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John Schreifels @GMU: What is the balanced reaction at the cathode for the following galvanic cell?Cr(s)| Cr3+(aq) || Cu2+(aq) | Cu(s)

@X@user.full_name@X@ @GMU: How much time in minutes would it take for a 1.8567 g sample of 235U to decay to a mass of 1.3087 g if it has a half-life of 7.800e8 s.

@X@user.full_name@X@ @GMU: The osmotic pressure of an unknown solution is 0.853 atm at 17.61 °C. Which of the solutions below is the most likely one? Assume any salt is completely ionic!

John Schreifels @GMU: What is the total entropy change at 25oC for the reaction below, if the standard entropies of reactants and products are So(C(gr)) = 5.74 J/mol*K, So (H2(g)) = 130.68 J/mol*K, and So (C8H8(g)) = 345.2600J/mol*K and the heat of formation of C8H8(g)) is 147.8500 kJ/mol.C8H8(g) → 8C(gr) + 4H2(g)

@X@user.full_name@X@ @GMU: The cell potential was -4.59e-2 V at 25oC and a Sn2+(aq) concentration of 0.131 M. What was the hydronium ion concentration? The H2(g) pressure was 1 atm at 25oC.2H+(aq) + Sn(s) → Sn2+(aq) + H2(g) Ecoell = 0.140 V

John Schreifels @GMU: What is the total entropy change at 25oC for the reaction below, if the standard entropies of reactants and products are So (C(gr)) = 5.74 J/mol*K, So (H2(g)) = 130.68 J/mol*K, and So (C6H12(l)) = 204.4000 J/mol*K and the heat of formation of C6H12(l)) is -156.4000 kJ/mol.6C(gr) + 6H2(g) → C6H12(l)

@X@user.full_name@X@ @GMU: By how much would the rate of reaction (see below) change if the concentration of CO increased by a factor of 2.140. The rate law of this reaction is Rate = k[NO2]2.NO2(g) + CO(g) → CO2(g) + NO(g)

John Schreifels @GMU: What is the change in mass of 87Rb when it is formed from protons, electrons and neutrons if the atom has a mass of 86.909187 amu? The masses of the proton, electron and neutron are 1.00728 amu, 0.000549 amu and 1.00867 amu, respectively.

@X@user.full_name@X@ @GMU: What is the pH of 1.34e-4 M HClO4 ?

@X@user.full_name@X@ @GMU: What is the pH of a 0.1249 M CH3COOH ? See reaction belowCH3COOH + H2O → CH3COO- + H3O+ Ka = 1.760×10-5