241.0046g/mol = 236.9970g/mol + 4.0015g/mol + mass defect mass defect = 0.0061g/mol = 6.1 x 10 -3 g/mol = 6.1 x 10 -6 kg/mol E = mc 2 (6.1 x 10 -6 kg) x (3 x 10 8 m/s) 2 x (1J/kgm 2 s -2 ) = 5.49 x 10 11 J
Chem 162-2012 final exam + solutions 46 45 Chem 162-2012 Final Exam + Answers Chapter 19 – Electrochemistry Free energy, equilibria and cell potential calculations/Nernst equation Which of the following changes would increase the measured cell potential of a galvanic cell represented by Cu(s) | Cu2+(1.0 M) || Ag+(1.0 M) | Ag(s) X. Add NaCl to the silver compartment to precipitate AgCl Y. Increase the size the solid copper electrode Z. Add Na2S to the copper compartment to precipitate CuS A. Y and Z B. X only C. Z only D. X and Z E. none would increase the cell potential ET note: I have been describing the “cell potential” as “cell voltage”, not “cell potential”. B&O and the writer of this problem calls it cell potential. They mean the same thing. According to line notation convention, left side is anode (oxidation); right side is cathode (reduction). Cu(s) → Cu 2+ + 2e - 1.0M Ag + + 1e - → Ag(s) 1.0M Cu(s) + 2Ag + (1.0M) → Cu 2+ (1.0M) + Ag(s) Based on the Nernst equation, and/or LeChatelier’s Law, decreasing the concentration of products, and/or increasing the concentration of reactants, would drive the reaction to the right, making it more spontaneous (i.e., making the cell potential more positive). X. Removal of Ag + will drive the reaction to the left, and lower the cell potential. Y. Increasing the size of an electrode will have no effect on the molarity of the electrode, and would therefore have no effect on the equilibrium. Z. Adding Na 2 S to the Cu 2+ would reduce the concentration of the Cu 2+ , which will drive the reaction to the right, making it more spontaneous, and therefore increase the cell potential.
Chem 162-2012 final exam + solutions 47 46 Chem 162-2012 Final Exam + Answers Chapter 20 – Nuclear Chemistry Miscellaneous Which of the following is notcurrently a use of radioisotopes by man?
Chem 162-2012 final exam + solutions 48 47 Chem 162-2012 Final Exam + Answers
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