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CHEM 113C, Spring 2009, Problem Set 1 DUE: Friday, April 10 Hand in during class or e-mail before class to [email protected]
Problem 1. V. L. Bohnson in J. Phys. Chem. 24 , 677 (1920) studied the rate of the irreversible reaction H 2 O 2 → H 2 O +1/2 O (^2) in water, catalyzed by NaI. The data he obtained are given in the table above. x represents the amount of H 2 O 2 decomposed and a is the initial amount. (1a) (20 points) Explain why the author does not give the units of x and a, nor does he tell us the volume of solution.
(1b) (20 points) How did he convert the volume of oxygen into milligrams of dry oxygen? Use a few of the volumes given by him and calculate the milligrams of oxygen. (1c) (20 points) Knowing how many milligrams of oxygen were produced, calculate how much H 2 O 2 was consumed and compare to x given in the table. (1d) (60 points) Guess a rate equation and calculate the rate constant. If you do not use Mathematica, use the simple method given in class. If you use Mathematica, perform a least-squares fitting. Test the quality of your result (i.e. see if you get a good fit of the data) (1e) (20 points) Calculate at what time you consume half of the H 2 O 2. (If you use Mathematica you have a model of such a calculation in Ch. 2 WorkBook.)
Problem 2. (20 points) Prove that if the reaction N 2 +3H 2 ↔ 2NH 3 goes from right to left then the extent of reaction decreases in time or is constant and it is negative.
Problem 3. You perform the reaction N 2 +3H 2 ↔ 2NH 3 with 0.3 mole of N 2 and 0.4 moles of H 2 in a container of 20 liters. (3a) (30 points) What is the maximum value that the extent of reaction η can take? (3b) (20 points) If at a given time the extent of reaction η is 0.1 mole/liter, calculate the concentration of H 2 , N 2 and NH 3 at that time.
