A voltaic cell is constructed using Hg/Hg+2 for one half-cell and Cr/Cr+3 for the other half-cell. The half-cells are at standard conditions and contain equal-mass electrodes and the same volume of solutions. Reference: Cr+3(aq) + 3 e- ---> Cr(s) E0 = -0.74 V; Hg+2(aq) + 2 e- ---> Hg(l) E0 = +0.80 V

(a) Write the balanced net ionic equation for the spontaneous reaction produced in the cell.

(b) Calculate the value of E0 for the spontaneous reaction.

(c) What is the value of the standard free-energy change, delta G0, for the spontaneous reaction? Use appropriate units with your answer.

(d) If the cell operates until [Cr+3] is 1.09 M in the Cr/Cr+3 half-cell, what is [Hg+2] in the Hg/Hg+2 half-cell?

(e) In another voltaic cell with the same half-cells, [Hg+2] is 1.00 M and [Cr+3] is 0.050 M. How should Ecell for this cell compare to the value in (b)? Justify your answer

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).