UNIT 8: KINETICS & EQUILIBRIUM Lecture 1: Collision Theory

Do Now  Fill out the ‘Do Now’ on your ‘Do Now and Self- Evaluation’ sheet for the week A 5.96 g sample of calcium completed reacted with oxygen to form 8.60 grams of calcium oxide. Determine the total mass of oxygen reacted. Show all work. 2Ca + O 2  2CaO Answer: 2.64 g Reason: The Law of Conservation of Mass The total mass of reactants and products in a chemical reaction must be equal

What? How? Why?  What: I can recognize how the movement of atoms and molecules affects the rate at which chemical reactions occur.  How:  Do Now: TCAP Prep  Unit Intro: so we know where we are going in the next month  Lecture: so we can understand the new vocabulary being used  Video: so we can see what chemical reactions look like if it were a video game  Reaction Rate table activity  Why:  So we can understand why the movement of atoms makes explosions happen, cooking work, and cars go.

Weekly Agenda  Monday – Intro to Unit 8: Kinetics!  Tuesday – Kinetics!  Wednesday – Field Trip/Mastery Day  Thursday – Field Trip/Mastery Day  Friday – Field Trip/Mastery Day

Catalyzing Thoughts: Think Pair Share  What does it take to hit a homerun?  The ball has to be thrown hard enough  The ball has to be thrown far enough  The batter has to hit the ball hard enough  The batter has to hit the ball at the right time

Kinetics: Vocabulary  Activation Energy: The amount of energy needed to activate atoms/molecules to undergo a chemical reaction  Effective Collision: a collision between two reactants with the correct orientation (direction) and enough energy to start a chemical reaction

Watch. Listen. Learn   Write down 3 things you learned about collision theory from the video.  You must ‘hit’ the target in the right place  You must hit the target with the right amount of energy  You must hit the target enough times

Collision Theory  Collision Theory: A chemical reaction occurs ONLY when an EFFECTIVE COLLISION occurs. This happens under two conditions: WHEN THE REACTANTS COLLIDE WITH … 1. The same or more energy than the activation energy (hit ‘em hard enough) 1. The correct orientation (hit ‘em in the right place)

Reaction Rate  REACTION RATE: The speed of a reaction (how FAST or SLOW a reaction occurs)  Write down 3 things that you think might speed up a chemical reaction

Reaction Rate Predictions  Look at the table in your guided notes  predict whether the reaction rate will increase, decrease or remain the same for each scenario

Do Now  Complete the Do Now on your Do Now and Daily Evaluation sheet  Draw a graph to show how temperature effects the rate of reaction for a chemical reaction

What? How? Why?  What: I can understand how the movement of atoms and molecules affects the rate at which chemical reactions occur  How  Do Now  Factors affecting reaction rate table  Guided Practice  Why: So we can understand why the movement of atoms makes explosions happen, cooking work, and cars go

Weekly Agenda  Monday – Kinetics  Tuesday – Kinetics  Wednesday – Mastery/Field Trip  Thursday – Mastery/Field Trip  Friday - Kinetics

Factors Affecting Reaction Rate  Include information about these trends in the table on the back of your guided notes

Identity of Compound  Ionic compounds react faster because ions separate in aqueous solutions easily  Reactions between covalent compounds take place slowly because they require energy to break bonds

Catalyst: Increases Reaction Rate  Catalyst: a substance which speeds up a reaction, but is chemically unchanged at the end of the reaction.  Catalysts speed up a reaction because they lower the activation energy required for a chemical reaction to occur

Surface Area: Increases Reaction Rate

Pressure: Increases Reaction Rate

Temperature: Increases Reaction Rate  When molecules are hot, they move quickly. The more quickly molecules move, the more likely they are to collide with other molecules and start a chemical reaction

Concentration: Increases Reaction Rate  The higher the concentration of reactants, the more particles there are. When you have more particles they are more likely to collide and start a chemical reaction

Kinetics: Guided Practice 1. In order for a chemical reaction to occur, there must always be a. An effective collision between reacting particles b. A bond that breaks in a reactant particle c. Reacting particles with a high charge d. Reacting particles with high kinetic energy EEffective Collision: reactants (atoms/molecules) hit one another in the right place, and with enough energy (= > activation energy)

Kinetics: Guided Practice AAs the number of effective collisions between reacting particles increases, the rate of reaction 1. Decreases 2. Increases 3. Remains the same 4. Changes the orientation of the particles

Kinetics: Guided Practice IIn a chemical reaction, as the concentrations of the reacting particles increase, the rate of reactions generally 1. Decreases 2. Increases 3. Remains the same 4. Reaches equilibrium

Kinetics: Guided Practice WWhich conditions will increase the rate of a chemical reaction? 1. Decreased temperature and decreased concentration of reactants 2. Decreased temperature and increased concentration of reactants 3. Increased temperature and decreased concentration of reactants 4. Increased temperature and increased concentration of reactants

Kinetics: Guided Practice EExplain why a crushed solid reacts with a gas more quickly than a large chunk of the same solid IIncreased surface area increases the number of collisions between molecules

 Apply collision theory to explain why foods usually spoil more slowly when refrigerated than at room temperature.  The temperature is lower so molecules move more slowly. If molecules move more slowly they are less likely to collide

Kinetics: Guided Practices  In each of the four beakers shown below, a 2.0-cm strip of magnesium ribbon reacts with 100 ml of HCl (aq) under the conditions shown. (M = how strong something is). In which beaker will the reaction occur at the fastest rate? Beaker D Higher Concentration and higher temperature will lead to more effective collisions between reactants

Collision Theory Independent Classwork and Homework  Answer questions 1 – 5 using your guided notes and guided practice.  Underline all the important words in a question