Warm up # 101 1. Label each part of the graph. A. B. C. D. E. F. G. H. Endothermic Rxn Energy Reactants Activation energy Activated complex Change in energy Products Time 2. How do you know if this is endo or exothermic? The products are at a higher energy than the reactants

Factors Affecting Reaction Rates

Factors Affecting Reaction Rates There are several factors affect reaction rates Concentration Surface area (Particle size) Temperature Catalysts Inhibitors

Concentration

Surface Area Decreasing the particle size increases the amount of surface area where the reaction can take place, increasing the rate at which the reaction can occur Here the reaction between the solid magnesium metal and hydrogen ions can only happen at the surface

Increase in temp  increase in kinetic energy (more movement) more collisions  more reactants becoming products  increase in reaction rate

Catalysts A catalyst is a substance that increases the rate of a chemical reaction without itself being used up in the reaction. A catalysts provide an alternative energy pathway for the reaction. The different pathway lowers the activation energy allowing more molecules to overcome the activation energy and produce products at a faster rate

Potential Energy H A lower activation energy allows more molecules to overcome the activation energy, speeding up the reaction

Haber Process Fe/Al2O3/K2O catalyst N2 (g) + 3H2 (g) 2NH3 (g)

Remember that the catalase enzyme in your liver helps to break down H2O2 into water and O2.Enzymes lower the activation energy.

Inhibitor An inhibitor is a substance that slows down, or inhibits reaction rates. Uses A preservative A weed killer Asthma inhaler

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