Experimental Determination of Reaction Order and Rate Constants

5 Experimental Determination of Reaction Order and Rate Constants 

Knowledge of the value of the rate of the reaction at different reactant concentrations would allow for determination of the rate and order of a chemical reaction. For the reaction A B, for example, reactant or product concentration-time curves are determined at different initial reactant concentrations. The absolute value of slope of the curve at t = 0, d[A]/dt)o or rf[B]/rft)o, corresponds to the initial rate or initial velocity of the reaction (Fig. 1.8). 

As shown before, the reaction velocity (ua) is related to reactant concentration, 

Taking logarithms on both sides of Eq. (1.42) results in the expression 

A plot of the logarithm of the initial rate against the logarithm of the initial reactant concentration yields a straight line with a y-intercept corresponding to log kr and a slope corresponding to n (Fig. 1.9). For more accurate determinations of the initial rate, changes in reactant concentration are measured over a small time period, where less than 1% conversion of reactant to product has taken place. 

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