@X@user.full_name@X@ @GMU: Radioactive substances decay by first-order kinetics. How many days would be required for a sample containing neptunium-93 to decrease to 66.22% of its initial activity? The half-life of neptunium-93 is 2.35 days.

@X@user.full_name@X@ @GMU: Initially there were equilibrium concentrations of 0.1041 M A, 0.3333 M B, and 0.1041 M C. Which change will cause Qc to be greater than Kc? Use the reaction below.5A → 3 B +3 C Kc = 0.904

John Schreifels @GMU: When 0.1237 g of urea was dissolved in 106.3 mL of water, the osmotic pressure at 14.20°C was 0.4572 atm. What is the formula mass of this compound?

@X@user.full_name@X@ @GMU: What is the freezing point depression when 19.32 g of Ba(NO3)2 (formula mass = 199.30 g/mol) is dissolved in 189.16 g H2O? The freezing point depression constant is 1.8600 (°C*kg)/mol. Assume any salt is completely ionic!

@X@user.full_name@X@ @GMU: Initially there were equilibrium concentrations of 0.1755 M A, 0.2500 M B, and 0.1755 M C. Which change will cause the equilibrium to shift from left to right? Use the reaction below.4A → 4 B +3 C Kc = 0.663

@X@user.full_name@X@ @GMU: Initially there were equilibrium concentrations of 0.3076 M A, 0.2369 M B, and 0.1811 M C. Which change will cause the equilibrium to shift from left to right if the reaction is exothermic? Use the reaction below.5A(aq) → 2B(aq) +4C(aq) K = 1.376

@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 7.67e-4 M-1s-1 at 346.45°C?H2(g) + I2(g) → 2HI(g)

Consider the reaction.4NH3(g) + 5O2(g) ⇋4NO(g) + 6H2O(l)What is the correct expression for Kc?

@X@user.full_name@X@ @GMU: What is the value of Kc at 226.85 °C for the reaction below if Kp is 6.24e-3 at this temperature?CO(g) + 2H2(g) → CH3OH(g)

What would be the expected rate law for the mechanism described below?1 O3(g) + HO(g) → HO2(g) + O2(g) fast 2 HO2(g) + O → OH(g) + O2(g) slow