Hydrolsis of Sucrose

Chemistry 102 - Experiment 5 Chemical Kinetics: The Acid-Catalyzed Hydrolysis of Sucrose
INTRODUCTION

Chemical kinetics involves the determination of the velocity or rate of a chemical reaction. The rate of a reaction depends on the nature of the reactants, the concentration of the reactants, the temperature, and the presence of catalysts. The effect of the concentration of various species on the reaction rate is summarized by a general equation called the rate law for the reaction. The effect of temperature on the reaction rate leads to conclusions regarding the energy required for a reaction. An analysis of all the kinetic data can result in the determination of a mechanism or path by which the reaction proceeds. Thermodynamics involves the determination of whether or not a reaction is spontaneous and only considers the initial reactant and final product states of a system. Thermodynamics and kinetics are thus complimentary.

The first step in studying the kinetics of a system is to determine the rate law for the reaction. The rate law for any reaction must be determined experimentally. It cannot be deduced from the overall chemical equation and there is often no simple relation between the form of the net balanced chemical equation and the rate law. Sometimes the rate equation takes on a simple form but often the rate is found to be a complex function of various reactant and product concentrations. Consider the general reaction aA + bB → Products (1)

where A and B represent chemical formulas, and a and b their stoichiometric coefficients. If the rate law for reaction (1) is found to depend simply on the concentration of A and B, the rate law would have the form Rate = k [A]n[B]m (2)

The square brackets, [ ], indicate concentration in moles/liter; the proportionality constant, k, is termed the rate constant; and the exponents, n and m, are called the order of the reaction. If n = 1 and m = 2, the reaction is first order with respect to A, second order with...