The overall order of an elementary step directly corresponds to its molecularity. Both steps in this example are second order because they are each bimolecular. Furthermore, the rate law can be determined directly from the number of each type of molecule in an elementary step. For example, the rate law for step 1 is

rate=k[NO]^2

The exponent "2" is used because the reaction involves twoNO^2 molecules. The rate law for step 2 is

rate=k[N_2O_4]^1[CO]^1=k[N_2O_4][CO ]

because the reaction involves only one molecule of each reactant the exponents are ommitted.

Analyzing a new reaction Consider the following elementary steps that make up the mechanism of a certain reaction: 1.3A>B+C 2. B+2D>C+F

A. What is the overall reaction? Express your answer as a chemical equation.

B. Which species is a reaction intermediate?

C. What is the rate law for step 1 of this reaction? Express your answer in standard MasteringChemistry notation. For example, if the rate law is type k*[A]*[C]^3.

D. What is the rate law for step 2 of this reaction? Express your answer in standard MasteringChemistry notation. For example, if the rate law is type k*[A]*[C]^3.

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.