## How pH meters use the Nernst Equation

$E_{cell} = E_{cell}^{\circ}-\frac{RT}{nF}\ln Q$

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### How pH meters use the Nernst Equation

In lecture today we discussed the nernst equation and how it can pH meters use it to calculate solutions pH. I understand the general idea that the meter will use the electric potentials and knowledge that within the [p](product concentration) is the H+ ion concentration of the solution, which determines pH. However, I am a bit confused on how the meter knows what the electric potentials are and how from knowing [P] and [R] it can isolate the H+ concentration.

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### Re: How pH meters use the Nernst Equation

pH meters measure the potential of the cell via an electronic circuit. It also knows what the standard reaction inside the electrode is so it can determine Eo and n. The electronics then do the math to determine what the reaction quotient is. Since there is a set concentration within the electrode, the concentration of ions in solution is easily determined from Q.

Return to “Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)”

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