Kinetics 0.0 / 5 ? ChemistryKineticsA2/A-levelAQA Created by: r98Created on: 19-03-16 12:34 What are the main factors that affect the rate of reactions? Temperature, concentration, pressure, surface area and catalysts. 1 of 17 What's the definition of rate of reaction? The change in concentration (of any of the reactants or products) with unit time. 2 of 17 How do you find the rate at a particular instant? Draw a tangent to the curve at that time and then find its gradient (slope). 3 of 17 Why do we have to keep the temperature constant when measuring rate of reaction? Because rate varies with temperature. 4 of 17 What are the units of reaction rates? mol dm-3 s-1 5 of 17 Can a species thats not in the chemical equation appear in the rate equation? Yes, for example a catalyst. 6 of 17 Is the rate constant, k, different for every reaction? Yes. 7 of 17 What does k vary with? Temperature. 8 of 17 What happens when all the species in the rate equation are 1 mol dm-3? The rate of reaction is equal to the value of k. 9 of 17 What's the order of reaction? The order of reaction, with respect to one species, is the power to which the concentration of that species is raised in the rate expression. 10 of 17 What does the order of reaction tell you? How the rate depends on the concentration of that species. 11 of 17 Do all species in the chemical equation appear in the rate equation? No, not necessarily. 12 of 17 Do the coefficience of species in the chemical equation have any importance in the rate expression? No, they have no relevance. 13 of 17 What are the units of the rate constant, k? The units of the rate constant vary depending on the overall order of the reaction. 14 of 17 Increasing temperature always increases what two things? The rate of reaction & the value of the rate constant, k. 15 of 17 Do steps that occur after the rate-determining step affect the rate? No, provided that it's fast compared with the rate-determining step. 16 of 17 Do species that are involved in the mechanism after the rate-determining step appear in the rate expression? No, only species involved in or before the rate-determining step could affect the overall rate and therefore appear in the rate expression. 17 of 17
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