Electrode potentials standard cell potential

The Nernst equation is used to calculate electrode potentials or cell potentials when the concentrations and partial pressures are other than standard state values. The Nernst equation using both base 10 and natural logarithms is given by ... 

To calculate the open circuit voltage of the lead—acid battery, an accurate value for the standard cell potential, which is consistent with the activity coefficients of sulfuric acid, must also be known. The standard cell potential for the double sulfate reaction is 2.048 V at 25 °C. This value is calculated from the standard electrode potentials for the (Pt)H2 H2S04(yw) PbS04 Pb02(Pt) electrode 1.690 V (14), for the Pb(Hg) PbS04 H2S04(yw) H2(Pt) electrode 0.3526 V (19), and for the Pb Pb2+ Pb(Hg) 0.0057 V (21). 

When the two electrodes are connected, current flows from M to X in the external circuit. When the electrode corresponding to half-reaction 1 is connected to the standard hydrogen electrode (SHE), current flows from M to SHE. (a) What are the signs of ° of the two half-reactions (b) What is the standard cell potential for the cell constructed from these two electrodes ... 

Stalactites, 15 29 Stalagmites, 15 29 Stalk fibers, 21 18 Stamp-pad inks, 14 328 Standard cell potential, 15 750 Standard deviation, 13 257, 20 699 Standard electrode potential selected ions, 7 799t... 

The standard cell potential for the reduction of hydrogen ions to hydrogen gas is, by definition, 0.00 V. This potential is for the standard hydrogen electrode, SHE, which is the reference to which we compare all other cell potentials. All metals above hydrogen on the Activity Series will displace hydrogen gas from acids. (See Chapter 4) Metals below hydrogen will not displace hydrogen gas. 

First of all, the important role of platinum as the metal part of the standard hydrogen electrode (SHE), which is the primary standard in electrochemistry should be mentioned. The standard potential of an electrode reaction (standard electrode potential) is defined as the value of the standard potential of a cell reaction when that involves the oxidation of molecular hydrogen to solvated (hydrated) protons (hydrogen ions) ... 

A positive standard cell potential tells you that the cathode is at a higher potential than the anode, and the reaction is therefore spontaneous. What do you do with a cell that has a negative " gii Electrochemical cells that rely on such nonspontaneous reactions cire called electrolytic cells. The redox reactions in electroljdic cells rely on a process called electrolysis. These reactions require that a current be passed through the solution, forcing it to split into components that then fuel the redox reaction. Such cells are created by applying a current source, such as a battery, to electrodes placed in a solution of molten salt, or salt heated until it melts. This splits the ions that make up the salt. 

The standard cell potential for the zinc electrode for the oxidation of zinc metal to zinc ion is 0.76 volt. 

Calculate the standard cell potential of a cell constructed with nickel (Ni) and copper (Cu) electrodes. 

The V is the voltmeter reading. The question to ask, therefore, is What potentials are maintained constant when one measures a number of electrode potential in cells that always contain a standard hydrogen electrode (SHE) ... 

In this expression, E° is the standard cell potential, the cell potential measured when all the species taking part are in their standard states. In practice, that means all gases are at 1 bar and all ions are at 1 mol-L 1. For example, to measure the standard potential of the Daniell cell, we should use 1 M CuS04(aq) in one electrode compartment and 1 M ZnS04(aq) in the other. 

There are thousands of possible galvanic cells and therefore many thousands of possible standard cell potentials. Instead of thinking of all these different cells, it is much simpler to think of each electrode as making a... 

The value quoted here, like all the values in this text, is for 25°C. Because, according to convention, the hydrogen electrode contributes 0 to the standard cell potential, the standard potential of the cell, 0.76 V, can be attributed entirely to the zinc electrode. Moreover, because the zinc electrode is known by experiment to be the anode, its standard potential is subtracted from that of hydrogen ... 

Determine the standard potential of an electrode from a cell potential, Example 12.4. 

M) half-cell and a standard hydrogen electrode. Electrons flow from the zinc anode to the S.H.E. (cathode). The measured standard cell potential at 25°C is 0.76 V. 

E°, the standard cell potential, is equal to the difference between the standard electrode potentials. 

The standard cell potentials we have been discussing refer to cells in which all dissolved substances are at unit activity, which essentially means an effective concentration of 1M. Similarly, any gases that take part in an electrode reaction are at an effective pressure (known as the fugacity) of 1 atm. If these concentrations or pressures have other values, the cell potential will change in a manner that can be predicted from the principles you already know. 

The standard potential of an -> electrode reaction (standard electrode potential) is defined as the value of the standard potential of a cell reaction (E ) when that... 

Absolute Single Electrode Potentials.— The electrode potentials discussed hitherto are actually the e.m.f. s of cells resulting from the combination of the electrode with a standard hydrogen electrode. A single electrode potential, as already seen, involves individual ion activities and hence has no thermod3mamic significance the absolute potential difference at an electrode is nevertheless a quantity of theoretical interest. Many attempts have been made to set up so-called null electrodes ... 

Table 8.3 lists a few representative standard electrode potentials (or reduction potentials). Figure 8.6 exemplifies the principle of an electrochemical cell. The hydrogen electrode is made up of a B-electrode (which does not participate directly in the reaction), which is covered by H2(g), which acts as a redox partner [H2(g) = 2H +2e ]. Pt acts as a catalyst for the reaction between H and H2(g) and acquires a potential characteristic of this reaction. The salt bridge between the two cells contains a concentrated solution of salt (such as KCl) and allows ionic species to diffuse into and out of the half-cells this permits each half-cell to remain electrically neutral. 

The standard cell potential, E °, is the difference between the standard potentials of the electrode on the right side of the diagram and the electrode on the left side of the diagram. 

If the chloride of the metal is not suitable, for one reason or another, the sulfate may prove satisfactory. In this event a sulfate reference electrode, e.g., SO", Hg 04( ), Hg may be employed in place of the mlver chloride electrode. The standard (reduction) potential of this electrode has been found to be 0.6141 volt at 25 C, by means of measurements simitar to those described in connection with the diver chloride cell in 39h. 

M An electrode potential is the potential of a cell that has a standard hydrogen electrode a.s the left electrode (reference). 

We saw in Section 21-12 that the zinc-hydrogen cell operated with oxidation at the zinc electrode and reduction at the hydrogen electrode, with a standard cell potential of 0.763 V... 

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