In organic solvent such as DMSO, DMF, and Acetone, is it possible to measure pH of solvent or is the parameter of pH applied for this kind of medium?
and if the answer is yes, how could change the pH in organic medium?
The pH concept can be applied to non aqueous solutions because the proton activity term is applicable to organic medium as well as to water. The glass electrode works properly in many polar solvents, including DMSO, DMF and aqueous acetone (up to 80% of acetone). In such case the key point is the standard state which you choose to determine the proton activity. When the common aqueous buffer solutions are used for pH meter calibration the obtained pH for non aqueous medium is so called instrumental value. It is necessary to correct it for junction potential (diffusion potential occurring between aqueous filling of reference electrode and outer organic solution) and the energy of proton transfer from infinitely diluted aqueous solution to the same non aqueous solution. Both types of correction values are known in literature for wide range of organic and mixed solvents (for instance, see the publications of R. Bates or N. Izmailov). Using such approach You can obtain so called pa (H+) values i.e. proton activities referred to infinitely diluted solution in particular solvent as standard state.
The concept of pH is technically limited to aqueous solutions as it is based on the logarithm of the equilibrium process of the autoionization of water. However, the same ideas do apply to other mediums. Meaning acidity and basicity measures are still used. Another fairly common solvent for those types of measurements is dimethyl sulfoxide (Bordwell pKa table is a common and useful example of this).
Most pH measurement processes are not extensible to organic solvents however. This is because common pH meters rely on electric current/charge transduction through the solution. Most organic solvents are not conductive to any appreciable extent (large resistivity). Hope this helps. Bronsted-Lowry acidity is pretty interesting to think about.
pH is exactly effective on the organic solution, and can change medium chemically with infuencing the organic molecules.
i offer you change pH in the organic medium by adding organic acid such as acetic acid, citric acid, and etc.
The pH concept can be applied to non aqueous solutions because the proton activity term is applicable to organic medium as well as to water. The glass electrode works properly in many polar solvents, including DMSO, DMF and aqueous acetone (up to 80% of acetone). In such case the key point is the standard state which you choose to determine the proton activity. When the common aqueous buffer solutions are used for pH meter calibration the obtained pH for non aqueous medium is so called instrumental value. It is necessary to correct it for junction potential (diffusion potential occurring between aqueous filling of reference electrode and outer organic solution) and the energy of proton transfer from infinitely diluted aqueous solution to the same non aqueous solution. Both types of correction values are known in literature for wide range of organic and mixed solvents (for instance, see the publications of R. Bates or N. Izmailov). Using such approach You can obtain so called pa (H+) values i.e. proton activities referred to infinitely diluted solution in particular solvent as standard state.
What if I have to actually measure the pH of organic mixture?
This mixture contains 3, 4 xylidene, 3-pentanone and benzene.I am adding glacial acetic acid to make the solution acidic.I have to monitor the pH in between 5 to 6
Since pH meters rely on electric current flow through the solution to the sensor/probe and organic solvents are not conductive, I will suggest you make use of the Universal pH paper indicator that changes colour for pH range of 1 – 14 and it has a colour band for comparison.
Hi, Let me know the best solvent for Poly (Ethylene-co-acrylic acid) ? Can anybody reply me up to the mark.
I want to know what is the best method to measure pH of NMP solvent
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