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@X@user.full_name@X@ @GMU: How much energy in kJ is released to form one mole of 116Cd from protons, electrons, and neutrons if the nucleus has a mass of 115.904755 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 standard free energy change for the ionization of H2O acid, if its Ka is 1.00e-14.

@X@user.full_name@X@ @GMU: The pH of a solution of HClO3 was 3.254. What was the hydronium ion concentration?

@X@user.full_name@X@ @GMU: To what temperature would you have to heat bromine, Br2,(l) to cause its vapor pressure to become 402.4 mm Hg if its heat of vaporization and boiling point are 31.40 kJ/mol and 331.9 K, respectively?

@X@user.full_name@X@ @GMU: What is the free energy change for the reaction below, if the reaction quotient, Q, at 25.0oC is equal to 1.18e-6?C2H2(g) H2(g) → C2H4(g) ΔGo = -141.144 kJ.

@X@user.full_name@X@ @GMU: RbBr has a face-centered cubic unit cell in which the Br- anions occupy corners and face centers, while the cations fit into the hole between adjacent anions. What is the radius of Rb+ if the ionic radius of Br- is 195.0 pm and the density of RbBr is 3.350 g/cm3?

@X@user.full_name@X@ @GMU: What is the temperature at which the reaction below becomes spontaneous, if the standard entropies of reactants and products at 25oC are So (C(gr)) = 5.74 J/mol*K, So(H2(g)) = 130.68 J/mol*K, and So (C9H16(g)) = 484.8200J/mol*K and the heat of formation of C9H16(g)) is 61.8300 kJ/mol?C9H16(g) → 9C(gr) + 8H2(g)

@X@user.full_name@X@ @GMU: When 0.3676 g of citric acid was dissolved in 104.9 mL of water, the osmotic pressure at 26.69°C was 0.4491 atm. What is the formula mass of this compound?

John Schreifels @GMU: What must the reaction quotient Q be, if the free energy is -1.04e3 kJ at 25.0oC?5C2H2(g) + 6 H2(g) → C10H22(g) ΔGo = -1.01e3 kJ.

@X@user.full_name@X@ @GMU: Uranium -238 decays in a series of steps to Pb-206. When the material is very old, one can treat the kinetics as a decay directly to Pb and the ratio of these two can be treated as a measure of the age of a rock. A rock containing 238U and 206Pb was examined to determine its approximate age. The molar ratio of 206Pb to 238U was 0.1950. Assuming no lead was originally present and that all lead formed remained in the rock, what is the age of the rock (in years)? The half-life of 238U is 4.50e9 yr.