you study the rate of a reaction, measuring both the concentration of the reactant and the concentration of the product as a function of time, and obtain the following results: time b a concentration (a) which chemical equation is consistent with these data: (i) a b, (ii) b a, (iii) a 2 b, (iv) b 2 a? (b) write equivalent expressions for the rate of the reaction in terms of the appearance or disappearance of the two substances. [section 14.2]