Define “rate,” OR give an example of a rate Mr. Quinn & Ms. Tom March 13, 2014 Aim: What influences the rate of a chemical reaction? Do Now: Define “rate,” OR give an example of a rate

Introduction In order to react, molecules must: Collide With enough energy In the proper orientation

The effect of Temperature on Rate of Reaction Let’s Try It Out! The effect of Temperature on Rate of Reaction As temperature increases, rate of reaction increases. As temperature decreases, rate of reaction decreases. Temperature affects the energy of the particles. Temperature Time to Dissolve Cold   Room Temperature Hot

The effect of Surface Area on Rate of Reaction Let’s Try It Out! The effect of Surface Area on Rate of Reaction As surface area increases, rate of reaction increases. As surface area decreases, rate of reaction decreases. Surface area affects the number of collisions of the particles. Surface Area Time to Melt Low (solid)   High (crushed)

The effect of Pressure on Rate of Reaction Let’s Try It Out! The effect of Pressure on Rate of Reaction As pressure increases, rate of reaction increases. As pressure decreases, rate of reaction decreases. Pressure affects the number of collisions of the particles. Pressure Product Formed Low   Medium High

Your Turn!

Your Turn! What is required for a chemical reaction to occur? standard temperature and pressure a catalyst added to the reaction system effective collisions between reactant particles an equal number of moles of reactants and products

Your Turn! As the temperature of a chemical reaction in the gas phase is increased, the rate of the reaction increases because fewer particle collisions occur more effective particle collisions occur the required activation energy increases the concentration of the reactants increases

Your Turn! Why can an increase in temperature lead to more effective collisions between reactant particles and an increase in the rate of a chemical reaction? The activation energy of the reaction increases. The activation energy of the reaction decreases. The number of molecules with sufficient energy to react increases. The number of molecules with sufficient energy to react decreases.

Your Turn! As the number of effective collisions between reacting particles increases, the rate of reaction Decreases Increases remains the same

Your Turn! At STP, which 4.0-gram zinc sample will react fastest with dilute hydrochloric acid? Lump Bar Powdered sheet metal

Your Turn! Given the reaction: Mg + 2 H2O → Mg(OH)2 + H2 At which temperature will the reaction occur at the greatest rate? 25°C 50°C 75°C 100°C

Your Turn! Oxygen reacts with the surface of a solid zinc sample. Provide TWO methods for increasing the rate of this reaction. Increase the temperature Increase the surface area