#9 Writing and Interpreting a Rate Law Expression
1. The gas phase reaction of nitric oxide and oxygen yieldsnitrogen dioxide:
2 NO (g)Â Â +Â Â O2 (g) ----> 2NO2 (g)
The rate law is rate = k[NO]2[O2].
a. What is the reaction order with respect to each reactant andwhat is the overall reaction order?
b. What are the units for k if time was expressed in units ofminutes?
c. If the concentration of NO was doubled and the concentrationof O2 was halved, what would happen to the rate?
d. If the NO was unchanged and the concentration ofO2 was doubled, what would happen to the rate?
e. If both of the reactants were tripled, what would happen tothe rate?
2. The reaction…
2 ICl (g)Â Â +Â Â H2 (g) ------>I2 (g)Â Â +Â Â 2 HCl (g)
is first order in H2 and first order in ICl. Writethe rate law expression and specify the units of the rate constant,k.
3. The reaction of CO and NO2 is second order withrespect to NO2 and zero order with respect to CO.
a. Write the rate law expression.
b. Expressing time in units of seconds, what are the units fork?
c. How does the reaction rate change if the CO concentration isdecreased by a factor of 5?
d. What is the change in the rate if the concentrations of bothreactants is doubled?
4. Using time units of hours, what would the units for k be fora reaction that is 1½ order?
5. For the following rate law…
           Rate = k[NO2]2[H2]
a. What is the order with respect to each reactant?
b. What is the overall order for the reaction?
c. What are the units for the rate constant, k, if the time unitis seconds?
d. What would happen to the rate if each reactant wasquadrupled?
e. What would happen to the rate if NO2 was unchangedand the H2 was halved?
