SOLVED

41) Derive an expression for a “1/3-life” for a first-order reaction. A) B) C) D) E) 42) Derive an expression for a “1/4-life” for a first-order reaction. A) B) C) D) E) 43) The first-order decay of radon has a half-life of 3.823 days. How many grams of radon remain after 7.22 days if the sample initially weighs 250.0 grams? A) 4.21 g B) 183 g C) 54.8 g D) 76.3 g E) 67.5 g 44) The first-order decay of radon has a half-life of 3.823 days. How many grams of radon decomposes after 5.55 days if the sample initially weighs 100.0 grams? A) 83.4 g B) 16.6 g C) 50.0 g D) 36.6 g E) 63.4 g 45) The first-order decomposition of N2O5 at 328 K has a rate constant of 1.70 × 10-3 s-1. If the initial concentration of N2O5 is 2.88 M, what is the concentration of N2O5 after 12.5 minutes? A) 0.124 M B) 0.805 M C) 2.82 M D) 0.355 M E) 0.174 M 46) The second-order decomposition of NO2 has a rate constant of 0.255 M-1s-1. How much NO2 decomposes in 4.00 s if the initial concentration of NO2 (1.00 L volume) is 1.33 M? A) 1.8 mol B) 0.85 mol C) 0.48 mol D) 0.77 mol E) 0.56 mol 47) For a reaction, what generally happens if the temperature is increased? A) A decrease in k occurs, which results in a faster rate. B) A decrease in k occurs, which results in a slower rate. C) An increase in k occurs, which results in a faster rate. D) An increase in k occurs, which results in a slower rate. E) There is no change with k or the rate. 48) Identify the rate-determining step. A) the slowest step B) the faster step C) the fast step D) always the last step E) always the second step 49) The first-order rearrangement of CH3NC is measured to have a rate constant of 3.61 × 10-15 s-1 at 298 K and a rate constant of 8.66 × 10-7 s-1 at 425 K. Determine the activation energy for this reaction. A) 160. kJ/mol B) 240. kJ/mol C) 417 kJ/mol D) 127 kJ/mol E) 338 kJ/mol 50) A reaction is followed and found to have a rate constant of 3.36 × 104 M-1s-1 at 344 K and a rate constant of 7.69 M-1s-1 at 219 K. Determine the activation energy for this reaction. A) 23.8 kJ/mol B) 42.0 kJ/mol C) 11.5 kJ/mol D) 12.5 kJ/mol E