio – Lighter ions
are deflected more than heavier ones. The detector is calibrated in mass
units so that the heaviest ion that the detector reads is usually the ionized
molecule itself and this peak is known as the molecular ion. The lighter
fragments usually appear as smaller peaks at lower molecular weight.
6.
Lewis Structure
Lewis structures are the two dimensional representations of molecular
structures. From the Lewis structure you can deduce the shape of the
molecule and the polarity of the molecule. This will allow you to predict some
properties for the molecule.
Number of Attempts Allotted
1
Unlike most IMMEX problems, students are only given one attempt for this problem.
Please make sure your students are aware of this.
Average Solve Rate
51%
Average Time of Completion
10 minutes
53
Follow Up Assignment
Complete the assignment in groups of 3 or 4.
1.
2.
Draw Lewis Structures for each of the following:
a.
Pentane
b.
Pentanoic Acid
c.
Ethyl Propionate
d.
2-aminopentane
e.
Ethyl propyl ether
f.
Pentanol
Describe the trends in melting point and boiling point for a - f.
What Lewis structure features lead to higher melting and boiling points?
3.
Describe the trends in solubility for a – f.
What Lewis structure features lead to greater solubility in water, base, and acid?
54
Separation
Problem Description
Separating a mixture of compounds (inorganic and organic) is an important
laboratory component particularly for synthetic projects. The purpose of this problem is to
provide students with a tutorial in separating a mixture of inorganic and organic
compounds.
Problem Goals and Objectives



Allow students to observe the steps required in a separation scheme in preparation or
in conjunction with laboratory exercises.
Identify alternative conceptions held by students as to the appropriate methods for
separating a mixture.
Make a connection to lecture where related concepts such as solubility, acids and
bases, and ionic vs. covalent bonding are discussed.
Number of Different Cases
2
Mixture 1: calcium chloride, m-nitrobenzoic acid, and p – dichlorobenzene
Mixture 2: sodium chloride, benzoic acid, naphthalene
Implementation
This problem is used in both organic and general chemistry laboratories at
Clemson. The second semester general chemistry lab requires a separation of a mixture
of inorganic and organic compounds using relatively simple methods as outlined in the
problem. This problem serves as an introduction to the separation methodology. In
organic chemistry, extraction schemes are emphasized, and this problem serves to review
or even introduce in some cases separation methods. The problem is assigned before the
proposal for the separation of matter experiment is started (available in M.M. Cooper,
Cooperative Chemistry) or before extractions are needed in organic laboratory.
Information Available for the Students:
Mixture Information -- for each component in the mixture the following information is
provided.
a.
Formula
b.
Lewis Structure
c.
3D Structure (uses a Chime plugin)
d.
Physical State
e.
Color
f.
Melting Point
g.
Boiling Point
h.
Vapor Pressure
55
Separation Options
a.
b.
c.
d.
e.
f.
g.
Evaporation
Add Acid
Add Base
Distillation
Filtration
Pipette
Add Water
Reference Information
a.
Intermolecular Forces
1. London Forces
The weak attractive forces between molecules resulting from the small, instantaneous
dipoles that occur because of the varying position of the electrons during their motion
about the nuclei.
2. Hydrogen Bonding
A weak to moderate attractive force that exists between a hydrogen atom covalently
bonded to a very electronegative atom and a lone pair of electrons on another small,
electronegative atom.
56
3. Dipole – Dipole Forces
An attractive intermolecular force resulting from the tendancy of polar molecules to align
themselves such that the positive end of one molecule is near the negative end of another.
b.
Solubility Rules
1. “Like dissolves Like”-for example, if a substance is polar, it will dissolve only in
other polar substances.
2. Highly charged ionic compounds tend to be insoluble.
57
c.
Electronegativity Chart
d.
Changing Solubilities
e.
1.
Add Acid -- if a solid exhibits basic properties, treating the solid with an acid
will cause it to dissolve in the acidic solution.
2.
Add Base – if a solid exhibits acid properties, treating the solid with a base
will cause it to dissolve in the basic solution.
Laboratory Techniques
1. Distillation
Distillation is the process of heating a liquid until it boils, capturing and cooling the resultant
hot vapors, and collecting the condensed vapors. Distillation is used to purify a compound
by separating it from a non-volatile or less-volatile material. When different compounds in a
mixture have different boiling points, they separate into individual components when the
mixture is carefully distilled.
2. Filtration
Filtration is an operation for separating a liquid from a solid. There are two types of
filtrations: gravity filtration and vacuum filtration.
3. Evaporation
A solution of nonvolatile solid in a volatile solvent can be separated into its compounds by
removing the liquid solvent by evaporation. The solution is poured into an evaporating dish
which has a shape that provides a large surface area for both heating and evaporation.
When the solution becomes sufficiently concentrated, the solid will begin to crystallize.
4. Add Water
By adding water, certain components can dissolve and separate from the other
components.
5. Pipette
A laboratory technique in which a pipette is used to add or remove liquids.
58
How Students Work the Problem
To begin separating the mixture, students should click on separation scheme, and
they will receive the list of possible laboratory techniques. To start, they select a lab
technique such as add water, and a message will appear stating whether the choice is
correct or incorrect. If they are incorrect, they must select another option. If they correct,
the separation scheme is begin to develop. The process will continue until the student
reaches the end. This problem is unlike other IMMEX problems in the solution and format.
To receive credit for solving the problem, students should still click SOLVE and click
Finish.
Separation Scheme
Separation completed successfully
Average Solve Time
10 – 15 minutes
59
Associated Assignments
General Chemistry
Complete one case of the separations problem on the IMMEX server as a group (work in
groups of 2 or 3). Only one person needs to login to the IMMEX server to complete this
problem. After completing the problem, write a detailed summary explaining your thought
process as you were working through the separation scheme. Why did you choose
specific reagents? Describe in chemical terminology. What errors did you make and why?
What have you learned by completing this assignment? The summary should be written in
lab, and should be no more than 250 words.
It is also possible to give this assignment to individual students.
60
Organic Chemistry
In organic, an additional separation scheme is assigned with acidic or basic organic
functional groups, and often this scheme requires using distillation to separate a mixture of
neutral organic liquids.
Example:
Cl
OH
O
NH2
b
a
I
d
c
NaOH, ether
Organic Salt
HCl, ether
Question #1
What is the isolated
product here?
Mixture of Organics
HCl, ether
Organic Salt
NaOH, ether
Question #2
What is the isolated
product here?
Remaining
Organic Products
Question #3
What technique is
required to separate
these compounds?
a. acid - base extraction
b. distillation
c. melting point
d. TLC
61
Chromatography Challenge
Problem Description
The content of this problem focuses on the identification of an unknown using Thin
Layer Chromatography (TLC)
Problem Goals and Objectives



Identify what solvents students use for these experiments in order to identify possible
alternative conceptions about what is appropriate and inappropriate eluents?
Obtain information to identify how students piece together information concerning
functionality based upon TLC results.
Make a connection between lecture where polarity is emphasized. Can students
identify the relationship between polarity and TLC results?
Number of Different Cases
5
Acetanilide
Benzoic Acid
Benzophenone
Oxidole
Triphenylmethane
Implementation
The problem is best implemented toward the end of a first semester organic
laboratory. Students should have used TLC throughout the semester to determine the
purity of their products as well as verify their products’ identity.
At Clemson, we used this problem during the first semester sequence of organic
laboratory in which students run between one and three TLC analyses every laboratory
period. We required students to complete all 5 cases with a minimum of 4 correct.
What Information is Provided for Students

TLC Results (an actual TLC plate is provided with appropriate markings) in the
following solvents: ethyl acetate, toluene, ethanol, 1:9 ethyl acetate:toluene, 1:19
ethyl acetate:toluene.
62

Stationary phase. Students are informed of the stationary phase that is used for the
problem. It is silica in every case.

Dissolving Solvent
This is acetone in every case, but many students will likely be want to know this
information.

Other Information Concerning TLC Analyses
1. Volume of Eluent
2. Temperature
3. Visualization Method (an actual TLC plate under UV Light is provided)

Inventory of possible answer. Structures are provided, as well as, authentic R f
values for comparison with the data.

Library of Information
1. What is TLC?
2. Why use TLC?
3. Retention Index
4. Example of a TLC for Salicylic Acid
Average Solve Time
10 - 15 Minutes
Average Correct
81%
Percent of Information Used
34%
Library Information
Why Use TLC ?
TLC is a chromatographic method that is often used to obtain qualitative information about
an organic compound. In particular, this method is quite useful in identifying unknown
compounds by comparing with control compounds, as well as, determining product purity.
How does TLC work?
TLC is based on equilibration between a mobile and stationary phase. The stationary
phase for TLC is a polar material (usually silica) and the mobile phase (or eluent) has a
range of different possible polarities. Solid organic compounds are dissolved in a volatile
solvent such as acetone and are spotted on the TLC plate. The plate is then placed in a
solvent chamber where the solvent rises up the TLC plate by way of capillary action.
There is an interaction between the organic species and the stationary and mobile phases
which is based on the polarity of the three components. Polar compounds will interact
63
more strongly with polar solvents and the polar stationary phase than nonpolar compounds
and vice versa.
Retention Index
The amount of interaction is determined by the retention index (Rf) which is defined as the
ratio of the distance the spot moved over the distance the solvent moved (solvent front).
Rf values close to 1 indicate that there was a stronger interaction with the solvent than the
stationary phase and conversely, Rf values close to 0 indicate that there was a more
favorable interaction with the stationary phase.
Salicylic Acid Ethanol
Similar results are provided for toluene, 1:9 ethyl acetate:toluene, 1:19 ethyl
acetate:toluene.
64
Follow-Up Laboratory Questions
These questions can be used in a variety of different ways ranging from group work,
to homework, quiz questions, or exam questions. At Clemson, group work and
Concept-Test format was implemented.
1.
An Rf of 1 indicates which of the following?
a. the compound interacts strongly with the stationary phase
b. the compound interacts strongly with the mobile phase
c. there is equal interaction
d. the compound is reacting with the solvent
For 2 - 3 use structures A – D.
O
O
OH
O
H
A
B
C
D
2.
Using silica gel TLC plates and toluene as the eluent, __ would have the greatest
Rf.
3.
The Rf of C would be fairly close to __ using silica gel TLC plates and
dichloromethane as the solvent.
Cl
4.
Cl
Given the reaction:
OH
Cl
Cl
Which of the following diagrams indicates the most probable result if a TLC plate was
spotted with the starting material (the left spot) and the product (the right spot)? Note:
Dichloromethane was used as the development solvent.
A
B
C
D
65
In-Stereo
Problem Description
Stereochemistry requires students to be able to visualize three dimensional space
and often requires the use of molecular models. This problem will allow students to view
various molecular models including wireframe, space fill, Lewis structure, Newman
projections, and ball-and-stick to determine the absolute configuration of a chiral molecule.
The problem also requires students to identify the Fischer projections for the enantiomers
of this molecule.
Problem Goals and Objectives



What models do students prefer when solving stereochemistry problems? Are these
models effective?
How well do students under the Cahn-Ingold-Prelog rules? This can be determine by
whether students use the library information, as well as, whether they make analogous
errors in solving the problems.
The underlying goal of this problem is to determine what models should be
implemented when introducing stereochemistry to students.
Number of Different Cases
6
Cl
Cl
CH 2I
O
OH
SH
OH
O
Implementation
The problem should be implemented following the lectures on stereochemistry. At
Clemson, we used the problem after completing Chapter 5 in Bruice’s Organic Chemistry
text.
66
What Information is Provided for Students
Available Materials
a.
Line Structure
b.
Lewis Structure
c.
Newman Projection
d.
Sawhorse Projection
67
e.
3-D Structure (Ball & Stick)
f.
3-D Structure (Wireframe)
g.
3-D Structure (Space Fill)
68
h.
3-D Structure (Stick)
i.
Chime Structure
The last model available uses a chime plugin to allow students to rotate
molecules in 3-D space.
Library Information
a.
Cahn-Ingold Prelog Rules
The substituent with the highest atomic number has the highest priority.
In cases in which there is an identical substituent such as a carbon and oxygen, the
rules state the we must look at the substituents on these atoms. For instance, -OH has
lower priority than -OCH3 because carbon has a greater atomic number than hydrogen.
Likewise, -CH2CH2R has lower priority than -CH(CH2)R' regardless of the identity of R or
R'.
For alkenes and alkynes, the number of carbon - carbon bonds is considered. For
alkenes, there are 2 carbon-carbon bonds and for alkynes, there are 3 carbon-carbon
bonds. Therefore, alkenes and alkynes will take precedence over CH2CH2R groups
because carbon has a greater atomic number than hydrogen.
In summary to assign priority we look for the highest atomic number. In the case of chains
and rings, we identity the first difference in the rings or chains and ignore the rest of the
substituents.
69
b.
Rules for Assigning R/S
Orient the lowest priority group so that it points away from you.
Then determine the orientation of the substituents.
If the substituents move from highest to lowest priority in a clockwise direction, the
molecule has an R absolute configuration.
If the substituents move from highest to lowest priority in a counterclockwise direction,
the molecule has an S absolute configuration.
c.
Tutorial
Given the following structure, what is the absolute configuration?
1.
Which group has the highest priority?
-NH2
-CH3
-H
-C(CH3)3
2.
Which group has the second highest priority?
-NH2
-CH3
-H
-C(CH3)3
70
3.
From highest to lowest priority, what is the direction of rotation?
Counterclockwise
Clockwise
4.
Based on your answer above, assign the R and S configuration.
R
S
The tutorial is available for students who are having trouble with the fundamental ideas
and concepts.
Answer List
1. The absolute configuration is R or S ?
2. Select the correct fischer projections for the enantiomer.
1.
2.
3.
4.
5.
6.
When solving the problem, students will be given a string of possible solutions such as R,
1, 2, 3 representing the R configuration and Fischer projections 1 – 3.
71
Organo-Mech
Problem Description
Organic mechanisms (SN1, SN2, E1, E2) often give students difficulty. This an
interactive problem dealing specifically with these four mechanisms.
Problem Goals and Objectives




Identify what information students feel is relevant in determining the mechanisms.
What information do students employ to differentiate between first order and second
order reactions?
What information do students employ to predict the results of competition between
substitution and elimination reactions?
What information do students employ that is irrelevant and not useful? This will identify
possible alternate conceptions that students hold concerning these problems.
Number of Different Cases
8
Two cases for each of the four mechanisms: SN1, SN2, E1, E2
Implementation
The problem is best implemented in the first semester organic chemistry course
following the introduction to these mechanisms.
At Clemson, we used these problems after completing chapters 10 and 11 in the
Bruice Organic Chemistry text (4th edition).
What Information is Provided for Students

Available Information
1. Molecular Formula of Reactant and Product
2. Substrate Type (most cases are secondary)
3. Kinetic Data
4. Solvent
5. Leaving Group (examples include water, tosylate, chloride)
6. Nucleophile
7. Reaction Time
8. Volume of Reaction Container
9. Temperature of the Reaction
10. Rotation of Plane Polarized Light of Reactant and Product
72

Library Information (as given to the students)
Substrate
Sn1
Secondary, Tertiary,
Allylic, or Benzylic
Sn2
Primary, Secondary
E1
Secondary, Tertiary,
Allylic, or Benzylic
E2
Primary, Secondary
Rate Law
Sn1
Rate = k[Org]
Sn2
Rate = k[Org][Nuc]
E1
Rate = k[Org]
E2
Rate = k[Org][Nuc]
Solvent
Sn1
Protic, High Dielectric
Constant
Sn2
Polar, Aprotic
E1
Varies
E2
Polar, Aprotic
Intermediate
Sn1
Carbocation
Sn2
Concerted Reaction
E1
Carbocation
E2
Concerted Reaction
Leaving Groups
Sn1
Good leaving groups (e.g.
weak bases) are favored
Sn2
Not Applicable
E1
Good leaving groups (weak
bases) are favored
E2
Not Applicable
Stereochemistry
Sn1
Racemization results
Sn2
Inversion Results
E1
N/A
E2
N/A
Rearrangements
Sn1
Rearrangement can occur
Sn2
Rearrangement is not observed
because a carbocation is not
formed.
E1
N/A
E2
N/A
Energy Diagram
Sn1
Sn2
E1
E2
Competition between Substitution and Elimination
Base Strength:
Temperature:
Strong bases favor elimination
Elevated temperatures favor elimination
73
Definitions
Aprotic: solvent that does not have protons that can be easily removed. Examples include
dichloromethane, toluene, and acetonitrile.
Protic: solvent that has protons that can be removed easily. An example is ethanol and
water.
Dielectric constant: measure of how well the solvent will moderate the attractive forces of
the electrophile and nucleophile. The greater the diaelectric constant, the better the
medium to support the formation of the carbocation intermediate.
Polarizable: this describes how tightly an atom holds on to its electrons. Fluorine atoms
are not polarizable because the electrons are tightly centered around the
nucleus, but iodine atoms are polarizable because the electrons are not held in place as
tightly.
Leaving Group: A group that is lost from the starting organic substrate. These groups are
typically weak bases. Examples include: tosylate, water, iodide, bromide, and
chloride
Primary carbon: a carbon that is attached to one carbon and three hydrogens.
R
H2C
CH3
the primary carbon is enclosed in a box
Secondary carbon: a carbon that is attached to two carbons and two hydrogens.
R
CH2
CH3
the secondary carbon is enclosed in a box
Tertiary carbon: a carbon that is attached to three carbons and one hydrogen.
CH 3
RH 2C
C
CH 3
H
the tertiary carbon is enclosed in a box
Allylic carbon: a carbon that is alpha to a double bond.
R
CH2
the allylic carbon is enclosed in a box
74
Benzylic carbon: a carbon that is alpha to a benzene ring.
CH 2
R
the benzylic carbon is enclosed in a box
Tutorial: This will provide students with an opportunity to assess their understanding of
information presented in the library.
Tutorial Questions
[1.] Identify the type of carbocation (the location is indicated with an arrow) that would form from the loss of
the chlorine group:
(i) a)
Benzylic b)
Allylic c)
Methyl d)
Primary e)
Secondary f)
Tertiary
(ii) a)
Benzylic b)
Allylic c)
Methyl d)
Primary e)
Secondary f)
Tertiary
(iii) a)
Benzylic b)
Allylic c)
Methyl d)
Primary e)
Secondary f)
Tertiary
(iv) a)
Benzylic b)
Allylic c)
Methyl d)
Primary e)
Secondary f)
Tertiary
(v) a)
Benzylic b)
Allylic c)
Methyl d)
Primary e)
Secondary f)
Tertiary
(vi) a)
Benzylic b)
Allylic c)
Methyl d)
Primary e)
Secondary f)
Tertiary
75
[2.] Check the protic solvents in the following list:
Chloroform
Dicholoromethane
Ethanol
Benzene
Formic Acid
Hexane
Dimethyl Sulfoxide
Dimethyl formamide
[3.] Check the statement that is true about leaving groups:
The best leaving group are strong bases
The best leaving groups are strong acids
The best leaving groups are weak bases
The best leaving groups are weak acids
[4.] Check the statement that is true about nucleophiles:
The best nucleophiles are strong bases such as RO- and NH2The best nucleophiles are strong acids such as HCl
The best nucleophiles are weak bases such as IThe best nucleophiles are weak acids such as a carboxylic acid
76
[5.] Check the statement that explains why I-is a better nucleophile than Cl-:
I-is a stronger base than ClIodine is more electronegative than Chlorine
The I-ion is less solvated than the Cl-ion
Cl- is more polarizable than I[6.] Rank the following in terms of leaving group ability:
1=Best Leaving Group 4=Worst Leaving Group
H2O
TosOFI[7.] a. Rate = k[Organic Substrate][Nuc-]
b. Rate = k[Organic Substrate]
c. Rate = k[Organic Substrate]2
d. Rate = k[Organic Substrate]2[Nuc-]
The expression above that corresponds with SN1 rate law
The expression above that corresponds with SN2 rate law
[8.] Check each true statement in the following list:
The attack of the nucleophile is the rate determining step in an SN1 reaction.
The SN1 reaction yields streochemical inversion.
Bimolecular is another name used to describe an SN2mechanism.
77
The properties of nucleophile are more important in SN2 reactions than in SN1 reaction.
The loss of the leaving group is the rate determining step in an S N1 reaction.
There are no intermediaries formed in an SN2 mechanism.
The following energy diagram can be used to describe an SN1 mechanism:
78
Spectra Analysis
Problem Description
This problem focuses on elucidation of organic structures using spectroscopic data.
Problem Goals and Objectives




Identify which pieces of spectroscopic information student rely upon the most. Do they
rely upon all available information or just selected information?
What types of example spectra do students elect to view? What functional groups are
present in these spectra?
Do students use the correlation charts? If so, what kind of charts do student rely upon
the most?
What characteristics of organic compounds give students the most trouble when
interpreting spectra? What types of compounds are most easily elucidated by
students?
Number of Different Cases
15
Cyclohexanone
Diallyl Ether
1-Hexyn-3-ol
1-Ethynylcyclopentanol
3-methyl-2-cyclohexa-1-one
Dicyclopropyl Ketone
3,5-Heptadiene-2-one
Ethoxybenzene
o-ethyl phenol
o-methoxy toluene
2-pentanol
1-penten-3-one
Cyclopentanone
1-pentyn-3-ol
5-hexene-2-one
Implementation
This problem is best implemented in either lab or lecture after a unit on
spectroscopy covering interpretation or IR, 1H NMR, and 13C NMR. Students should also
be comfortable with identifying the molecular ion peak in mass spectrometry data.
What Information is Provided for Students
79
Library
a.
13C
b.
1H
Correlation Data
Correlation Data
80
c.
IR Correlation Chart
IR correlation chart
81
d.
Mass Spectrometry Correlation Data
e.
Periodic Table
82
Examples
NMR, IR, and MS data is provided for each of the following compounds as a reference of
actual examples for students to use.
1-nitropropane
2-butanone
2-methyl-1-butene
benzaldehyde
benzene
diethyl ether
methanol
propionamide
propanoic acid
Available Equipment
a.
13C
Spectrum
Actual Example:
83
b.
Mass Spectrum
Example:
c.
1H
NMR Spectrum
Example:
84
d.
IR Spectrum
Example:
Comments about the Spectra:
The resolution of the NMR spectra is not the best; however, we feel that students need to
be exposed to non-textbook style examples. The spectra are clear enough for students to
obtain general idea about peak shape, and the chemical shift information is very clear.
The integration is not provided because students should be able to solve the problem
without this information. There are only 15 possible solutions, and the integration would
enable students to “game” the problem, and make a reasonable guess just on the basis of
the 1H NMR. The objective of the problem is to require students to piece together
information from several spectra—not just NMR.
Solvent Issues
85
13C-NMR
1H
solvent issues
– NMR solvent issues
Additional Comment:
The solvent signals have been removed from the spectra, but we wanted to reassure
students that the peaks in the NMR are associated with the molecule of interests and not
associated with unrelated noise.
86
Hints/Formula
a.
Possible Formula List
b.
13C
- Hints
87
c.
1H
d.
Degree of Unsaturation
NMR Hints
88
e.
IR Hints
f.
MS Hints
89
Finding Carbon’s Neighbors
Problem Description
This content of this problem focuses on the use of qualitative organic tests to
identify an organic unknown. Spectroscopic data is not provided. Examples of the
qualitative tests include:










Tollens’ Test
Hydroxamic Acid Test
Baeyer Test
Iodoform Test
Ignition Test
Prussian Blue Test
Lucas Test
Chromic Acid Test
Ferrox Test
Reaction with Bromine and Water
Problem Goals and Objectives




Identify how students begin such unknown type analysis. Where do students start?
Obtain information to identify how students piece together information concerning
functionality to identify an unknown.
Provide students with exposure to qualitative methods commonly omitted in most
organic laboratories today.
Make a connection between lecture, where many of these reactions are taught, and
lab.
Number of Different Cases
24
Acetamide
4-Hydroxy- 3-methoxy-benzaldehyde
Chloroacetic Acid
2-Heptanone
4-nitrophenol
1-Heptene
2-chloro-benzaldehyde
2-nitro-1-methoxybenzene
1-chloro-2-propanol
Benzoyl Chloride
2-Aminoheptane
Pyrrolidine
Benzyl Alcohol
Propyl Acetate
4-chlorophenol
4-chloro-cyclohexanone
Isopentyl Acetate
Maleic Acid
3-nitroacetophenone
Acetanilide
2-pentanol
3-chlorotoluene
90
cycloheptanone
E-cinnamyl alcohol
Implementation
The problem is best implemented in a second semester organic laboratory
sequence after students have learned about carboxylic acids and esters in lecture because
carbonyl chemistry is well represented in this problem.
At Clemson, we used this problem in the last two weeks of the laboratory. This
problem was initially implemented in conjunction to a similar unknown type analysis that is
provided. In subsequent semesters, the problem was successfully implemented without
prior laboratory experience. We required students to work a minimum of 5 problems – four
of which must be answered correctly in order to receive full credit.
What Information is Provided for Students

Various Chemical Reactions
This information is presented in terms of color changes associated with positive
results or students are informed that there is no visible reaction.

Solubility Data
This information is presented in terms of whether the compound is soluble, slightly
soluble, or insoluble.

Physical Data
This includes melting point, boiling point, color, odor, and physical state. All of this
information would be accessible to students in the laboratory.

Combustion Data
This is provided to enable students to narrow down from the 24 possible choices in
order to provide them with a more manageable working space.

Library of Information
Includes all pertinent information concerning reactions (positive and negative
results) and solubility.
Average Solve Time
20 Minutes
91
Laboratory Experiment Implemented at Clemson University
CH 228 | Adv. Organic Chem. Lab | Qualitative Organic Analysis | Project 3
Written by Melanie M. Cooper and Charlie Cox
Project Description:
You are working for a new company and finally making big bucks. Everything is
great until one day you are asked to obtain an up-to-date inventory of all of the chemicals
in your department. All goes well until you find a single bottle in which the label has been
removed. You check the old inventory list (that was taken two months ago) and conclude
that it must be one of the 12 compounds that has not been located. Knowing how easy it
is to obtain and analyze NMR you prepare an NMR sample and head to the 500 MHz NMR
to quickly finish your task by the deadline. However, to your dismay the NMR is down and
the computer for the FTIR is being replaced. The only option is qualitative organic analysis
methods. Knowing your boss, he will not accept just melting point or boiling point data.
Work quickly and efficiently to reach the deadline. The first task is to prepare a detailed
written proposal explaining exactly how to proceed.
Possible Compounds:
Benzaldehyde
Acetaldehyde
Benzyl Alcohol
Acetanilide
m – nitro Benzoic Acid
Aniline
Benzoic Acid
Benzophenone
Diethyl Malonate
Nitrobenzene
Methyl Benzoate
Maleic Acid
Possible Tests:
Tollens Test
Chromic Acid Test
Iodoform Test
Reaction with 2,4-DNP
Hydroxamic Acid Test
Ferrous Hydroxide Test
Baeyer Test
Lucas Test
Reaction with Silver Nitrate
Beilstein Test
Ignition Test
Others may be used with permission
92
Proposal | Pre - Lab:
Write a descriptive summary of how you plan to identify your unknown.
 What tests do you plan to use? Why?
 In what order will you use them?
 Provide a description of how to conduct each test you plan to use.
o Include the order in reactions are mixed.
o The mole and gram or mL quantities of all reagents.
o Techniques needed such as refluxing or filtering.
o Provide a summary for each test explaining what to expect for a positive
result and a negative result.
 Provide a brief summary of the hazards associated with each test.
The proposal is to be typed (double – spaced, 12 pt font). The proposal should be
between 2 and 4 pages typed.
Grading Criteria:
Item
Excellent
Good
Fair
Poor
Test Scheme with a Description (6)
Complete Experimental Description (8)
Hazard Summary (3)
Scientific Strategy and Planning (3)
93
Laboratory Report | Qualitative Organic Analysis
1.
Outline the tests used for the analysis and briefly describe their results.
2.
Based upon the results outlined above, what conclusions can be drawn
concerning the functional groups present?
3.
Unknown Code __________________
Unknown Name_________________________________________
Unknown Structure
4.
Which tests did you find to be the most useful? Least useful? Why?
5.
In future experiments, briefly explain how you would alter your procedure or
explain why you would not alter your procedure.
94
Qualitative Organic Analysis – Library Information
Alcohols
Chromic Acid Test – a primary or secondary alcohol will reduce the orange – red
chromic acid/sulfuric acid reagent to an opaque green or blue suspension of
Cr (III) salts.
Lucas Test – The Lucas reagent is formed by adding ZnCl2 to concentrated HCl
a.
Tertiary – alkyl halide formation is identified by the formation of an
insoluble layer or emulsion. This will take place in less than a minute.
b.
Secondary – same result but a longer period of time (5 – 10 minutes)
is needed for the reaction to take place.
c.
Primary – No Reaction
Iodoform Test – a yellow precipitate of iodoform appears within 15 minutes.
Aldehydes/Ketones
Reaction with 2,4-dinitrophenylhydrazine – formation of a large amount of
yellow to red insoluble 2,4-dinitrophenylhydrozone indicates the presence
of an aldehyde or ketone.
Chromic Acid Test – Oxidation of an aldehyde is possible using this reagent.
The orange – red chromic acid/sulfuric acid reagent will turn to an opaque green
or blue suspension of Cr (III) salts.
Iodoform Test – a yellow precipitate of iodoform appears within 15 minutes in the
presence of an aldehyde or ketone.
Tollens Test – a silver mirror or colloidal silver appears in the presence of either an
aldehyde or ketone.
95
Alkenes
Reaction with Bromine – alkenes react with bromine and the characteristic
color (dark red/brown) of bromine disappears.
Oxidation with Potassium Permanganate – the purple color of the permanganate
solution is replaced within 2 – 3 minutes by a brown precipitate of manganese
dioxide.
Alkyl Halide
Reaction with Silver Nitrate – the formation of a precipitate of (silver halide) is a
positive indicator for the presence of an alkyl halide. The precipitate usually
has a white coloration.
Reaction with Sodium Iodide – the formation of an obvious precipitate of sodium
chloride and sodium bromide is a positive test.
Aromatic Hydrocarbons
Ignition Test – Aromatic compounds general burn with a smoky flame.
Reaction with Aluminum Chloride/Chloroform – a color change of the
powder and the solution indicates a positive job.
Amines
Prussian Blue Test – a dark blue precipitate is formed in the presence of
an amine or any other compound containing nitrogen.
Reaction with HCl – amines will react with HCl.
96
Nitro Compounds
Prussian Blue Test – a dark blue precipitate is formed in the presence of
a nitro group or any other compound containing nitrogen.
Ferrous Hydroxide Test – a dark red solid precipitate is formed in the presence
of a nitro group.
Esters
Hydroxamic Acid Test – a positive test for an ester is the formation of a blue or red
colored precipitate.
Ethers (and all of other functional groups that contain oxygen)
Ferrox Text – a red to reddish purple color appears if the unknown contains oxygen.
Phenols
Reaction with Bromine/Water – the disappearance of the characteristic dark red/brown
color of bromine is a positive indication for the presence of a phenol.
Reaction with Ferric Chloride – most phenols react with Ferric Chloride to form a red to
blue ferric phenolate complex.
97
98