## CHM 112 Section 1

Homework Assignment #2
##### Due January 27, 2006 by 8:05 a.m.

Practice (not to be turned in): 13.1, 13.2, 13.23.

Consider the reaction:

[Co(NH3)5Cl]2+(aq) + [Co(CN)5]3–(aq) [Co(CN)5Cl]3–(aq) + Co2+(aq) + 5 NH3(aq)

The initial concentration of each reactant is equal to the eighth and ninth digits of your Student ID Number divided by 105 M = Cinit. At some temperature, after 12 s, the concentrations of each reactant are reduced to 0.93×Cinit.

1. What is the average rate of reaction for the first 12 s in terms of the loss of [Co(CN)5]3–?

2. Based on the definition of a rate, Rate = (0.93×Cinit – Cinit)/(12 – 0)

3. What is the average rate of reaction for the first 12 s in terms of the gain of NH3?

4. The stoichiometric ration between ammonia and the cobalt anion is 5:1, so the rate with respect to ammonia will be 5 times the rate with respect to [Co(CN)5]3–

5. The rate law at 25 oC is found to be Rate = k[Co(NH3)5Cl2+] [Co(CN)53–] with k=5×107 M–1s–1. What is the initial rate at 25 oC?

6. Rate = (5×107)[Cinit][Cinit]