Mr Quinn Ms Tom March 18 2014 Aim

Mr. Quinn & Ms. Tom March 18, 2014 Aim: What is a chemical equilibrium? Do Now: Define “homeostasis, ” and provide an example

Introduction Homeostasis is a type of EQUILIBRIUM Dynamic equilibrium: products and reactants have constant concentrations over time, despite continuously reacting

Introduction • If molecules can “jump” one way, they can often jump the other. • Activation energy has to be LOW in BOTH directions. • The forward reaction goes left to right • The reverse reaction goes right to left

Introduction What does that look like?

Are we still together? In a dynamic equilibrium, which of the following must be true? 1. A catalyst is present 2. The rates of the forward and reverse reactions are equal 3. No reaction is taking place 4. Heat is released

Let’s try it out! In order to perform calculations with equilibrium, we need to be able to identify reactants for each reaction: Forward Reaction Reverse Reaction

Let’s try it out! In order to perform calculations with equilibrium, we need to be able to identify reactants for each reaction:

Let’s try it out! In order to perform calculations with equilibrium, we need to be able to identify reactants for each reaction:

Are we still together? Consider the following balanced chemical equation: A + B ⇌ C How many reactants does the REVERSE reaction have? 1. 2. 3. 4. 1 2 3 4

Your Turn!

Your Turn! A system is said to be in a state of dynamic equilibrium when the 1. concentration of products is greater than the concentration of reactants 2. concentration of products is the same as the concentration of reactants 3. rate at which products are formed is greater than the rate at which reactants are formed 4. rate at which products are formed is the same as the rate at which reactants are formed

Your Turn! Which reaction would have the lowest activation energy? 1. the forward catalyzed reaction 2. the forward uncatalyzed reaction 3. the reverse catalyzed reaction 4. the reverse uncatalyzed reaction

Your Turn! In the diagram below, which letter represents the activation energy for the reverse reaction? 1. A 2. B 3. C 4. D

Your Turn! In a reversible reaction, chemical equilibrium is attained when the 1. rate of the forward reaction is greater than the rate of the reverse reaction 2. rate of the reverse reaction is greater than the rate of the forward reaction 3. concentration of the reactants reaches zero 4. concentration of the products remains constant

Your Turn! A beaker contains 100. 0 milliliters of a dilute aqueous solution of ethanoic acid at equilibrium. The equation below represents this system. HC 2 H 3 O 2 (aq) ↔H+ (aq) + C 2 H 3 O 2– (aq) Compare the rate of the forward reaction to the rate of the reverse reaction for this system.