Do Now Answer the riddle: What comes down but never goes up? When the bell rings After the bell (2 min) Answer the riddle: What comes down but never goes up? In your seat: With pen/pencil With Notebook With Handout Silent and ready for Do Now Still needs Do Now

Agenda  Do Now (5 min) Warm Up: (20 min) Notes: Equilibrium (30 min) Group Practice (10 min) Independent Practice (15 min) Exit Slip (5 min) Closeout (2 min)  Agenda

Unit: Thermodynamics Topic: Equilibrium Objectives: Explain what it means for a reaction to be at equilibrium Predict how changes in temperature, pressure and concentration will affect equilibrium

Mood rings use changes in blood circulation to change color Mood rings use changes in blood circulation to change color. How is this an example of equilibrium? Guiding question

A reaction is spontaneous when: If a reaction feels hot or cold, is this an open or closed system? Explain. Warm Up (20 min) A reaction is spontaneous when: ∆H (energy) = - ∆S (disorder) = +

A reaction is spontaneous when: Would the following reaction occur spontaneously? I do: Ca(s) + S(s)  CaS(s) + energy Warm Up (20 min) A reaction is spontaneous when: ∆H (energy) = - ∆S (disorder) = +

A reaction is spontaneous when: Would the following reaction occur spontaneously? We do: CaS(s) + heat Ca(s) + S(s) Warm Up (20 min) A reaction is spontaneous when: ∆H (energy) = - ∆S (disorder) = +

A reaction is spontaneous when: Would the following reaction occur spontaneously? We do: 20kJ + H2O(s)  H2O(l) Warm Up (20 min) A reaction is spontaneous when: ∆H (energy) = - ∆S (disorder) = +

A reaction is spontaneous when: Would the following reaction occur spontaneously? We do: H2O(l)  H2O(s) + 20kJ Warm Up (20 min) A reaction is spontaneous when: ∆H (energy) = - ∆S (disorder) = +

A reaction is spontaneous when: Would the following reactions occur spontaneously? You do: F2(g) + 2Li(s)  2LiF(s)+ energy NaCl(s) + energy  NaCl(l) Warm Up (20 min) A reaction is spontaneous when: ∆H (energy) = - ∆S (disorder) = +

Vocabulary and Definitions Equilibrium: a condition that exists when the forward reaction rate equals the reverse reaction rate such that there appears to be no change in the concentration of products or reactants. Le Chatelier’s Principle: if equilibrium is disturbed by changing conditions, the position of equilibrium shifts to reestablish an equilibrium Vocabulary and Definitions

KP #1: What is dynamic equilibrium? In every reaction we have talked about this year, we said Reactants  Products We call this the forward reaction KP #1: What is dynamic equilibrium? REACTANTS PRODUCTS

KP #1: What is dynamic equilibrium? But…Sometimes under the right circumstances Reactants  Products We call this the reverse reaction KP #1: What is dynamic equilibrium? REACTANTS PRODUCTS

KP #1: What is dynamic equilibrium? When this happens, both reactions occur simultaneously (at the same time) KP #1: What is dynamic equilibrium? REACTANTS PRODUCTS

KP #1: What is dynamic equilibrium? When the rate (pace) of the forward reaction equals the rate of the reverse reaction we call this DYNAMIC EQUILIBRIUM In other words, reactants make products (forward) at the same speed as the products make reactants (reverse) KP #1: What is dynamic equilibrium?

KP #1: What is dynamic equilibrium? Represented by: KP #1: What is dynamic equilibrium? OR

KP #1: What is dynamic equilibrium? Water Wars Two volunteers What to watch for: What happens to the water levels over time Was there a time when it seemed the levels did not change? KP #1: What is dynamic equilibrium?

KP #2: Le Chatelier’s Principle Equilibrium can shift Which means: One direction of the reaction is favored (occurs faster) 3 Factors: Concentration (amount) Temperature Pressure KP #2: Le Chatelier’s Principle OR

KP #3: Predicting changes Concentration: amount of products/reactants can be added or removed Away from: the side that is increased Towards: the side that is decreased KP #3: Predicting changes H2O2 H2 + O2

KP #3: Predicting changes Temperature: Can be increased or decreased Away from: the side with energy or heat when temp Towards: the side with energy or heat when temp KP #3: Predicting changes H2O2 + energy H2 + O2

KP #3: Predicting changes Pressure: Can be increased or decreased Away from: side with most gas molecules when pressure Towards: side with most gas molecules when pressure KP #3: Predicting changes H2O2(g) H2(g) + O2(g) 1 1 1 2 gas molecules

KP #3: Predicting changes 4 Steps Identify the factor that changes and circle it in the equation Draw an arrow to show how it changes ( ) Determine the shift and draw the favored direction Answer the questions arrow pointing at = increase arrow pointing away = decrease KP #3: Predicting changes H2O2 H2 + O2 Copy steps under your warm up

KP #3: Predicting changes I do: If the concentration of H2O2 is increased, which direction will the equilibrium shift? What will happen to the concentration of H2 over time? KP #3: Predicting changes H2O2 H2 + O2

KP #3: Predicting changes We do: If the concentration of O2 is increased, which direction will the equilibrium shift? What will happen to the concentration of H2O2 over time? What about H2? KP #3: Predicting changes H2O2 H2 + O2

KP #3: Predicting changes You do: If the concentration of H2O2 is decreased, which direction will the equilibrium shift? What will happen to the concentration of H2 over time? KP #3: Predicting changes H2O2 H2 + O2

KP #3: Predicting changes You do: If the concentration of O2 is decreased, which direction will the equilibrium shift? What will happen to the concentration of H2O2 over time? What about H2? KP #3: Predicting changes H2O2 H2 + O2

KP #3: Predicting changes I do: If the temperature is increased during the reaction to the right, which direction will equilibrium shift? What will happen to the concentration of H2O2? What about H2? KP #3: Predicting changes H2O2 + energy H2 + O2

KP #3: Predicting changes You do: If the temperature is decreased during the reaction to the right, which direction will equilibrium shift? What will happen to the concentration of H2O2? What about H2? KP #3: Predicting changes H2O2 + energy H2 + O2

KP #3: Predicting changes I do: If the pressure is increased during the reaction to the right, which direction will equilibrium shift? What will happen to the concentration of H2O2? What about H2? KP #3: Predicting changes H2O2(g) H2(g) + O2(g) 1 1 1 2 gas molecules

KP #3: Predicting changes You do: If the pressure is decreased during the reaction to the right, which direction will equilibrium shift? What will happen to the concentration of H2O2? What about H2? KP #3: Predicting changes H2O2(g) H2(g) + O2(g) 1 1 1 2 gas molecules

Small Group Practice How What 10 minutes Complete practice on handout C: 1 - 2, on task conversation H: Ask partners, raise hand, move on to next question until I am available A: Completing questions M: In clusters. 3 Hall passes. P: Answering questions on handout, using notes, head up, discussing in groups, using boxes 10 minutes Complete practice on handout

Independent Practice How What 15 minutes C: 0 – 1, only on task conversation H: Raise hand, move on to next question until I am available A: Completing questions M: In clusters. 3 Hall passes. P: Answering questions on notebook paper, using notes, head up, discussing in groups, using boxes 15 minutes Complete practice on reverse side of notes

Exit Slip 2K + S  K2S + Heat If heat is added, which direction will equilibrium shift? What will happen to the amount of K2S over time? What will happen to the amount of S over time? Exit Slip Answers on scrap paper 3 minutes No notes No conversation