CHEM 104 1st Edition Lecture 13Chemical kinetics = study of rates of reactions and pathways/mechanisms from reactants to products Factors that influence reaction rates: - Concentration of reactants o Higher concentration higher rates - Temperature o Higher temperature higher rates - Catalystso Catalyst = substance that increases rate of reaction, but isn’t used up in the reaction (is also present after)- Surface of solid reactant or catalyst o Larger surface areas higher rates o Only applies to heterogeneous reactions Heterogeneous reactions = reactants are in different phasesHomogeneous reactions = reactants are in the same phase Reaction rate = change in concentration of a reactant or product per unit time Rate equation: change in concentration of product / change in time = - change of concentration of reactant / change in time - ‘Change in concentration of product’ = [product]- Need to take into account stoichiometry: aA + bBcC + dDRate: -1/a*[A]/change in time = -1/b*[B]/change in time = 1/c*[C]/change intime = 1/d*[D]/change in time Reactant product : graph below depicts reaction rates showing concentration of reactant over time (red) and concentration of product over time (blue)Average rate = rate over a time interval - Decreases over timeInstantaneous rate = rate at a single time point- Slope of the line tangent to the curve at time ‘t’Initial rate = instantaneous rate at
View Full Document
Unlocking...