Lesson 1.2 Factors Affecting Rate PDF

Unit #1: What determines chemical change? Lesson 2: Factors affecting rate YOSRA SAAD 1  MYP5 Chemistry Unit #1: What determines chemical change? Key Concept Change Related Concepts Transfer, Movement Global Conte...

Unit #1: What determines chemical change? Lesson 2: Factors affecting rate YOSRA SAAD 1  MYP5 Chemistry Unit #1: What determines chemical change? Key Concept Change Related Concepts Transfer, Movement Global Context Orientation in time and space Physical and chemical changes require the transfer of kinetic Statement of energy between particles of matter over time, affecting the Inquiry space they occupy. YOSRA SAAD 2 Think About It How can I make sugar dissolve faster in a cup of water? Are there any other factors that can increase reaction rate? YOSRA SAAD 3 Factors Affecting Rate of Reaction YOSRA SAAD 4 Reactivity and Reaction Rates Some substances react more readily than others. Ex. 1. Reactivity series for metals and non-metals. 2. Covalent vs. Ionic reactants 3. Gas vs. liquid or solid reactants Concentration and Reaction rates Increasing concentration of reactants leads to increase in reaction rate. Explain using the collision theory. When concentrations are increased, more molecules are available to collide per unit volume, and therefore collisions occur more frequently. Surface Area and Reaction Rates For the same mass, many small particles have more surface area than one large particle. Reaction rate increases with increasing surface area. Explain using the collision theory: Greater surface area allows particles to collide with many more particles per unit of time. Temperature and Reaction Rates Increasing temperature generally increases reaction rate. For every 10K increase in temperature, rate is doubled. Maxwell-Boltzmann Energy Distribution Curve Key points: 1. No particles have zero energy 2. Most particles have intermediate energies 3. A few particles have very high energies indeed 4. The average energy is not the same as the most probable energy YOSRA SAAD 9 Temperature and Reaction Rates Explain using the collision theory: Increasing temperature increases the kinetic energy of the particles. Reacting particles collide more frequently at higher temperatures. High-energy collisions are more frequent at a higher temperature. As temperature increases, reaction rate increases. Catalysts and Inhibitors A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the reaction. An inhibitor is a substance that slows or prevents a reaction. Example: preservatives Why Do Catalysts Speed up Rate? Catalysts lower the activation energy. Low activation energy means that more of the collisions between particles will have sufficient energy to overcome the activation energy barrier and bring about a reaction.