Arkansas State University Department of Chemistry and Physics

1 Write the rate expression in terms of D[reactant]/Dt  and  D[product]/Dt for the reaction:

    N₂       +   3 H₂   ------->   2 NH₃

2 Determine a) the order of each reactant, b) the order of the reaction, c) write the rate law and d) calculate the rate constant, k, for the following data:
 

Reaction	[A]	[B]	initial rate
1.	0.20 M	0.10 M	3.50 x 10-3 M/s
2.	0.40	0.10	7.00 x 10-3 M/s
3.	0.40	0.40	7.00 x 10-3 M/s

3a. The decomposition of A₂B₃ is second order with a k = 6.5 x 10^-5 M^-1s ^-1 at 25^oC.  If the initial concentration is 0.50 M, what is the concentration after 3 min?

b. What is the half-life for the reaction in question 3a?

4. The decomposition of AB is first order with a k = 2.3 x 10^-7 s^-1 at 45^oC.  If the initial concentration is 0.25 M, what is the concentration after 2.3 min?

b. What is the half-life for the reaction in question 4a?

5a. What is the concentration of reactant after 2.5 minutes if the inital concentration was 0.100 M and k = 6.93 x 10^-3 s^-1 for a first order reaction?

b. What is the half-life?

6. For the first order reaction:

  SO₂Cl₂      ----->     SO₂   + Cl₂

 How long will it take to reach 0.31 x 10^-3 M if the inital concentration was 1.25 x 10^-3 M and k = 0.17/hr?

7. For the second order reaction   A -----> B (k = 1.5 x 10^-2/Ms),

 a) if the initial concentration of A is 0.10M, what is the concentration of A after 4 min?

 b) what is the half-life?

answers