Basic Analytical Techniques, Calorimeter, and Conductivity ... · Calorimeter • Adiabatic...

Basic Analytical

Techniques, Calorimeter,

and Conductivity Meter

Santosh Vijapur

ABC’s of Electrochemistry

01/12/2012

2 Center for Electrochemical Engineering Research, Ohio University

Outline

• Calorimeter

• Conductivity meter

• pH meter

• Analytical balance

• Glassware cleaning

• Micro-pipette


Calorimeter

• “Calorimetry is the science of measuring

quantities of heat and instruments used for such

measurements are known as calorimeters.”

Definition

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


Calorimeter

• 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.

History

http://www.parrinst.com/wp-content/uploads/downloads/2011/07/TN104_Parr_Calorimeter-Applications-

Tech-Note.pdf


Calorimeter

• 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.

Types of calorimeters


Calorimeter: Basic operating principle


pQ m C T

Coffee Cup Calorimeter – constant pressure

Constant volume calorimetry

measures the change in Internal

energy, whereas constant

pressure calorimetry directly

measures enthalpy change

during the reaction.


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.



Bomb calorimeter


• 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.

• This measurement of

difference in temperature

facilitates the determination of

the heat crossing the system

boundary.

Bomb Calorimeter – constant volume


Bomb calorimeter

• Solid and Liquid Fuel Testing

• Waste and Refuse Disposal

• Food and Metabolic Studies

• Propellant and Explosive Testing

• Fundamental Thermodynamic Studies

Applications of Bomb calorimeters

http://www.parrinst.com/wp-content/uploads/downloads/2011/07/TN104_Parr_Calorimeter-Applications-

Tech-Note.pdf


Conductivity meter

http://www-ec.njit.edu/~grow/sensors/CONPROB.htm

http://www.hannainst.com/usa/knowledge.cfm#whatisec

• 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.

Description


Conductivity meter

• Select calibration mode.

• One point calibration

• Freeze reading

• Repeat using conductivity standard.

• Rinse the sensor.

Standardization

http://us.mt.com/global/en/home/supportive_content/product_documentation/operating_instructions/Operating_Instruction_MC2

26.rxHgAwXLlLnPBMDSzq--.MediaFileComponent.html/Operating_Instruction_mc226.pdf


Conductivity meter

• Select measurement mode.

• Measure sample

• Freeze reading

• Rinse sensor

How to…




Conductivity meter

• 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.

Operating tips




Conductivity meter

• Rinse with DI water.

• Wipe the meter with a damp cloth.

• Clean any spillages.

Prevention & Care




pH meter

http://www.denverinstrument.com/denverusa/media

/pdf/OpManUBLongRevA.pdf

• 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.

• These two electrodes are joined

to create a combination electrode.

• The combination glass electrode

is connected to the pH meter

Description


pH meter

• 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.

Standardization

http://www.denverinstrument.com/denverusa/media/pdf/OpManUBLongRevA.pdf

http://www.dartmouth.edu/~chemlab/techniques/phD.html


pH meter

• 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.

Prevention & Care

http://www.denverinstrument.com/denverusa/media/pdf/OpManUBLongRevA.pdf


Weighing balance

• 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.

How to…

http://www.dartmouth.edu/~chemlab/techniques/a_balance.html


Weighing balance

• 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.

Prevention & Care

http://www.dartmouth.edu/~chemlab/techniques/a_balance.html


Weighing balance

• 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).

Calibration

http://us.mt.com/global/en/home/supportive_content/product_documentation/operating_instructions/Operating_Instructions_MS-S_MS-

L_EN.rxHgAwXLlLnPBMDSzq--.ExternalFileComponent.html/Operating_Instructions_MS-S_MS-L_%28OP-EN%29.pdf


Weighing balance

http://us.mt.com/global/en/home/supportive_content/product_documentation/operating_instructions/Operating_Instructions_MS-S_MS-

L_EN.rxHgAwXLlLnPBMDSzq--.ExternalFileComponent.html/Operating_Instructions_MS-S_MS-L_%28OP-EN%29.pdf

External Calibration


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


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


Micro-pipette

http://www.denvillescientific.com/Products.php?Cat=109

Most of the micro-pipettes have

color coded volume display

Description


Micro-pipette

• 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.

How to…

http://faculty.buffalostate.edu/wadswogj/courses/BIO211%20Page/Resources/micropipetting%20lab.pdf



Micro-pipette

• 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.

Prevention & Care

http://faculty.buffalostate.edu/wadswogj/courses/BIO211%20Page/Resources/micropipetting%20lab.pdf



Micro-pipette

• 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.

Calibration

http://www.biotekcalibrations.com/images/pipette-standards-handbook.pdf


Micro-pipette

• 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.

Calibration: Gravimetric method



Micro-pipette

• 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.

Calibration: Photometric method



Micro-pipette

• 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.

Adjustment

http://www.pipette.com/Support/GuideToPipetting.pdf

www.ohio.edu/ceer

For more information,

please contact:

[email protected]

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