ph (potential of hydrogen) small

8/7/2019 pH (potential of Hydrogen) small

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Measures if the solution is anacidic(base) or alkaline (basic)


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No questions aloud!!! Ok?


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The process of oxidation involves losingelectrons while reduction involves

gaining electrons.

ORP = millivolts (mV)



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a very dilute solution will take time

to accumulate a measurablecharge.

ORP sensor



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Water treatment

Metal Finishing

Ozone treatment Bleach production

Poultry processing

Fruit and vegetable washing

Pulp bleaching

Chlorine addition



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Anions Cations

Radicals or Radicals ions

Measuring electrode

Reference electrode

Temperature sensor


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It is also called glass electrode

Silver is the best electrical conductor



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it provides a constant potentialregardless of the composition of the

solution it is placed in. Should be stable and constant



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Ideally, no reaction

between the reference

electrolyte and themeasuring solution

should occur.



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Glass Stem

Reference Wire

Internal Buffer Solution

Glass Membrane

The Glass Electrode

N ti l d!!! Ok?


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How Glass Electrodes Work

H+H+ H+

H+

H+H+ H+

H+

When the glass is put into solution it

undergoes a chemical reaction which formsa leached layer on the inside and theoutside of the glass. The Hydrogen Ionscause a charge to be produced on theinside and outside on the glass. As the pHchanges so does the charge differentialbetween the inside and outside of theglass. This charge differential is aPOTENTIAL difference which is read asmillivolts. Thus, the change in HydrogenIon concentration will be measured as amillivoltage. Since the internal fill solutionis pH 7, when a process is pH 7 the outputfrom the electrode is ZERO millivoltsbecause the charge on the inside is thesame as on the outside and there is nopotential difference.


N ti l d!!! Ok?


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Styles of Glass Electrodes

The glass membrane itself is not limited to any configurationor shape; its only requirement is contact with solution.Therefore, different styles of glass electrodes have evolvedto maximize pH sensing ability and extend longevity in some

of the more difficult applications.



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Alloy Steel

Stainless steel



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Cell constant (of a conductivity cell)

Defined as:

kcell = kR

where R is the measured resistance ofthe cell and k is the conductivity

(formerly called the specificconductance).




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is the amount of oxygen that is dissolvedin water and is essential to healthy

streams and lakes. The dissolved oxygenlevel can be an indication of howpolluted the water Generally, a higherdissolved oxygen level indicates better

water quality.




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Much of the dissolved oxygen in watercomes from oxygen in the air that has

dissolved in the water. Some of thedissolved oxygen in the water is a result ofphotosynthesis of aquatic plants. Otherfactors also affect DO levels such as on

sunny days high DO levels occur in areas ofdense algae or plants due tophotosynthesis. Stream turbulence may alsoincrease DO levels because air is trapped

under rapidly moving water and theoxygen from the air will dissolve in thewater.



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it is the process of attraction of atoms ormolecules from an adjacent gas or liquid

to an exposed solid surface.




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(1) Solvent reservoirs, (2) Solvent degasser, (3) Gradient valve, (4)Mixing vessel for delivery of the mobile phase, (5) High-pressure pump,(6) Switching valve in "inject position", (6') Switching valve in "loadposition", (7) Sample injection loop, (8) Pre-column (guard column), (9)Analytical column, (10) Detector (i.e. IR, UV), (11) Data acquisition, (12)

Waste or fraction collector.




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The sample to be analyzed is introduced in small volume tothe stream of mobile phase. The analyte's motion throughthe column is slowed by specific chemical or physicalinteractions with the stationary phase as it traverses the

length of the column.

How much the analyte is slowed depends on the nature ofthe analyte and on the compositions of the stationary andmobile phases.

The time at which a specific analyte elutes is called theretention time; the retention time under particularconditions is considered a reasonably unique identifyingcharacteristic of a given analyte.

The use of smaller particle size column packing (whichcreates higher backpressure) increases the linear velocitygiving the components less time to diffuse within thecolumn, leading to improved resolution in the resultingchromatogram..


ph (potential of hydrogen) small

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