Wright CHM 1220 - CHM 1220 SI_Chemical Equilibrium_Rev 2_ANSWERS (2 pages)

Previewing page 1 of 2 page document View the full content.
View Full Document

CHM 1220 SI_Chemical Equilibrium_Rev 2_ANSWERS



Previewing page 1 of actual document.

View the full content.
View Full Document
View Full Document

CHM 1220 SI_Chemical Equilibrium_Rev 2_ANSWERS

27 views


Pages:
2
School:
Wright State University
Course:
Chm 1220 - General Chemistry II

Unformatted text preview:

Questions Comments Suggestions Email me at stevens 161 wright edu Chapter 14 SI Activity Chemical Equilibrium ANSWERS CHM 1220 Problems 1 The equilibrium constant Kp for the reaction PCl5 g PCl3 g Cl2 g is 3 81 102 at 600 K and 2 69 103 at 700 K Without doing any calculations predict whether this reaction is endothermic or exothermic Since the reaction becomes increasingly product favored as the temperature increases the reaction must be endothermic by Le Ch tlier s principle We can imagine heat as a reactant for endothermic reactions so heating the reaction vessel would be like adding reactant which forces the reaction toward the right Verify your answer in part by calculating the change in enthalpy Need to find H for rxn given two Ks and two Ts K H 1 1 ln 2 R T2 T1 K1 1 1 K R ln 2 H T2 T1 K1 1 H 1 K 1 1 2 69 103 1 1 R ln 2 8 31447 molJ K ln 68 3 2 3 81 10 700 K 600 K K1 T2 T1 kJ mol Predict how the equilibrium would shift under the following stresses i an increase in volume ii addition of an inert gas and iii addition of a catalyst i Rxn shifts toward side with more molecules of gas to fill the available space ii Adding inert gas i iii Shifts Right Products No effect increases the pressure which causes the rxn to shift toward the side with fewer moles of gas iii Catalysts affect the rates of the forward and reverse rxns equally so there is no net effect on the equilibrium ii Shifts Left Reactants Calculate Kc for the reaction at 600 K Use relationship between Kc and Kp K p K c RT n K c K p RT n 3 81 102 0 082057 L atm mol K 600 K 2 1 7 73824 7 74 If the initial concentrations of the species are PCl5 0 500 M PCl3 0 150 M and Cl2 0 600 at 600 K in which direction does the reaction proceed toward equilibrium What are the equilibrium Use values from ICE table in equilibrium expression concentrations PCl3 Cl2 0 600 x 0 150 x Need Q before determining rxn direction Kc PCl5 0 500 x PCl3 Cl2 0 600 M 0 150 M 0 180 Q Rewrite expression as a standard form quadratic eqn PCl5 0 500 M K c 0 500 x 0 600 x 0 150 x Comparing Q to K 3 869 7 738 x 0 0900 0 750 x x 2 Since Q 0 180 is smaller than K 7 74 the rxn will proceed to the right products Then need ICE table to find concentrations I C E PCl5 g PCl3 g Cl2 g 0 500 M 0 150 M 0 600 M x x x 0 500 x 0 150 x 0 600 x 0 3 779 8 488 x x



View Full Document

Access the best Study Guides, Lecture Notes and Practice Exams

Loading Unlocking...
Login

Join to view CHM 1220 SI_Chemical Equilibrium_Rev 2_ANSWERS and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view CHM 1220 SI_Chemical Equilibrium_Rev 2_ANSWERS and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?