Basic Analytical
Techniques, Calorimeter,
and Conductivity Meter
Santosh Vijapur
ABC’s of Electrochemistry
01/12/2012
Outline
• Calorimeter
• Conductivity meter
• pH meter
• Analytical balance
• Glassware cleaning
• Micro-pipette
Center for Electrochemical Engineering Research, Ohio University
2
Calorimeter
Definition
• “Calorimetry is the science of measuring
quantities of heat and instruments used for such
measurements are known as calorimeters.”
http://itl.chem.ufl.edu/2045/lectures/lec_9.html
http://www.dartmouth.edu/~chemlab/techniques/calorimeter.html
http://www.physicsclassroom.com/class/thermalP/u18l2c.cfm
Center for Electrochemical Engineering Research, Ohio University
3
Calorimeter
History
• French scientist and statesman, Berthelot (1827-1907), was
the first to develop principles of modern calorimetric
methods using oxygen under pressure to affect combustion.
• Calorimeter bomb he developed was lined with platinum to
withstand the gases produced during combustion.
• It was modified in 1892 by Mahler by depositing porcelain
enamel on the steel, to replace the expensive platinum
lining.
• Further modifications were made by Fischer, Hempel and
others between 1844-1907.
http://www.parrinst.com/wp-content/uploads/downloads/2011/07/TN104_Parr_Calorimeter-ApplicationsTech-Note.pdf
Center for Electrochemical Engineering Research, Ohio University
4
Calorimeter
Types of calorimeters
• Adiabatic calorimeters: Used to investigate runaway
reactions.
• Reaction calorimeters: Measures amount of energy released
or absorbed in a chemical reaction.
• Constant pressure calorimeters: Measures changes in
enthalpy occurring in solution at constant atmospheric
pressure.
• Differential scanning calorimeters: Measures the difference
in the amount of heat required to increase the temperature of a
sample and reference as a function of temperature.
• Bomb calorimeters: Measures the heat of combustion of a
particular reaction.
Center for Electrochemical Engineering Research, Ohio University
5
Calorimeter: Basic operating principle
Coffee Cup Calorimeter – constant pressure
Q  m C p T
Constant volume calorimetry
measures the change in Internal
energy,
whereas
constant
pressure calorimetry directly
measures enthalpy change
during the reaction.
http://itl.chem.ufl.edu/2045/lectures/lec_9.html
Center for Electrochemical Engineering Research, Ohio University
6
Bomb calorimeters
• “Standard instruments for measuring calorific values of
solid and liquid combustible samples”
• The calorific values denotes the overall heat liberated by
combustion of carbon and hydrogen along with oxidation of
elements like sulfur present in the sample.
http://itl.chem.ufl.edu/2045/lectures/lec_9.html
Center for Electrochemical Engineering Research, Ohio University
7
Bomb calorimeter
Bomb Calorimeter – constant volume
• Both instruments work on a
similar principle.
• Heat evolved during a
chemical reaction changes
the temperature of a
substance (water bath) with a
known heat capacity.
http://itl.chem.ufl.edu/2045/lectures/lec_9.html
• This measurement of
difference in temperature
facilitates the determination of
the heat crossing the system
boundary.
Center for Electrochemical Engineering Research, Ohio University
8
Bomb calorimeter
Applications of Bomb calorimeters
• Solid and Liquid Fuel Testing
• Waste and Refuse Disposal
• Food and Metabolic Studies
• Propellant and Explosive Testing
• Fundamental Thermodynamic Studies
http://www.parrinst.com/wp-content/uploads/downloads/2011/07/TN104_Parr_Calorimeter-ApplicationsTech-Note.pdf
Center for Electrochemical Engineering Research, Ohio University
9
Conductivity meter
Description
• Two electrodes with an applied
AC voltage are placed in the
solution.
• A current is generated depending
upon the conductive nature of the
solution.
• The meter reads this current and
displays in terms of conductivity.
http://www-ec.njit.edu/~grow/sensors/CONPROB.htm
http://www.hannainst.com/usa/knowledge.cfm#whatisec
Center for Electrochemical Engineering Research, Ohio University
10
Conductivity meter
Standardization
• Select calibration mode.
• One point calibration
• Freeze reading
• Repeat using conductivity standard.
• Rinse the sensor.
http://us.mt.com/global/en/home/supportive_content/product_documentation/operating_instructions/Operating_Instruction_MC2
26.rxHgAwXLlLnPBMDSzq--.MediaFileComponent.html/Operating_Instruction_mc226.pdf
Center for Electrochemical Engineering Research, Ohio University
11
Conductivity meter
How to…
• Select measurement mode.
• Measure sample
• Freeze reading
• Rinse sensor
http://us.mt.com/global/en/home/supportive_content/product_documentation/operating_instructions/Operating_Instruction_MC2
26.rxHgAwXLlLnPBMDSzq--.MediaFileComponent.html/Operating_Instruction_mc226.pdf
Center for Electrochemical Engineering Research, Ohio University
12
Conductivity meter
Operating tips
• The solution to be measured should be above the cell
chamber slot.
• The cell chamber should be free of bubbles.
• Immerse the sensor at an angle and then raise to the
vertical position in order to reduce air bubbles.
• Rinse sensor with distilled water between measurements,
and after use.
• For greatest accuracy, standards and samples should be at
the same temperature and should be close in value.
http://us.mt.com/global/en/home/supportive_content/product_documentation/operating_instructions/Operating_Instruction_MC2
26.rxHgAwXLlLnPBMDSzq--.MediaFileComponent.html/Operating_Instruction_mc226.pdf
Center for Electrochemical Engineering Research, Ohio University
13
Conductivity meter
Prevention & Care
• Rinse with DI water.
• Wipe the meter with a damp cloth.
• Clean any spillages.
http://us.mt.com/global/en/home/supportive_content/product_documentation/operating_instructions/Operating_Instruction_MC2
26.rxHgAwXLlLnPBMDSzq--.MediaFileComponent.html/Operating_Instruction_mc226.pdf
Center for Electrochemical Engineering Research, Ohio University
14
pH meter
Description
• pH-sensing glass bulb is sensitive
to hydrogen ions.
• A potential is developed at the
glass membrane and is related to
the pH of the solution.
• A reference electrode is paired to
complete the circuit and provides
a stable reference point.
http://www.denverinstrument.com/denverusa/media
/pdf/OpManUBLongRevA.pdf
• These two electrodes are joined
to create a combination electrode.
• The combination glass electrode
is connected to the pH meter
Center for Electrochemical Engineering Research, Ohio University
15
pH meter
Standardization
• Standardize daily, or more often, for accurate results.
• Clear existing buffers when doing a new standardization, by
pressing setup and enter buttons.
• Immerse the electrode in three different buffers to standardize
the meter.
• Immerse the electrode in a buffer, stir gently and then press
standardize.
• When reading is stable or when you press enter, the buffer is
entered.
• Repeat for other buffers.
http://www.denverinstrument.com/denverusa/media/pdf/OpManUBLongRevA.pdf
http://www.dartmouth.edu/~chemlab/techniques/phD.html
Center for Electrochemical Engineering Research, Ohio University
16
pH meter
Prevention & Care
• Before using your pH electrode, or whenever the electrode
is dry, soak over-night in an Electrode Storage or KCI
solution.
• Rinse electrodes with DI water or the solution to be
measured and blot-dry (do not wipe) between each
measurement.
• Store pH electrodes in an Electrode Storage or KCI solution.
http://www.denverinstrument.com/denverusa/media/pdf/OpManUBLongRevA.pdf
Center for Electrochemical Engineering Research, Ohio University
17
Weighing balance
How to…
• Place weighing dish on the balance pan.
• Close the doors. Wait for the stability indicator to appear on
the display, indicating that the weight is stable.
• Press the tare button to cancel out the weight of the
weighing dish.
• Add the desired substance into the dish carefully up to the
desired mass.
• Close the doors and wait for the stability indicator to appear.
• Weigh the dish 3 times to get an average weight of the
substance.
http://www.dartmouth.edu/~chemlab/techniques/a_balance.html
Center for Electrochemical Engineering Research, Ohio University
18
Weighing balance
Prevention & Care
• Do not lift the weighing dish by bare hands as the finger
prints could add to the mass.
• Do not lean on the bench while weighing.
• It is advisable to record the mass of the weighing dish just in
case you need it.
• Also, it is necessary to check the screw levels of the
weighing balance.
• Use brush to clean any spills in chamber and around the
balance.
• Discard unnecessary dish, kimwipes, etc. into the waste
can.
http://www.dartmouth.edu/~chemlab/techniques/a_balance.html
Center for Electrochemical Engineering Research, Ohio University
19
Weighing balance
Calibration
• Calibration necessary:
 before the first use.
 at regular intervals.
 After location change.
• Fully automatic calibration in some balances (time interval,
temperature deviation, after turning on the balance).
http://us.mt.com/global/en/home/supportive_content/product_documentation/operating_instructions/Operating_Instructions_MS-S_MSL_EN.rxHgAwXLlLnPBMDSzq--.ExternalFileComponent.html/Operating_Instructions_MS-S_MS-L_%28OP-EN%29.pdf
Center for Electrochemical Engineering Research, Ohio University
20
Weighing balance
External Calibration
http://us.mt.com/global/en/home/supportive_content/product_documentation/operating_instructions/Operating_Instructions_MS-S_MSL_EN.rxHgAwXLlLnPBMDSzq--.ExternalFileComponent.html/Operating_Instructions_MS-S_MS-L_%28OP-EN%29.pdf
Center for Electrochemical Engineering Research, Ohio University
21
Glassware cleaning
• Clean glassware is an important criteria in a Good
Laboratory Practice.
• PPE must be used when cleaning glassware's.
• Clean glasswares immediately after use.
• Soap/detergent can be used to clean glasswares and
should be scrubbed with a brush.
• Precipitates or organic matter that make the glasswares
unduly cloudy can be cleaned using concentrated acids or
bases. Special precaution should be taken and proper
procedure should be followed in such case.
http://catalog2.corning.com/Lifesciences/media/pdf/CLS_AN_112_CleaningGlassware.pdf
Center for Electrochemical Engineering Research, Ohio University
22
Glassware cleaning
• Glasswares should be properly rinsed with running tap
water.
• Acetone or similar solvents can be used to remove grease.
Soaking can also be implemented in some cases.
• The glassware’s should be air dried by placing them on the
wooden pegs with their mouth downward.
http://catalog2.corning.com/Lifesciences/media/pdf/CLS_AN_112_CleaningGlassware.pdf
Center for Electrochemical Engineering Research, Ohio University
23
Micro-pipette
Description
Most of the micro-pipettes have
color coded volume display
http://www.denvillescientific.com/Products.php?Cat=109
Center for Electrochemical Engineering Research, Ohio University
24
Micro-pipette
How to…
• Insert the shaft into the tip and press down firmly.
• Do not touch the tip with bare hands to avoid contamination.
• The tip box should be closed when not in use to prevent
contamination.
• Micro-pipette should be immersed to the minimum
necessary depth into the liquid.
• Hold the micro-pipette in vertical position.
• Pre-rinse the tip with the liquid to be pipetted.
• Change the tip while using different liquid, or when volume
setting is changed.
http://faculty.buffalostate.edu/wadswogj/courses/BIO211%20Page/Resources/micropipetting%20lab.pdf
http://www.denvillescientific.com/Products.php?Cat=109
Center for Electrochemical Engineering Research, Ohio University
25
Micro-pipette
Prevention & Care
• Use smooth motion.
• The liquid should never enter the shaft of the micro-pipette
(Do not turn the pipette upside down or place it sideward's
when liquid inside the tip).
• Do not overshoot the limits.
• Do not pipette liquids with temperature beyond
recommended point.
• After pipetting acids or corrosive substances, disassemble
the shaft, then clean the piston and seal with DI water.
http://faculty.buffalostate.edu/wadswogj/courses/BIO211%20Page/Resources/micropipetting%20lab.pdf
http://www.denvillescientific.com/Products.php?Cat=109
Center for Electrochemical Engineering Research, Ohio University
26
Micro-pipette
Calibration
• Calibration necessary:
 When a part is replaced.
 At periodic intervals, depending on the usage.
• Types: Gravimetric method, Photometric method, Titrimetric
method, and Isotopic method.
• Gravimetric and Photometric method are common methods.
http://www.biotekcalibrations.com/images/pipette-standards-handbook.pdf
Center for Electrochemical Engineering Research, Ohio University
27
Micro-pipette
Calibration: Gravimetric method
• Gravimetric method requires a controlled environment, a
high precision balance, a skilled technician, distilled water,
and understanding of statistics.
• It works on the principle that, given a certain mass of water
with a known specific gravity; its volume can then be
predicted.
• The accuracy and precision of the pipette can then be
assessed by statistical approach.
http://www.biotekcalibrations.com/images/pipette-standards-handbook.pdf
Center for Electrochemical Engineering Research, Ohio University
28
Micro-pipette
Calibration: Photometric method
• Photometric method involves the analysis of volumes of
diluted dye in a cell of known path length.
• It works on the principle of Beer-Lambert Law
• “If a beam of monochromatic radiation passes through
homogeneous solutions of equal path length, the
absorbance measured is proportional to the dye
concentration.”
• An unknown dye volume can be pipetted into a known
diluent volume. The concentration of dye can be measured
photometrically, and the volume can be calculated.
http://www.biotekcalibrations.com/images/pipette-standards-handbook.pdf
Center for Electrochemical Engineering Research, Ohio University
29
Micro-pipette
Adjustment
• The adjustment is performed at the lower volume.
• The pipette service tool is placed into the openings of the
calibration nut.
• Turn the tool clockwise to increase the volume or counter
clockwise to decrease the volume.
• Recheck the calibration.
http://www.pipette.com/Support/GuideToPipetting.pdf
Center for Electrochemical Engineering Research, Ohio University
30
For more information,
please contact:
[email protected]
www.ohio.edu/ceer