Kinetics Lesson 1

Kinetics & Equilibrium Kinetics - deals with the rate of chemical reactions and the mechanisms by which chemical reactions occur. Reaction Rate - a change in concentration per unit of time. Δ Concentration second Reactions of chlorine 5:33

Reaction Mechanism - a sequence of stepwise reactions by which the overall change occurs. 2NO(g) + F2(g)  2NOF(g)   Step 1: NO(g) + F2(g)  NOF2(g) Step 2: NOF2(g) + NO(g)  2NOF(g) NO(g) + F2(g) + NOF2(g) + NO(g)  NOF2(g) + 2NOF(g)   2 NO(g) + F2(g)  2NOF(g)

Kinetics & Equilibrium If molecules were people animation 04:45 Collision Theory - states that substances must collide in order to react. effective collision - collision leads to formation of products.   ineffective collision - collision does not lead to the formation of products. Orientation in a Chemical Reaction

Activated complex - a short lived transitional structure that is neither reactant nor product Activation Energy Ea - minimum energy needed to initiate a reaction Activation Energy narrated animation 01:16 Activation Energy Diagrams Heat of a Reaction (Enthalpy) - the heat energy released or absorbed in the reaction. ΔH = Hproducts - Hreactants Activation Energy narrated – Bozman Science 4:51

Kinetics & Equilibrium Endothermic reaction - energy is absorbed ΔH = + positive Exothermic reaction - energy is released Δ H = - negative

Factors Affecting Rate of Reaction Nature of Reactants - bonding (how strong are they bonded – ionic, covalent) - less rearrangement of atoms needed to form effective activated complex the faster the reaction (symmetry – polar, nonpolar)

Factors Affecting Rate of Reaction Nature of Reactants - bonding (how strong are they bonded – ionic, covalent) - less rearrangement of atoms needed to form effective activated complex the faster the reaction (symmetry – polar, nonpolar) - physical state (gases will react faster than solids) increased motion = increased collisions basically anything that increases the # of collisions will make the reaction happen faster

Factors Affecting Rate of Reaction Concentration - increase concentrations => increase the rate of reaction Concentration Rxn rate - increase concentrations => increase the frequency of collisions Concentration # collisions

Factors Affecting Rate of Reaction 3) Temperature - increase temperature => increase the rate of reaction Temperature Rxn rate - increase temperature => increase the kinetic energy KE => increase frequency of collisions Temperature KE # collisions

Factors Affecting Rate of Reaction 4) Surface Area - increase surface area => increase the frequency of collisions Surface Area # Collisions

Factors Affecting Rate of Reaction 4) Surface Area - increase surface area => increase the frequency of collisions Surface Area # Collisions

Factors Affecting Rate of Reaction 4) Surface Area - increase surface area => increase the frequency of collisions Surface Area # Collisions

Factors Affecting Rate of Reaction 5) Catalysts - changes the mechanism to one that involves less activation energy (lowers the activation energy) - increases the rate of the reaction without itself being used up in the reaction – just speeds up the reaction *Does not change the ∆H or the amount of product that is produced, it just makes it happen faster.   A + B → AB catalyst The 10 Most AMAZING Chemical Reactions (with Reactions) 13:09 Big Bang Theory Sheldon’s Revenge 02:48