Consider the balanced equation for the decomposition of ozone:

2O3(g) 3O2(g)

Can the rate law for this chemical reaction be deduced from its balanced equation?

A)Yes; since the reactant and product are both oxygen gases, the reaction takes 0 seconds.

B)Yes; the coefficients of the balanced equation determine the order of the reaction.

C)No; the rate law must be determined experimentally.

D)No; the rate will change randomly.

C)No; the rate law must be determined experimentally.

Explanation:

Rate Laws are empirical relationships defining rates of reaction. For any given reaction The Empirical Rate Law is the product of the concentration of the reactants raised to the power of their order of reaction. That is, for the hypothetical reaction aA + bB => Products its Empirical Rate Law is ...

Rate = k[A]ᵃ[B]ᵇ where k = the rate constant and a & b are orders of reaction.

Order of reaction is a 'rate trend' when one changes a rate factor such as concentration. This can only be determined by experimental observation by physically increasing or decreasing concentration and observing the change in reaction rate relative to a reference reaction of interest. Typically they are whole numbers but can be decimal fractions.  

By graphing experimental outcomes of Rxn Rate vs Change in Concentration one can define the order of reaction. Observations  give ...

0-order reactions => change concentration => no change in rate

1st order reactions => change concentration => proportional linear change in rate

2nd order reactions => change concentration => exponential change in rate.        

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.