Chemistry Chapter 12 – Quantitative Equilibrium Teacher: H. Michael Hayes

‘Learning Objectives’ You will learn the various factors related to equilibrium.

The Quantitative Aspect of Equilibrium The Equilibrium Constant: (K e ) is also called the equilibrium law. It is a relationship that shows that at a given temperature, in any simple chemical reaction at equilibrium, there is a constant ratio between product concentration and the reactant concentration, each concentration being raised to the power corresponding to the stoichiometric coefficient. Dynamic Equilibrium: in a system that is at chemical equilibrium, the direct reaction rate is equal to that of the reverse reaction rate.

The Quantitative Aspect of Equilibrium Expressing the Equilibrium Constant: according to rate law, the ratio of the reaction rate to the concentration of reactants, raised to the power corresponding to the stoichiometric coefficient of the balanced equation, is always constant at a given temperature.

The Quantitative Aspect of Equilibrium Expressing the Equilibrium Constant: according to rate law, the ratio of the reaction rate to the concentration of reactants, raised to the power corresponding to the stoichiometric coefficient of the balanced equation, is always constant at a given temperature.

The Quantitative Aspect of Equilibrium Expressing the Equilibrium Constant: according to rate law, the ratio of the reaction rate to the concentration of reactants, raised to the power corresponding to the stoichiometric coefficient of the balanced equation, is always constant at a given temperature.

The Quantitative Aspect of Equilibrium Expressing the Equilibrium Constant: according to rate law, the ratio of the reaction rate to the concentration of reactants, raised to the power corresponding to the stoichiometric coefficient of the balanced equation, is always constant at a given temperature.

The Equilibrium Constant The value of the equilibrium constant is calculated by using only the concentrations of gaseous substances or substances in solutions.

The Equilibrium Constant of the Reverse Reaction

The Equilibrium Constant Data List

The Equilibrium Constant

The Equilibrium Constant - Interpretation

The Equilibrium Constant – the effect of temperature The reaction is ENDOTHERMIC (- 566kJ on product side) Increasing Heat will drive the reaction to the Reactant Side to reduce added heat (Le Chatelier’s Principle at work!)

The Equilibrium Constant – ICE Table I – Initial Concentrations C – Change from Initial E – Equilibrium Concentrations Balanced Chemical Equation in Row 1

The Equilibrium Constant – ICE Table – Sample Problem 1.Data List 2.ICE TABLE

The Equilibrium Constant – ICE Table – Sample Prob ALWAYS – Organize and list the given and required DATA first!

The Equilibrium Constant – ICE Table – Sample Prob ALWAYS – Organize and list the given and required DATA first! Find the initial concentrations Moles divided by container volume

The Equilibrium Constant – ICE Table – Sample Prob ALWAYS – Organize and list the given and required DATA first! Find the initial concentrations Moles divided by container volume ICE Table A Calculate the change in concentration from given data. B Use Stoichiometry coefficients to calculate change of other Reactants and Products. C Subtract change from initial for C eq

The Equilibrium Constant – ICE Table – Sample Prob

1 – List and label given and unknown data 2 – Construct an ICE table 3 – Determine initial concentrations 4 – Determine change in concentrations using balanced equations 5 – Determine final concentrations

The Equilibrium Constant – ICE Table – Sample Prob 1 – List and label given and unknown data 2 – Construct an ICE table 3 – Determine initial concentrations 4 – Determine change in concentrations using balanced equations 5 – Determine final concentrations

The Equilibrium Constant – ICE Table – Sample Problem In this problem we use ‘x’ and ‘2x’ to represent the change in concentration since no numerical data is given. A B The equilibrium concentrations now become a function of x.

The Equilibrium Constant – Problem Practice! Do ALL the problems on pages 318 and 319 of your text – Practice Makes Perfect! Answer Keys are Posted on the Class Web Page.

The Equilibrium Constant – Ionic equilibrium in solutions Ionic equilibrium in solutions – a state of equilibrium established between the concentrations of the various ions following the dissociation of a chemical compound in a solution Salts in solution – Equilibrium Constant is expressed as K sp - Solubility Product Acids – Equilibrium Constant is K a Bases – Equilibrium Constant is K b Pure Water (H2O) – Equilibrium Constant is K water

The Equilibrium Constant – Part II Acid and Base Theory Arrhenius theory of acids and bases Bronsted-Lowry theory of acids and bases Ionization constant of water Calculating pH and pOH Salts in solution – Equilibrium Constant is expressed as K sp - Solubility Product Acids – Equilibrium Constant is K a Bases – Equilibrium Constant is K b Pure Water (H2O) – Equilibrium Constant is K water Determining Acidity and Basicity Constant – K a K b

Factors Affecting Reaction Rates End of Chapter 12 Onward to Chapter 13 Redox