6-4
Steps for solving equilibrium problems: 1. Write out the equation. 2. Balance the equation if it is not. 3. Make a chart. (ICEBOX) I – initial C – change E - equilibrium
e.g. What is the equilibrium constant for the reaction of HI (g) H 2 (g) + I 2 (g) when the initial concentration of HI is 2.00M and the [I 2 ] at equilibrium is 0.214M. Balance the reaction.
2 HI H 2 I2I2 initial2.00 change equil (.214) subtract reactants add products - + +
Use equilibrium numbers
Ex: for the reaction: N 2 (g) + 3H 2 (g) 2NH 3 (g) The initial [N 2 ] = 0.32 M and [H 2 ] = 0.66 M. At a certain temperature and pressure the equilibrium [H 2 ] is found to be 0.30M. What is the value of keq ?
N2N2 3 H 2 2NH 3 initial change equil subtract reactants add products - + -
Ex: At a particular temperature, keq for the H 2 (g) + I 2 (g) 2HI (g) has a value of If the initial [H 2 ] = 0.200M and the initial [I 2 ] = 0.200M, what is the equilibrium [HI]? If Keq is given and no other information, you will have x as your change.
H2H2 I 2 2HI initial0.200 change equil 0 x x 2x 0.20-x 2x subtract reactants add products x
Question was [HI] at equilibrium: 2x 2(0.1577) = M
Equilibrium sheet: 1-9 Assigment: p 587 # 24 – 27. p 588 # 42 Answers: 24)a b.0.52; c: ) 1.4 x ) 110. M 27) ) 5.6 x M