Applied Laboratory Manual
Reporting Sheets
Part A
This record book belongs to: …………………………………….
Contents
Workplace protocols ................................................................................................... 3
Report Writing ............................................................................................................ 4
Quality Principles........................................................................................................ 6
Quality Concepts in the goods and services workplace ............................................. 8
Glossary of Quality Terminology ................................................................................ 9
Measurement of Quality ........................................................................................... 10
Relative and Absolute Descriptions of Error ......................................................... 11
Errors and Limits of Reading .................................................................................... 12
Practical 5.2B Calibration of Laboratory Balances ................................................... 13
Practical 5.3C Calibration of Volumetric Glassware ................................................. 14
Practical 5.7A Temperature Calibration.................................................................... 18
Practical 7.2
pH Meter Calibration ...................................................................... 19
Practical 7.5
Refractive Index Calibration ........................................................... 20
Practical 7.3a
Calibration of Kohfler Hotbench ..................................................... 21
Practical 6.1
Validation of sampling .................................................................... 24
Boiling Point ............................................................................................................. 30
Rules for Distillation.................................................................................................. 31
Preparation and Purification of Ethanol .................................................................... 35
Other Distillation Methods ........................................................................................ 38
Practical Observation of Fractional Distillation ......................................................... 39
Practical Observation of Steam Distillation............................................................... 42
Practical Observation of Vacuum Distillation ............................................................ 44
Practical 7.3 Mixed Melting Point ............................................................................. 46
Practical 7.5 Refractive Index .................................................................................. 49
2
Workplace protocols
1. Safety Procedures
(a)
(b)
(c)
(d)
(e)
(f)
(g)
Consult Safety Data sheets* and
method of analysis for advice on
hazards and precautions to be taken
Wear appropriate PPE
Use fume hood etc as necessary
Maintain tidy workspace
Exercise care not to endanger other
people
Observe emergency procedures
Report spillages and all accidents
2. Recording and Reporting
Register samples into laboratory
system
(b) Label samples
(c) Record which tests the sample
should undergo
(d) Record sample description,
compare with specification, record
and report discrepancies
(e) Record calibration results for
instruments/equipment in tables
and/or charts, following quality
system
(f) Keep records of calibration status
and calibration schedule for
instruments / equipment
(g) Report faulty equipment
(h) Keep records of solutions prepared,
by expected use-by date, and by
name of person who prepared them
(i) Record results legibly, and chart
when required to identify trends
(j) Interpret trends
(k) Identify and report atypical results
promptly to appropriate personnel
(l) Record approved results into
workplace system
(m) Comply with quality system
(n) Report all accidents and potential
hazards
(o) Maintain confidentiality of workplace
information
3.
Sample Handling
(a)
(b)
Maintain sample integrity
Prepare sample and standards for
test
4.
Testing
(a)
Refer to workplace procedures
manual for standard method
Conduct tests according to
workplace procedures
Clean up spills promptly
Record results according to
workplace procedures, without
alteration
Calculate results, checking
against expected values and
correcting errors
Trouble shoot basic problems with
procedure or equipment which
have led to atypical results
(b)
(c)
(d)
(a)
(e)
(f)
5.
Equipment and Reagents
(a)
(b)
(g)
Set up equipment and reagents
Check calibration status of
equipment; calibrate if necessary
Monitor shelf-life of working
solutions
Prepare solutions when
necessary, label and log into
laboratory register
Clean and care for test equipment
and work space
Dispose of faulty equipment or
quarantine it for repair
Store unused reagents
6.
Wastes
(a)
(b)
Minimise generation of wastes
Collect, sort and dispose of
wastes in accordance with
procedures
(c)
(d)
(e)
(f)
* SDS’s were up until January 1 2012
referred to as MSDS (Material Safety
Data Sheets)
3
Report Writing
Written laboratory reports can take may formats. The general format that is required
in the CFFET section is as follows.
Prework
Some practicals require Prework which must be completed prior to the lesson. The
Prework should be kept in your logbook book or on the appropriate worksheet. . This
must be checked and initialled by the teacher.
1. Summary
A conclusion at the start of the experiment, containing the following information in no
more than 6 lines
 WHAT SAMPLE was analysed
 WHAT RESULTS were obtained
 WHAT METHOD was used
An example for the determination of iron in wine would be:
―A sample of wine was analysed for its iron content using UV-vis spectrophotometry.
The iron content was found to be 15 mg/L.‖
2. Results
A results sheet for each experiment, which provides for the collection of data
necessary for the experiment, is included in this manual. This must be included in
the practical report. It is not necessary to rewrite the results.
3. Calculations
Most experiments will have a detailed section of the calculations necessary for the
report. It is not necessary for you to follow the instructions exactly, but you must
show your method of calculation.
If you cannot understand how to approach a calculation, see your teacher. The point
of writing up reports is not just to get you through the subject, but to learn how to
carry out chemical calculations.
Calculations in the report should:




be clear and tidy
be shown in full (except in the case of duplicates, which need to only have the
final answer shown)
contain all units at all times (in SI, unless otherwise stated)
show relative precision data, where possible.
When working with solution concentrations, there are a number of different units that
are commonly used eg molarity, grams/litre, grams/100 mL (the same as %w/w),
ppm (the same as mg/L and ug/L) etc. The experiment will indicate which unit is
required.
4
When graphing of results is necessary in the experiment, you will be encouraged to
use computer-based facilities for the drawing of the graphs. It will be possible,
however, to submit hand drawn graphs.
4. Discussion
Should include explanations to points in the practical and the following:
 a statement of your final results
 comparison with standard results, where possible
 problems encountered and possible solutions
 your comments on the advantages and disadvantages of the technique for the
task
 other analytical methods that would be suitable for the analysis
Some experiments will indicate other aspects that must be included in the
discussion. A suitable discussion would take up to one and a half pages.
5. Questions
These will generally involve looking at references other than the practical results.
Your overall mark will reflect the answers that you give.
Useful References
You are encouraged to read further, the recommended texts for background theory,
Vogel’s Textbook of Quantitative Analysis for details of the practical chemical
analysis and Chemistry in the Marketplace by Ben Selinger, which provides a
chemical background to most consumer products.
5
Quality Principles
What does quality mean to you?
Write your understanding of the word ―quality‖ as it applies to the following:
(a)

quality car

quality food

quality service

quality education
QUALITY is ultimately defined by the customer – they will decide if they like your
product / services and whether they will buy it again. If they don’t like it they could
speak badly about it to all who will listen and so effectively destroy future sales.
QUALITY is the customer's expectation of what they should be getting for their
money. If the goods or services match or exceed this expectation, it is seen as
quality by the customer. Customer expectations include such things as:
6
Suppliers of goods and services often have to anticipate customer expectations as
they create or design or fine tune their products and services.
How do you think public and commercial organisations find out about their
customers’ expectations for goods and services?
How do you think public and commercial organisations make sure that their
customers’ expectations for goods and services are being met all the time?
Who are the customers of CFFET - this science section of TAFE?
How do you think CFFET finds out about the expectations of each group of its
different customers’?
7
Quality Concepts in the goods and services workplace
Quality depends on





In-house and industry standards – describe what the customer wants and
expects of their purchase. This could be cost, taste, colour, reliability, ease of
repair or replacement, size, consistency, crispness, freshness, etc, etc, etc
conformance to these in-house and industry standards by each production unit.
Normally these standards are listed as measurable specifications for the factory
to use to decide if the taste, colour, safety, coding, etc are meeting the standards
Legal standards (eg weight, contents, nutritional data, date codes, marketing
ethics, etc)
safety standards (child safe, heart safe, no germs or toxins, warnings, etc)
other factors
Attainment of quality is a never ending cycle of before, during and after production of
the goods or services.
Before implies before production and includes your market research and the
planning associated with sourcing of raw materials, manufacturing systems,
equipment and procedures, packaging and distribution.
During implies during production and systems to ensure that every unit of production
is likely to meet the set standards and customer expectations.
After implies after production and includes customer inquiries and complaints
(customer service), analysis of data and what it means for quality improvement, etc
There are many definitive cycles used by the workplace to effect improvement. One
widely use cycle is the plan / do / check / act cycle. This will be examined more in
Semester 2.
Quality management in an organisation often also includes:





impact on the environment (waste management and recycling, re-use, etc)
customer health and safety
worker health and safety
production methods, material handling systems, work instructions, etc
enterprise systems of work such as purchasing, customer service, production,
planning, marketing, financial matters and so on.
8
Glossary of Quality Terminology
There are a number of terms widely used to describe the attainment of quality in the
workplace.

Conformance/ non conformance/ compliance/non-compliance

quality product

quality raw materials

quality control

quality assurance

quality management /TQM

quality systems

quality accreditation eg ISO
9
Measurement of Quality
You need to complete this case study of quality in a fruit and meat pie making
business which sells fresh and frozen pies to supermarket chains, clubs and various
retailers, as well as customers who come to his site.
This caring business owner is seeking your advice about how his business can
supply his customers with a quality range of products. What advice can you give this
business about:

Control of Quality (during production to decide which pies are saleable or not)

Assurance of Quality (the planning and analysis needed to be sure you are in
control, and that only saleable pies leave the site)

Management of Quality (systems, resources and procedures to ensure on going
quality is always going to happen)
10
Relative and Absolute Descriptions of Error
The absolute error (or absolute accuracy) is the difference between the observed
value and the true value.
The relative error (or relative accuracy) is the absolute error expressed as a
percentage of the accepted value. The sign of the error may be positive or negative,
indicating that
the result is high or low respectively.
The absolute precision is half of the range of the measurements.
The relative precision is the absolute precision expressed as a percentage of the
mean of the measurements.
These definitions are summarised in the Table below
Definitions and formulae used to describe errors
Symbol
Interpretation
Formula
X
A measured or observed value
x1 , x2, x3, etc. for all your readings
R
The range from biggest to smallest of all
replicates for this measurement
R = x biggest – x smallest
µ
The average of all replicates for this
measurement
µ = [x1 + x2 + x3 + … ]
number of replicates
X true
The true or correct value
Eabs
The absolute error or accuracy
Erel
The relative error or accuracy
Eabs
= X – Xtrue
Eabs
= µ – Xtrue
Erel
=
Eabs
or
× 100
Xtrue
R  2
Pabs
The absolute precision
Pabs
=
Prel
The relative precision
Prel
= Pabs × 100
µ
11
Errors and Limits of Reading
The uncertainty of any reading is half the value of the smallest scale division. Thus
if your smallest scale division is one unit your answer can be shown as  0.5 unit.
Reading scales and assigning uncertainty
Read the scales below and write down your readings for the position of the pointer in
each case. There are no units required. Assign an uncertainty figure to each of your
scale readings. Use  after the value for each reading.
a
b
h
n
c
i
o
d
j
p
e
k
g
l
q
r
(a)
(h)
(o)
(b)
(i)
(p)
(c)
(j)
(q)
(d)
(k)
(r)
(e)
(l)
(s)
(f)
(m
)
(n)
(t)
(g)
f
m
s
t and u
(u)
12
Practical 5.2B Calibration of Laboratory Balances
Date Completed:
___________________ Teacher check _____________
Purpose
Analyst signature _______________
To become familiar with a range of laboratory balances and assess their
performance using a range of standard masses.
Results
Observed values for standard masses
Balance
specifications
Mass (g)
of 1.000
g
% Error
Mass (g)
of
50.0000
g
% Error
Mass (g)
of
100.000
g
% Error
Questions
1. Calculate the percentage error for each mass on each balance
2. What rules should there be for the care and handling of the calibration
masses?
3. What corrective actions exist for dealing with a faulty balance?
4. What corrective actions exist for dealing with faulty calibration masses?
13
Practical 5.3C Calibration of Volumetric Glassware
Date Completed:
___________________ Teacher check _____________
Purpose
Analyst signature _______________
To become familiar with a range of laboratory volumetric devices and assess their
performance using simple calibration procedures
Results
Water Temperature
1. Correct Use of volumetric Glassware
Name of
volumetric device
Sacrificial rinse
Density of water =
Pipette
Burette
Volumetric flask
Fill and adjust to
zero
Deliver specified
volume
Not applicable
Teacher sign off
2. Pipette
Pipette size (mL)
First
attempt
Second
attempt
Third
attempt
Fourth
attempt
Empty container mass
(g)
Container plus water
mass (g)
Mass of water
(g)
Volume of water
(mL)= mass / density
Absolute error
Relative error
Stated tolerance
14
3. Volumetric flask
Volumetric flask
volume (mL)
First
attempt
Second
attempt
Third
attempt
Fourth
attempt
First
attempt
Second
attempt
Third
attempt
Fourth
attempt
Empty container mass
(g)
Container plus water
mass (g)
Mass of water
(g)
Volume of water
(mL)= mass/density
Absolute error
Relative error
Stated tolerance
4. Burette
Name of volumetric
device
Empty container mass
(g)
Container plus water
mass (g)
Mass of water
(g)
Volume of water
(mL) = mass/density
Absolute error
Relative error
Stated tolerance
15
5. Autopipette (100 µL)
Temperature
= _______________
Density
=________________
Total Mass (g)
Empty sample
vial
1
Difference (g)
------
2
3
4
5
6
7
8
9
10
Average (g)
------
Avg (mL)
=mass/density
Amount in uL
(Avg x 1000)
-----------
16
Conversion of mass of water to volume of water via its density at different
temperatures
temperature
density
temperature
density
0
999.8395
1
999.8985
21
997.9925
2
999.9399
22
997.7705
3
999.9642
23
997.5385
4
999.9720
24
997.2965
5
999.9638
25
997.0449
6
999.9402
26
996.7837
7
999.9015
27
996.5132
8
999.8482
28
996.2335
9
999.7808
29
995.9448
10
999.6996
30
995.6473
11
999.6051
31
995.3410
12
999.4974
32
995.0262
13
999.3771
33
994.7030
14
999.2444
34
994.3715
15
999.0996
35
994.0319
16
998.9430
36
993.6842
17
998.7749
37
993.3287
18
998.5956
38
992.9653
19
998.4052
39
992.5943
20
998.2041
40
992.2158
Steps for calculating your true volume
1. Select the temperature which most closely matches your water's temperature
2. Find the density value in the table which corresponds to this temperature
3. For each of your measured masses of water, enter the numerical value for mass
into your calculator
4. divide this value by the density figure from the table
5. multiply by 1000 (to compensate for density being shown as kg / m3)
6. your display will now show your true volume for that mass of water.
7. Enter this value into you manual result sheet.
17
Practical 5.7A Temperature Calibration
Date Completed:
___________________ Teacher check _____________
Purpose
Analyst signature _______________
To calibrate a thermometer typically in use in CFFET laboratories.
Results
Thermometer
range
Reference
Material
Low
temperature
Recorded
temperature
High
Temperature
Recorded
Temperature
Questions
1.Why is it important that a reference material is available to calibrate a
thermometer?
2. Were all the thermometers you tested found to be within specification?
3. What is the workplace procedure for thermometers that fall outside
specification?
18
Practical 7.2
pH Meter Calibration
Date Completed:
___________________ Teacher check _____________
Purpose
Analyst signature _______________
To become familiar with the method of calibration of laboratory pH meters.
Results
2 Point Calibration
Temperature of solution
pH 7 buffer
Asymmetry
Slope
pH 4 buffer
Asymmetry
Slope
pH 7 buffer
Asymmetry
Slope
pH 4 buffer
Asymmetry
Slope
pH 7 buffer
Asymmetry
Slope
pH 4 buffer
Asymmetry
Slope
pH 7 buffer
Asymmetry
Slope
pH 9 buffer
Asymmetry
Slope
pH 7 buffer
Asymmetry
Slope
pH 9 buffer
Asymmetry
Slope
pH 7 buffer
Asymmetry
Slope
pH 9 buffer
Asymmetry
Slope
Laboratory sample
Laboratory sample
19
Practical 7.5
Date Completed:
Refractive Index Calibration
___________________ Teacher check _____________
Purpose
Analyst signature _______________
This exercise will develop the skills needed to calibrate a refractometer
Results
Refractive index of pure of solvents with known RI:
Substance
Initial
RI reading
Temperature
of sample
Temperature
Corr. factor
Termperature
Corrected RI
Instrument
correction
(using water
@ 20oC
value of
1.333
Final
Corrected
value RI
Water
Trichloromethane
Questions
1. Why is it necessary to calibrate a refractometer before use?
2.
What happens to the refractive index of a liquid as its temperature rises?
3.
Why must the prisms only be cleaned and dried with soft tissue paper?
4.
Why are refractive indices corrected to 20C?
5.
How many decimal places can be read from the refractometer?
20
Practical 7.3a
Calibration of Kohfler Hotbench
Date Completed:
___________________ Teacher check _____________
Purpose
Analyst signature _______________
To calibrate a Kofhler Hotbench using calibration standard materials
Results
Reference Material Identity
Expected Melting point
Melting point on hotbench
Adjustment of pointer required
Yes / No
Repeat check of melting point
21
Practical work 5.4B
Date Completed:
Advanced work with solution preparations
___________________ Teacher check _____________
Purpose
Analyst signature _______________
To prepare a serial dilution set of standards and then validate the preparation by
comparison to a sample prepared by laboratory staff. If the solutions do not meet the
necessary tolerances, they will need to be remade.
Procedure
Using an analytical balance accurately weigh out the mass of each solute listed in
the work sheet. (For hydrochloric acid, dilution by pipette is required).
Quantitatively transfer the solid to a 100mL volumetric flask and make up to the mark
Perform the dilutions and validity checks as indicated by the work sheet.
Results:
Sodium chloride
Original
solution
Sample
mass:
Sample
volume:
Solution
concentration
Your Solution
readings
(ppm)
(target
0.254g)
R.I
100mL
Cond.
Standard
Sample
readings
R.I
Cond.
1000 Na
Solution
concentration
Serial
dilution
details
Volume
taken for
dilution
Final
diluted
volume
Dilution 1
10 mL
100 mL
100
Dilution 2
10 mL
100 mL
10
Dilution 3
10 mL
100 mL
1
Dilution 4
10 mL
100 mL
0.1
(ppm)
22
Hydrochloric Acid
Original
solution
Sample
mass:
Sample
volume:
Solution
concentration
Your Solution
readings
(molarity)
pH
0.1 M
n/a
n/a
0.1 M
Serial
dilution
details
Volume
taken
for
dilution
Final
diluted
volume
Solution
concentration
Dilution 1
10 mL
100 mL
0.01M
Dilution 2
10 mL
100 mL
0.001M
Dilution 3
10 mL
100 mL
0.0001M
Dilution 4
10 mL
100 mL
0.00001M
Cond.
Standard
Sample
readings
pH
Cond.
(molarity)
Questions:
1. What trends did you notice for your conductivity results.
2. What trends did you notice for your pH results. (hint: when an acidic solution is
diluted to one tenth its concentration, we expect to see a full pH unit increase)
23
Practical 6.1
Validation of sampling
Date Completed:
___________________ Teacher check _____________
Purpose
Analyst signature ___________
This practical task is designed to demonstrate whether the sampling procedure used
has produced a sample that truly reflects the composition of the bulk material. You
will create a bulk supply of material of known composition (~5% salt in sand) and you
will sample it for laboratory testing. You will measure its true salt content and
compare your answers to the expected values.
Results
Bulk
Supply
Mass of
sand (g)
Mass of salt
(g)
Sand +
salt total
(g)
% sand
% salt
Sampling details
Laboratory
samples
Mass of
empty
beaker
Mass of
beaker +
sample
Mass of
Mass of analytical
laboratory sample sample used in
test
1
1.
2.
3.
Analysis details for analytical samples
Mass of
empty filter
paper
Mass of
paper +
sand
Mass of
empty
evaporating
basin
Mass of basin Mass check on
+ salt residue cleaned out empty
basin
1
2
3
24
Analysis calculations
Mass of
sand
recovered
(a)
Mass of
salt
recovered
(b)
Recovered
sand + salt
total (a) +
(b)
Original mass
of analytical
sample used in
test
% sand
% salt
Recovered
Recovered
1
2
3
Questions:
1. Discuss any differences between the composition of the original bulk supply and
the test results for your recovered samples.
2. Comment on your recovery check. (the agreement between the mass of each of
your analytical samples and the recovered sand + salt masses after the analysis.
This tells how reliable your results might be.
3. Suggest how you could improve the method to achieve better % composition and
recovery check agreement.
25
Practical 6.3
Sampling Equipment
Date Completed:
___________________ Teacher check _____________
Purpose
Analyst signature ___________
This practical is designed to familiarise the technician with equipment available to
assist in the taking of a valid sample/
1. Record the sample identity which you have been allocated by the tide zone
from which it was obtained.
2. Using the riffles provided reduce the sample to approximately 100g and
record the analytical sample size in the table provided.
3. Repeat step 2 twice more
4. Select a nest of sieves and clean them thoroughly as demonstrated by the
teacher.
5. Record the aperture sizes and assemble them so that the aperture decreases
from biggest at the top to the smallest next to the catch pan.
6. Transfer one of the analytical samples to the top of the nest of sieves.
7. Shake the sieves (with the lid on) for 5 minutes
8. Using the A3 paper method demonstrated by the teacher, carefully capture
and record the mass of each fraction.
9. Repeat the procedure with the other samples.
Results:
Sample number
Sample mass
location on the beach from which the
sample was taken:
1
2
3
26
Sieve
size
Mass
sand
% sand in
fraction
Mass
sand
% sand in
fraction
Mass
sand
% sand in
fraction
Total
mass
Questions:
1. Did you recover 100% of the initial sample? If not where did you gain or lose sample in
the method?
2. Did you have good agreement between your triplicate samples?
27
Practical 7.1
pH Measurement
Date Completed:
___________________ Teacher check _____________
Purpose
Analyst signature _______
Indicator solutions, test papers and the pH meter are used to measure pH. Different
requirements for accuracy and speed will dictate which method is appropriate
The practical tasks provide experience with various detection methods for the
determination of pH.
Procedure:
Your teacher will demonstrate the use of each method. Whilst working with each
consider the accuracy and efficiency of the method.
Other
pH meter
Dipstick
Univerasal indicator
Phenolphthalein PP
Bromothymol blue BTB
Blue Litmus
Red Litmus
Results:
Original colour
Sample
28
Other
pH meter
Dipstick
Univerasal indicator
Phenolphthalein PP
Bromothymol blue BTB
Blue Litmus
Red Litmus
Questions:
Which method do you consider the most reliable?
Which household chemical was the most acidic?
Which household chemical was the most alkaline?
What information does litmus paper give?
29
Boiling Point
The boiling point (b.p.) of a liquid is defined as the temperature at which the
vapour pressure of the liquid is equal to the external pressure. Vapour pressure
tells you how easily a liquid evaporates — those which evaporate easily have the
lower boiling points. The external pressure most commonly used and reported is
atmospheric pressure and the resultant boiling temperature is most commonly
found in data books on boiling points.
The boiling point, like the melting point, of a compound is a useful means of
identification. Liquids are frequently characterised by distillation which is a
purification technique in which the impure liquid is heated to its boiling point, the hot
vapour passed through a cooling chamber called a condenser and the condensate
collected in a receiver. The boiling point is monitored continuously as the liquid is
being distilled and fractions collected over each new temperature range. These
fractions are suitable for other tests such as refractive index and density and these in
combination are quite effective for identification purposes. The standard apparatus
for distillation using ground glass jointed glassware is shown below.
Thermometer whose bulb is level with the
take-off point for hot vapour and far above
the boiling liquid surface
Water-filled condenser for
cooling distillate
Stillpot contains boiling liquid and
boiling chips and sits over a heat
source such as a mantle
Receiving flask for
condensate and receiver
adaptor with vacuum fitting
Apparatus for simple distillation and boiling point determination
30
Rules for Distillation
1. Always use boiling chips or anti-bumping granules (rough beads or chips of
marble, glass, tile or silicon carbide). When liquids are heated strongly in contact
with a smooth surface such as glass, the liquid does not always boil smoothly, but
rather it forms large (superheated) vapour bubbles on the hot surfaces of the
container. These bubbles erupt violently and can mechanically lift and agitate great
quantities of the remaining liquid and may actually cause the hot liquid to spurt out
of the top with the potential for further problems. The formation and effect of these
bubbles is called bumping. Boiling water in test tubes using a Bunsen is a classic
case and this should be demonstrated to you by your teacher. The water can spurt
suddenly over many metres and you can imagine the effect on an innocent victim, of
suddenly receiving such a projectile in the middle of their back. Many organic liquids
are flammable and toxic and so if these are allowed to bump, the consequences
can be extreme. The boiling chips promote the formation of a steady stream of small
bubbles.
2. Do not add boiling chips to hot liquids. If the liquid is already at its boiling point,
the chips will cause it all to boil at once and again the liquid may lift itself out of the
container. Allow the liquid to cool, add the chips and reheat.
3. Always turn the water to the condenser on before the heating device.
Otherwise, solvent vapours may escape, creating a fire and health hazard.
4. Boiling chips cannot be trusted to work a second time. Add fresh ones
always!
31
To determine the boiling point of a liquid by simple distillation
Date Completed:
___________________ Teacher check _____________
Analyst signature _______
Safety Aspects
1. Handling flammable liquids
2. Bumping
3. Cooling water essential for hot vapour condensation.
4. Boiling dry
Techniques involved
1. Use of Quickfit equipment
2. Use of heating mantles
Procedure
Practice Distillation
1. Pour 60 ml of the practice liquid sample, into a clean, dry 100mL Quickfit flask
and add 2 anti-bumping granules
WATER IS TO BE AVOIDED AT ALL COSTS AS A POSSIBLE CONTAMINANT DURING
DISTILLATION, BECAUSE OF ITS TENDENCY TO CO-DISTIL WITH YOUR SAMPLE AND THUS
REMAIN A SERIOUS IMPURITY
2. Use the demonstration apparatus on display to assemble your distillation
setup.
Connect a Quickfit distillation head to a Quickfit 100ml round-bottomed flask,
a 110oC thermometer, a Quickfit condenser, and a Quickfit receiver adaptor
which empties into a 100mL measuring cylinder or appropriate sample tube.
Use a heating mantle as the heat source and clamp both the distillation head
and the condenser securely.
3. Connect the condenser up to a water tap, with the water entering at it’s lower
end, this results in the most efficient cooling action on the hot vapours
entering the condenser. Turn the water on.
4. You MUST ask the teacher to check you set up.
5. Turn the heating mantle up to about 80% of maximum. Note the temperature
at which the vapour first enters the condenser, and thence after every 5ml
collected. You will need to control the heating rate to give a distillation rate of
1-2 mL per minute.
6. Turn off the heater when about 10mL of liquid is left in the flask. Do not allow
the flask to boil dry as it may crack and the leakage will catch fire. Leave the
water running through the condenser for a few until the equipment cools
32
somewhat. Measure and record the boiling range and R.I for the initial, middle
and final fractions collected.
7. Disassemble the equipment, clean and dry each piece and put everything
away. Often with low boiling samples, draining and storage will be all that is
needed as any residual liquid will evaporate. Any water used in cleaning may
not evaporate and hence will contaminate your next sample.
8. Validate your results for the liquid using the list on the laboratory notice board.
9. You will be issued with two unknown liquids for which you are to determine
the boiling point and for which you are to assess purity and identify by
measurement of refractive index and comparison of your experimental data to
published tables of B.Pt and R.I.
10. Repeat steps 1 to 8 using the appropriate condenser as directed by the
teacher.
Boiling Point Results Table
Volume
of
distillate
(mL)
Temp
Reading
(oC)
R.I.
Practice Sample
Possibilities
1 - Propanol
fraction 1
fraction 2
fraction 3
Unknown code No....
Volume
of
distillate
(mL)
Temp
Reading
(oC)
R.I.
Possibilities
fraction 1
fraction 2
fraction 3
33
Questions.
1. Why is it necessary to very lightly grease Quickfit joints?
2. Why is the thermometer bulb not immersed in the liquid to determine the
boiling range?
3. Why is a heating mantle used in this determination rater than a Bunsen
burner?
4. Why must the water to the condenser be running before the heating mantle is
switched on?
5. What effect does too fast a heating rate have on the boiling range?
6. Why is the distillation stopped before all the sample has been distilled?
7. Report the identity of all you samples and any uncertainty you may have
34
Preparation of Ethanol
Ethanol (C2H5OH) is a very important member of the alkanol family. It is used as a
solvent for perfumes, flavourings and varnishes, as an ingredient of many alcoholic
beverages and as a raw material in the manufacture of numerous products.
Ethanol can be produced by the fermentation of sugar using yeast. The fermentation
process also produces a gas. This gas can be identified by the use of limewater. The
final product is purified using distillation.
Preparation and Purification of Ethanol
Date Completed:
Purpose
___________________ Teacher check _____________
Analyst signature _______
1. To prepare ethanol by the process of fermentation
2. To identify the gas given off during fermentation
3. To purify the fermentation mixture to recover the ethanol
Procedure
1.
1.
2.
3.
Preparation of ethanol and identification of the gas produced.
Set up the apparatus as shown by your teacher
Draw and label the set-up
Place about 10 g of glucose, C6H12O6, 60 mL of purified water and 7 g yeast in
the flask.
4. Stopper flask and then agitate the mixture gently.
5. Position the delivery tube a little under the surface of the limewater and allow the
mixture to ferment for one week in a warm place
Results
Diagram
35
2. Purification of Fermentation Mixture.
Procedure
1. Observe the demonstration by your teacher of the flammability of ethanol.
2. Note any changes to the fermentation flask and the gas collection tube
3. Test the fermentation mixture for flammability by dipping a piece of string into the
mixture, removing and then attempting to light the string.
4. Filter the contents of the flask through a small wad of cottonwool.
5. Transfer the filtrate to a small round-bottom flask
6. Set up the apparatus for a simple distillation (don’t forget the boiling chips)
7. Collect the fraction of distillate with a boiling point of below 85 oC.
8. Test the distillate for flammability as in step 1.
Results
Observation of flask after
fermentation process
Observation of gas collection flask
after fermentation process
Observation of flammability of
initial fermentation mixture
Observation of flammability of
ethanol
Observation of flammability of
distillate
Apparent boiling point of distillate
Questions
1) Identify the gas produced during the fermentation of glucose
2) Write a balanced equation for the fermentation reaction
36
3) Write a balanced equation to represent the complete combustion of ethanol in
air
4) Most table wines contain a maximum of about 12% ethanol. Suggest why this
upper limit occurs in the fermentation process. How could a sherry containing
30% ethanol be produced?
37
Other Distillation Methods
Separation of a mixture by fractional distillation
Simple distillation is useful to separate liquids that have a boiling point difference of
greater than 700C. It does not satisfactorily separate liquids that have close boiling
points, for example a mixture of water and ethanol. Here the water has a BPt of 100o
while ethanol boils at 78oC ie simple distillation is not able to isolate each of the
fractions.
Fractional distillation is a useful technique for separation of soluble substances with
boiling points that are close, for example water and ethanol. The method utilises a
fractionating column which provides a large surface area for the separation to occur.
When conducting your distillation take particular note of the temperature differences
on the two thermometers.
38
Practical Observation of Fractional Distillation
Date Completed:
___________________ Teacher check _____________
Purpose
Analyst signature __________
To observe a mixture being separated by fractional distillation, identify the main
pieces of equipment and note safety issues.
Procedure
1) Draw a diagram of the fractional distillation apparatus, identifying the glassware
components.
2) Complete the table with your observations
Identity of mixture
Temperature of bottom thermometer
Temperature of top thermometer
Boiling point of first component
How could you identify the component
39
Questions
1. The rate of heating must be controlled in order to keep the maximum possible
temperature gradient in the column.
Too low means ………………………………………………………………………
…………………………………………………………………………………………
Too high means …………………………………………………………………….
…………………………………………………………………………………………
2. Identify safety issues that can arise during a fractional distillation
3. Identify where this process is applicable in the real world.
40
Steam Distillation
Steam distillation provides a way of separating and purifying organic compounds.
The process consists of passing steam into the organic mixture and water. Many
organic compounds are volatile and this property enables the compound to distil with
the steam.
Essentially the steam is acting as a:


Heat source, improving vapour generation
Carrier gas to sweep the vapours away from the stillpot and into the
condenser.
Steam distillation takes place normally below the boiling point of water and generally
well below the boiling point of the compound. This low temperature distillation
prevents the decomposition of any compound which could occur if it was distilled at
atmospheric pressure.
Applications of steam distillation
Steam distillation is very useful in separating or isolating volatile organic compounds.
a) From non-volatile tarry substances which are formed as by-products in many
reactions
b) From aqueous mixtures containing dissolved inorganic salts
c) In those cases where other means of separation might lead to difficulties (eg
formation of emulsions)
d) From compounds which are not appreciable volatile in steam
e) From certain by-products which are steam volatile
The general process





A stillpot contains the mixture to be steam distilled
The stillpot is fitted with a splash-head (or similar) which acts to prevent the
accidental carry-over by splashing of liquid from the stillpot into the
condenser.
The stillpot receives externally generated steam, but is also heated to prevent
too much water build up
The vapours pass into the condenser, are cooled and the organic compounds
and water are collected in a receiver.
The method of isolation of the organic compound from the distillate depends
on its water solubility
41
Practical Observation of Steam Distillation
Date Completed:
___________________ Teacher check _____________
Purpose
Analyst signature __________
Procedure and Results
1) Draw a diagram of the steam distillation apparatus, identifying the main
components.
2) Complete the table with your observations and notes
Identity of mixture
Compounds in collection flask
Appearance of collection flask
Suggestions for separation of collected
material
42
Questions
1. What is the purpose of the safety tube attached to the steam generator?
2. What would be the effect of removing the Bunsen flask before you disconnected
the receiving flask?
3. What are the major safety concerns with the operation of this type of distillation?
4. How could you determine which is the organic layer in a separatory funnel?
5. Explain how the splash head works
43
Vacuum Distillation
Many substances cannot be safely distilled at atmospheric pressures because the
temperatures needed are sufficient to cause bond breaking to occur and the material
to decompose. Steam distillation may not be an alternative if compounds are water
sensitive. Vacuum distillation works by lowering the pressure above the distillation
mixture thereby lowering the boiling point of the material of interest.
In practice the procedure requires a number of modifications to a simple distillation






A vacuum pump to reduce the pressure
A sealed distillation system to contain the sample at reduced pressure
A replacement for boiling chips which fail under vacuum
Good quality glassware to handle the implosive stresses
A vacuum gauge to monitor pressure to ensure B.Pt is reported at a fixed
pressure and that vacuum failure or build-up can be anticipated
A rapid failsafe shut down procedure in the event of an emergency.
Practical Observation of Vacuum Distillation
Date Completed:
___________________ Teacher check _____________
Purpose
Analyst signature __________
Procedure and Results
1) Draw a diagram of the vacuum distillation apparatus, identifying the main
components.
44
2) Complete the table with your observations and notes
Identity of the impure compound
Literature value for boiling point
Observed boiling point under vacuum
Questions
1. What is the reason for the inclusion of the ―flashback‖ bottle in the system?
2. Why is a thick walled capillary tube inserted into the distillation flask?
3. Why is it preferable for high-boiling organic liquids to be distilled at reduced
pressure?
45
Practical 7.3 Mixed Melting Point
Date Completed:
Purpose
___________________ Teacher check _____________
Analyst signature __________
The principle of mixed melting point will be investigated to establish the identity of an
unknown substance.
Procedure
1.
Grind a small amount of benzoic acid or on a small watch-glass with a firepolished glass rod.
2.
Using a calibrated Kohfler hotbench or a capillary melting point apparatus
machine determine the melting point of the benzoic acid. Record your result
3.
Repeat the above procedure to determine the melting range of a pure sample of
(beta)-naphthol and record your result.
4.
Practise the technique of mixed melting point, using a 1:1 (approximately) mix
of benzoic acid and -naphthol. Grind the mixture finely and determine its
melting point. Record the melting range.
5.
You will be issued with organic solid unknowns. Repeat the above procedure to
determine each melting range. Consult the laboratory list for possible identities.
6.
Confirm your identification by carrying out a mixed melting point of your
unknown with each of the available standard compounds which melt within 10C
of this melting point. Record all your results in your logbook.
46
Results:
Sample
Temperature
Literature value
Sample 1:
benzoic acid
Sample 2:
2 – naphthol
Mixture of samples 1 & 2:
Observation
Sample 3:
Unknown Code
Possibilities are:
Mix of Sample 3 + first
suspected compound
conclusion
Mix of Sample 3 + second
suspected compound
conclusion
Unknown code …
was found to be
Sample 4:
Unknown Code
Possibilities are:
Mix of Sample 4 + first
suspected compound
conclusion
Mix of Sample 4 + second
suspected compound
conclusion
Unknown code …
was found to be
Questions
1. If a dirty mortar was used to prepare a sample for melting point, how would the
actual melting point compare to the expected value for the pure compound?
47
2.
What effect does too fast a heating rate have on the melting point?
3.
What disadvantage does too slow a heating rate have?
4.
Explain the technique of mixed melting point and why it always works.
5.
Outline safety issues with the practical and note how these can be minimised.
48
Practical 7.5 Refractive Index
Date Completed:
___________________ Teacher check _____________
Purpose
Analyst signature __________
To examine the ways refractive index is useful for:


identification of materials
quantification of composition.
Procedure and Results
A. Identification of unknown
1. Determine the refractive index of the unknown sample using the technique shown
in the calibration of a refractometer practical.
2. Make all necessary corrections for temperature and machine as shown
previously.
Substance
Initial
RI reading
Temperature
of sample
Temperature
Corr. factor
Termperature
Corrected RI
Instrument
correction
(using water
@ 20oC
value of
1.333
Final
Corrected
value RI
Water
Unknown
49
B. Quantification of composition of known analyte
Procedure
1.
2.
3.
4.
Measure the refractive index of each of the standard solutions
Measure the refractive index of the unknown solutions
Prepare a graph of concentration of analyte vs refractive index for standards
Determine the concentration of the analyte in the unknown solutions
Results
Identity of analyte
Concentration
Refractive Index
15%
30%
45%
Unknown 1
Unknown 2
Concentration Unknown 1
Concentration Unknown 2
Questions
1. Why was it important to record the temperature of the solutions in Part A but not
in Part B?
2. Why do we need a set of standard solutions in order to determine the
concentration of the analyte in the unknowns.
50