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In electrochemistry, the Nernst equation is a chemical thermodynamical relationship that permits the calculation of the reduction potential of a reaction (half-cell or full cell reaction) from the standard electrode potential, absolute temperature, the number of electrons involved in the redox reaction, and activities (often approximated by concentrations) of the chemical species undergoing ...
Most commonly, a solution containing the metal ion and the ligand in a medium of high ionic strength is first acidified to the point where the ligand is fully protonated. This solution is then titrated , often by means of a computer-controlled auto-titrator, with a solution of CO 2 -free base.
When the electrode is calibrated with solutions of known concentration, by means of a strong acid–strong base titration, for example, a modified Nernst equation is assumed. E = E 0 + s log 10 [ A ] {\displaystyle E=E^{0}+s\log _{10}\mathrm {[A]} }
The relative activity of a species i, denoted a i, is defined [4] [5] as: = where μ i is the (molar) chemical potential of the species i under the conditions of interest, μ o i is the (molar) chemical potential of that species under some defined set of standard conditions, R is the gas constant, T is the thermodynamic temperature and e is the exponential constant.
It is the same concept as volume percent (vol%) except that the latter is expressed with a denominator of 100, e.g., 18%. The volume fraction coincides with the volume concentration in ideal solutions where the volumes of the constituents are additive (the volume of the solution is equal to the sum of the volumes of its ingredients).
Indeed, for ideal-gas reactions K p is independent of pressure. [17] Pressure dependence of the water ionization constant at 25 °C. In general, ionization in aqueous solutions tends to increase with increasing pressure. In a condensed phase, the pressure dependence of the equilibrium constant is associated with the reaction volume. [18] For ...
The equilibrium, between the gas as a separate phase and the gas in solution, will by Le Châtelier's principle shift to favour the gas going into solution as the temperature is decreased (decreasing the temperature increases the solubility of a gas). When a saturated solution of a gas is heated, gas comes out of the solution.
The acidic protons H + in solution react to form hydrogen gas (Reaction 7) whilst iron(II) oxidises in the positive half-cell (Reaction 6). The HER is pH dependent. The HER is pH dependent. At lower pH values, the concentration of H + is high, which increases the kinetics of the side reaction.