Chem 1465 1st Edition Lecture 15Outline of Last Lecture 1. Concepts to understand for the testA. Lewis dot structureB. VSEPR shapes C. Unit cell calculationsD. Calculate the amount of work doneE. Calculate heatOutline of Current Lecture 1. Intro to chemical equilibrium2. Equilibrium constants3. Gas phase equilibria: Kp and Kc4. Homogenous and heterogeneous equilibria 5. Variations in the form of the reaction and K6. ICE tableCurrent Lecture1. Intro to chemical equilibrium- Up to this point we have assumed that chemical reactions go to completion but this is not always true. - Dynamic equilibrium: for a chemical reaction it is the condition in which the rate of the forward reaction is equals the rate of the reverse reaction. - Rate laws: rateforward = Kforward [R], raterev = Krev[P], Kfor [R] = Krev[P]2. Equilibrium constant- Law of mass action: based on the relationship of the concentration and lots of data. For this reaction: aA + bB → cC + dD - Define the ration of concentrations: Q = ( [C]c [D]d ) / ( [A]a [B]b ) where q is the reaction quotient and lower case means the coefficients - When the reaction is equilibrium Q becomes K; K= ( [C]ceq [D]deq ) / ( [A]aeq [B]beq )These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.3. Gas phase equilibria: Kp and Kc - For gases it is easier to measure pressure than concentration. PV=nRT but we canrearrange to solve for concentration (n/v) such that (P/rT)=(n/v)- Using pressure: Kp = (PC PD)/(PA PB)- Using the idea gas law: Kp = Kc (RT)Δn4. Homogeneous and heterogeneous equilibrium- Homogeneous equilibrium: all reactants and products are in the same phase- Heterogeneous equilibrium: reactants and products are not all in the same phase- We include molecules in the gas or aqueous phase. We do not include molecules in the solid or liquid phase.- If K is much much smaller than 1 then the reactants are favored in the reaction and little products are formed. - If K is equal to 1 then roughly half and half reactants and products are formed.- If K is much much bigger than 1 then the products are favored int eh reaction andthere is little reactants. 5. Variations in the form of the reaction and K- If the reaction is reversed, then invert K- If the reaction is multiplied by n, then raise K to the factor of n- If the reactions are added, then multiply the K’s together- K has no units6. ICE tables- I: initial concentrations- C: change in concentrations based on coefficients- E: equilibrium
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