1. 6-4

2. 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

3. 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.

4. 2 HI H 2 I2I2 initial2.00 change equil.214 0 0 2(.214).214 1.57.214 subtract reactants add products - + +

5. Use equilibrium numbers

6. 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 ?

7. N2N2 3 H 2 2NH 3 initial0.320.66 change equil0.30 0 0.12 0.36.24 0.20.24 subtract reactants add products - + -

9. Ex: At a particular temperature, keq for the H 2 (g) + I 2 (g) 2HI (g) has a value of 55.6. 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.

10. H2H2 I 2 2HI initial0.200 change equil 0 x x 2x 0.20-x 2x subtract reactants add products - + - 0.20-x

13. Question was [HI] at equilibrium: 2x 2(0.1577) = 0.315 M

14. Equilibrium sheet: 1-9 Assigment: p 587 # 24 – 27. p 588 # 42 Answers: 24)a. 0.76 b.0.52; c: 310 25) 1.4 x 10 10 26) 110. M 27) 0.0250 42) 5.6 x 10 -9 M