SOLVED

51) The isomerization reaction, CH3NC → CH3CN, is first order and the rate constant is equal to 0.46 s-1 at 600 K. What is the concentration of CH3NC after 0.20 minutes if the initial concentration is 0.30 M? A) 1.2 × 10-3 M B) 2.7 × 10-3 M C) 1.2 × 10-1 M D) 2.7 × 10-1 M 52) The following reaction is first order, C2H6 → 2 CH3. If the rate constant is equal to 5.5 × 10-4 s-1 at 1000 K, how long will it take for 0.35 mol of C2H6 in a 1.00 L container to decrease to 0.20 mol in the same container? A) 4.5 min B) 17 min C) 53 min D) 65 min 53) The rate constant, k, for a first-order reaction is equal to 4.2 × 10-4 s-1. What is the half-life for the reaction? A) 2.9 × 10-4 s B) 1.2 × 103 s C) 1.7 × 103 s D) 2.4 × 103 s 54) The first-order reaction, SO2Cl2 → SO2 + Cl2, has a half-life of 8.75 hours at 593 K. How long will it take for the concentration of SO2Cl2 to fall to 16.5% of its initial value? A) 0.143 hr B) 2.28 hr C) 6.99 hr D) 22.7 hr 55) For the first-order reaction, 2 N2O(g) → 2 N2(g) + O2(g), what is the concentration of N2O after 3 half-lives if mol of N2O is initially placed into a 1.00-L reaction vessel? A) 1.6 × 10-2 M B) 3.1 × 10-2 M C) 6.2 × 10-2 M D) 1.2 × 10-1 M 56) Carbon-14, which is present in all living tissue, radioactively decays via a first-order process. A one-gram sample of wood taken from a living tree gives a rate for carbon-14 decay of 13.6 counts per minute. If the half-life for carbon-14 is 5720 years, how old is a wood sample that gives a rate for carbon-14 decay of 11.9 counts per minute? A) 5.3 × 102 yr B) 7.6 × 102 yr C) 1.1 × 103 yr D) 9.4 × 103 yr 57) In aqueous solution, hypobromite ion, BrO-, reacts to produce bromate ion, BrO3-, and bromide ion, Br-, according to the following chemical equation. A plot of 1/[BrO-] vs. time is linear and the slope is equal to 0.056 M-1s-1. If the initial concentration of BrO- is 0.80 M, how long will it take one-half of the BrO- ion to react? A) 4.5 × 10-2 s B) 7.1 s C) 12 s D) 22 s 58) The second-order reaction 2 Mn(CO)5 → Mn2(CO)10, has a rate constant equal to 3.0 × 109 M-1 s-1 at 25°C. If the initial concentration of Mn(CO)5 is 2.0 × 10-5 M, how long will it take for 90.% of the reactant to disappear? A) 6.7 × 10-16 s B) 7.4 × 10-15 s C) 1.5 × 10-4 s D) 6.0 × 103 s 59) Nitrogen dioxide decomposes at 300°C via a second-order process to produce nitrogen monoxide and oxygen according to the following chemical equation. 2 NO2(g) → 2 NO(g) + O2(g). A sample of NO2(g) is initially placed in a 2.50-L reaction vessel at 300°C. If the half-life and the rate constant at 300°C are 11 seconds and 0.54 M-1 s-1, respectively, how many moles of NO2 were in the original sample? A) 0.17 mol B) 0.42 mol C) 5.9 mol D) 15 mol 60) Hydrogen iodide decomposes at 800 K via a second-order process to produce hydrogen and iodine according to the following chemical equation. 2HI(g) → H2(g) + I2(g) At 800 K it takes 142 seconds for the initial concentration of HI to decrease from 6.75 × 10-2 M to 3.50 × 10-2 M. What is the rate constant for the reaction at this temperature? A) 5.12 × 10-4 M-1s-1 B) 9.69 × 10-2 M-1s-1 C) 10.3 M-1s-1 D