The pH-value of a liquid can be calculated using the potentiometric measurement principle. This video shows what it is about and how this measuring principle works. www.products.en...
Mansi Gupta where ‘re you from, Mansi. I ‘m Charlie come from Viet An Enviro, representative of EH in Vietnam. Welcome to support you about EH products
Sir thank you very much for this video.We are using ph analyzer in a power plant in Saudi arabia.All of made of Endress Hauser......Sir very grate invention.I am proud on you.
Great video, but didn't quite understand the animation of the junction. If the junction should "protect the reference system from the medium measures" then I guessed that it would chemically isolate the reference system but the animation was to the country. Until I found this explanation, which you might also find helpful: "The reference junction, also known as a diaphragm, creates electrical contact between the reference system and the solution. Much like the reference electrolyte, the reference junction must possess certain qualities. Diffusion voltages at the junction are a common measurement error, so the junction plays a major role in the precision of measurements. To keep these disruptive potentials small, the junction must guarantee a relatively large and consistent outflow of reference electrolyte. However, the junction must only be slightly permeable to prevent electrolyte from escaping too quickly, which is especially important with electrodes utilizing liquid electrolyte. Different junction types have different outflow rates of electrolyte. In addition to the permeability of the junction, its electrical resistance should be as low as possible and it must be chemically inert."
Good observation, you are absolutely correct. The junction does not isolate the reference cell completely from the other medium, but it will limit the leaking of electrolyte into the medium. This is necessary to ensure an electrical connection. The sensor shown in this video has a PTFE ring-diaphragm, but for different applications other options are also available. Other options are for example 1 or 3 ceramic junctions witch are smaller and have a smaller pore size, this will have a lower outflow of KCl. Or for some applications an open junction is used, this will be basically just a hole on the side of the sensor. That the KCl will not flow out immediately, the KCl is here solved in a gel. As our last example for your question, if measured in deionized water the KCl can deplete faster, then a KCl storage vessel is connected to the sensor to keep the reference filled.
Would you be able to briefly explain the stirring effect and why it affects the pH measurement? And also if there is a way to measure the pH or ion concentration (using ion selective electrodes) of flowing liquids?
Why should Bubble (KCL 3 / Mol ) should be stored at the end of the electrode in a solution? While all components of has been working electrode into the solution.
Because of the KCl concentration in the reference half-cell is 3M KCl the sensor has to be stored in a 3 M KCl solution. Otherwise the KCl concentration in the reference will change due the diffusion law. If there is a semipermeable membrane between two solution with different concentration of ions, than the liquids are forced by the diffusion law to equal their concentrations. Therefore the ions from the higher concentration will invade the solution with the lower concentration the both liquids are equal. The same will happen to a pH reference cell, because the junction of the reference cell is a kind of semipermeable membrane. If the sensor is stored in destillated water, e.g., all the KCl moleculs will leave the reference cell to equal the concentration of the water. That will lead to a decreasing of the KCl concentration in the reference cell and to a change of the redox-potential. And this again will lead to a wrong measurement value. A characteristic sign for a bleeded reference is a shift of the zeropoint
I'm really thanksfull (I', learning write and speak english), I had see thw video several times..but ist I'm looking for, I read many text in spanish, and didn't understand, always the same cuestion..but how the solution provoque a difference potential???.. Until I saw this video..Tanks x1000 from Ecuador.
For questions like this please contact our Sales Center near you. They will be glad to answer your request. For contact data please look at www.endress.com/en/contact Thank you in advance!
For further information regarding the production of this animation, please contact our external movie producer Dipl. Des. B. Terstegge (terstegge@email.de)
The KCl is an almost ideal electrolyte because the mobility of the K + ion and the Cl- ion is almost equal. Because of that the potential difference in the salt bridge is reduced to a few millivolts or less. ;)
The advantage of the KCl solution is the good electrical conductivity (thus connected to the drainage electrode), the chemical neutrality and tendentious reaction inertia. Reactions of the membrane glass and the anions of the buffer are suppressed with the presence of the potassium chloride solution, ie with a higher concentration of KCl a decrease of the leaching and thus a reduction of the voltage drift is shown. One uses just a 3 molar solution, since this is an approximately saturated solution. For low temperature applications, 1.5 molar KCl solutions are used as the potential for solution decreases at lower temperatures. Another advantage of KCl is that the ions (K+ and Cl-) have the same migration rate, because otherwise a different diffusion velocity can lead to an interference potential (diffusion potential), ie different concentrations at the phase boundary.
Sir how can we determine pka of unknown solution using graph? I'm confused with equivalent and half equivalent point. I'm not understanding which point we have to select for correct pKa value. Can you please tell me with reference of any book or anything else. Thanks 😊
@Hemalsinh Rathod: the sensor in this video is a CPS11D. If this sensor is kept dry, the gel layer at the bulb will get dry as well. This will lead to a deterioration of the measuring performance. This deterioration depends on the time, the sensor is kept dry. If it is only for 15 minutes it wouldn't matter. The measurement is immediately proper. After a few hours the sensor needs a longer time to regenerate and to provide a stable signal. If the sensor is dry for e.g. the whole weekend or longer than it is highly recommended to put it into 3M KCl for 24 hours for regeneration. Conclusion: The deterioration of the measuring performance depends on the time the sensor is kept dry. The longer the dry-period, the longer the regeneration time. But it is always possible to regenerate it.
The size of the cations doesn't have any impacton a pH sensor because we are talking about a potentiometric measuring system. As long as there are ions in the media (cations and anions) independent of the size, a pH measurement with a sensor is possible.
Endress+Hauser one more thing if pH is based on potentiometeric principle then won't it detect potential difference due to all cations present in soil and not only H+ ions?
The potential difference in the case of pH is only influenced by H+- ions. The reason is the special glass on the measuring part of the sensor, where there is a gel layer on (thickness of 0.0001 mm) which is ion selective, in this case H+. If there is an excess of H+-ions in the media this will "stick" on this layer and the charge will be positive. With lack of H+-ions the charge will be negative.
This presentation was created in cooperation with an external partner (www.wiegaertner.com). They are working with a software called "Maya". For more information please contact our partner directly.
