© University of South Carolina Board of Trustees Chapt. 14 Chemical Equilibrium Sec. 4 Equilibrium Calculations

© University of South Carolina Board of Trustees Equilibrium Amounts  K eq At equilibrium, there are 2.50 mol H 2, 1.35 x10 -5 mol S 2, and 8.70 mol H 2 S in a 12.0 L flask. Calculate K c. 2 H 2(g) + S 2(g)  2 H 2 S (g)

© University of South Carolina Board of Trustees Initial Amounts  K eq A scientist places 1.0 mol of HI in a 10.0 L flask. Experiments show that the final, equilibrium concentration of I 2 is M. Find K c. 2 HI (g)  H 2(g) + I 2(g) iCe Table

© University of South Carolina Board of Trustees K c  Final Amounts A scientist adds 1.0 mol of H 2 and 1.0 mol of I 2 to a 1.0 L flask. Calculate the concentration of HI formed, given K c = HI (g)  H 2(g) + I 2(g) iCe Table

© University of South Carolina Board of Trustees Student Example A scientist adds 1.0 mol of H 2 and 3.0 mol of I 2 to a 2.0 L flask. Calculate the concentration of HI formed, given K c = HI (g)  H 2(g) + I 2(g) Set up the equation

© University of South Carolina Board of Trustees if Quadratic Formula then

© University of South Carolina Board of Trustees Student Example 2.3 mol of SO 2 and 1.6 mol of SO 2 Cl 2 are mixed in a 100 L flask. Calculate the equilibrium concentrations of all species if K c = 89.3 for SO 2(g) + Cl 2(g)  SO 2 Cl 2(g) Do it all

© University of South Carolina Board of Trustees Chapt. 14 Chemical Equilibrium Sec. 5 Special Rules

© University of South Carolina Board of Trustees The Rule The expression for K c (or K p ) does not contain terms for: ●Pure Solids ●Pure Liquids ●Solvents

© University of South Carolina Board of Trustees Write the expression for K eq for: 2 Hg (l) + Cl 2(g)  Hg 2 Cl 2(s) LiF (s)  Li + (aq) + F - (aq) Student Example K c = [Li + ] [F - ]