@X@user.full_name@X@ @GMU: Calculate the of 114.01 mL of a buffer initially consisting of 0.1752 M C2H5NH2 and 0.1926 M C2H5NH3Br after addition of 0.0031 mol of HCl. Assume that no volume change occurs after addition of the acid. The Kb of C2H5NH2 is 5.60e-4

@X@user.full_name@X@ @GMU: Determine the molality of a 6.831 wt % aqueous solution of LiBr.

@X@user.full_name@X@ @GMU: The osmotic pressure of an unknown solution is 747.829 mm Hg at 29.14 °C. Which of the solutions below is the most likely one? Assume any salt is completely ionic!

@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 0.1461. 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.

@X@user.full_name@X@ @GMU: What is the activation energy (in kJ/mol) for the reaction below if the rate constants are 2.700e-4 M-1s-1 at 327.00°C and 8.80e-4 M-1s-1 at 349.11°C?H2(g) + I2(g) → 2HI(g)

@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 1.14e-7?4C2H2(g) + 3 H2(g) → C8H14(g) ΔGo = -601.570 kJ.

@X@user.full_name@X@ @GMU: LiCl has a face-centered cubic unit cell in which the Cl- anions occupy corners and face centers, while the cations fit into the hole between adjacent anions. What is the radius of Li+ if the ionic radius of Cl- is 181.0 pm and the density of LiCl is 2.068 g/cm3?

John Schreifels @GMU: What is the balanced reaction for the following galvanic cell?Ni(s)| Ni2+(aq) || Fe3+(aq) | Fe(s)

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 (C5H8(g)) = 331.1100J/mol*K and the heat of formation of C5H8(g)) is 144.4200 kJ/mol.C5H8(g) → 5C(gr) + 4H2(g)

@X@user.full_name@X@ @GMU: When 0.3436 g of citric acid was dissolved in 100.1 mL of water, the osmotic pressure at 14.13°C was 0.4212 atm. What is the formula mass of this compound?