Standard reduction potentials. 667 table

FIGURE 14.3 Mnemonic devices, the arrows on the left, for predicting which chemicals will participate in a redox reaction and which will not. A segment of the table of standard reduction potentials (Table 14.1) is presented on the right as a help to understand the use of the arrows. See text for an example. 

A voltaic cell converts chemical energy into electrical energy. It consists of two parts called half-cells. When two different metals, one in each half-cell, are used in the voltaic cell, a potential difference is produced. In this experiment, you will measure the potential difference of various combinations of metals used in voltaic cells and compare these values to the values found in the standard reduction potentials table. 

Applying Concepts Write the half-reactions for the anode and cathode in each of the voltaic cells in the data table. Look up the half-reaction potentials from the standard reduction potentials table (Table 21-1) and record these in the data table. 

Why is lithium metal becoming a popular electrode in modern batteries Use the standard reduction potentials table to help you answer this question. 

The following problem can be solved using standard reduction potentials (Table 6-8). Use E0 ... 

Table 20.2 lists standard potentials E° for oxidation of first-series transition metals. Note that these potentials are the negative of the corresponding standard reduction potentials (Table 18.1, page 775). Except for copper, all the E° values are positive, which means that the solid metal is oxidized to its aqueous cation more readily than H2 gas is oxidized to H+(aq). 

Once an ore has been concentrated, it is reduced to the free metal, either by chemical reduction or by electrolysis. The method used (Table 21.2) depends on the activity of the metal as measured by its standard reduction potential (Table 18.1). The most active metals have the most negative standard reduction potentials and are the most difficult to reduce the least active metals have the most positive standard reduction potentials and are the easiest to reduce. 

The table below lists the cell potentials for the 10 possible galvanic cells assembled from the metals A, B, C, D, and E, and their respective 1.00 M 2+ ions in solution. Using the data in the table, establish a standard reduction potential table similar to Table 11.1 in the text. Assign a reduction potential of 0.00 V to the half-reaction that falls in the middle of the series. You should get two different tables. Explain why, and discuss what you could do to determine which table is correct. 

Use the table of standard reduction potentials (Table 18.1) to pick a reagent that is capable of each of the following oxidations (under standard conditions in acidic solution). 

Tanis, D.O. (1990). Galvanic cells and the standard reduction potential table. Journal of Chemical Education, 57, 602-603. 

Solve We calculate ° for the cell from standard reduction potentials (Table 20.1 or Appendix E). The standard emf for this reaction was calculated in Sample Exercise 20.6 B° = 0.79 V. As that exercise shows, six electrons are transferred from reducing agent to oxidizing agent, so It = 6. The reaction quotient, Q, is... 

Calculate the equihbrium constant for the following reactions using data from the standard reduction potential tables given in Appendix I ... 

A chemical that appears at the bottom of the standard reduction potential table with a sizeable negative value means that the chemical being considered has a strong tendency to be oxidized (and very little tendency to be reduced). This observation is in line with expectations for alkah metals that tend to lose an electron easily to form mono-positive cations. 

Using standard reduction potentials (Table 20.1), determine whether the following reactions are spontaneous under standard conditions ... 

By devising various galvanic cells and measuring their electromotive forces, tables of values of standard electrode potentials can be constructed. A table that lists the value of electrode potential for any half-cell in which all concentrations are IM and all gases are at 1-atm pressure is a Table of Standard Reduction Potential (Table 3.2). By convention, the tabulated values are standard reduction potentials relative to the potential of the standard hydrogen electrode, which is defined as exactly zero volts. The analysis of the data from Table 3.2 highlights some important aspects. 

Pick a combination of two metals from the Standard Reduction Potential table (Table 20.1 or Appendix I) that would result in a cell with a potential of about -f 0.90 V. For your answer, write both the half-reactions, write the overall balanced reaction, and calculate the cell potential for your choice. 

From the table of standard reduction potentials (Table 2.1), the reduction potential of Cu is -F0.34 volts and that of Zn is —0.76 volts. The emf of the cell is positive. Hence the reduction is spontaneous and it should proceed from left to right. 

Table 4. Standard Reduction Potentials for Selected Manganese Compounds...

---