@X@user.full_name@X@ @GMU: What is the fraction of A remaining after 96.231 minutes if the first order rate constant is 2.100e-4 s-1?

@X@user.full_name@X@ @GMU: What is the pOH of 2.54e-4 M HBr?

@X@user.full_name@X@ @GMU: How much energy in kJ is released to form one mole of 95Mo from protons, electrons, and neutrons if the nucleus has a mass of 94.905841 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: Calculate the pOH of 103.74 mL of a buffer initially consisting of 0.1767 M CH3(CH2)2CH2NH2 and 0.2060 M CH3(CH2)2CH2NH3Br after addition of 0.0025 mol of HCl. Assume that no volume change occurs after addition of the acid. The Kb of CH3(CH2)2CH2NH2 is 4.10e-4

@X@user.full_name@X@ @GMU: Hydrogen iodide decomposes at 410°C according to second order kinetics (see reaction below). The half-life for this reaction was measured to be 4.08e3 s when the initial concentration of HI was 7.96e-3 M. What is the rate constant for this reaction?HI(g) → H2(g) + I2(g)

@X@user.full_name@X@ @GMU: LiBr 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 Br- if the ionic radius of Li+ is 80.07 pm and the density of LiBr is 3.464 g/cm3?

@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 would the pOH be after addition of 16.54 mL of 0.1000 M NaOH to 25.00 mL of 0.1000 HA (a weak acid, Ka = 9.23e-5)?

@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 0.1567. 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 fraction of A remaining after 83.913 minutes if the first order rate constant is 1.037e-4 s-1?