CHEM 1046 MIDTERM PRETEST QUESTIONS LATEST 2023

CHEM 1046 MIDTERM PRETEST QUESTIONS LATEST 2023 1. What is the intermediate in the following mechanism? A + B  C + D B + D  X A) A B) B C) C D) D E) X 2. Calculate the activation energy of a reaction that has a rate constant of 4.41 x 10-3s- 1 at 78 K and rate constant of 9.79 x 10-2s-1 at 315 K. A) 2.67 kJ/mol B) 2.90 kJ/mol C) 0.0589 kJ/mol D) 22.4 kJ/mol E) 200.34KJ/mol 3. A chemical reaction that is 1st order in X is observed to have a rate constant of 1.2 X 10-2/sec. If the initial concentration of X is 2.0M, what is the concentration of X after 200 sec? A) [A]200 = 0.18 mol/L B) [A]200 = 0.32 mol/L C) [A]200 = 0.23 mol/L D) [A]200 = 0.67 mol/L 4. For a certain second-order decomposition reaction, the rate is determined to be 0.30 mol /L•sec when the concentration of the reactant is 2.0M. What is the rate constant of the reaction? A) k = 0.023 L/mol sec B) k = 0.045 L/mol sec C) k = 0.075 L/mol sec D) k = 0.034 L/mol sec E) k = 0.005 L/mol sec 5. The rate constant for a reaction is 1.3/(M • s) at 700K and 23/(M • s) at 800K. What is the activation energy? A) Eact = 133,000 J B) Eact = 103,000 J C) Eact = 122,000 J D) Eact = 120,000 J E) Eact = 200,000 J 6. A certain radioactive decay process (1st order) is 45% complete in 65 sec. What are the rate constant and half-life for this process? A) k = 9.31 x 10-3/sec and t1/2 =74sec B) k = 3.34 x 10-3/sec and t1/2 =22sec C) k = 6.33 x 10-3/sec and t1/2 =56sec D) k = 2.31 x 10-3/sec and t1/2 =89sec E) k = 4.38 x 10-3/sec and t1/2 =14sec