1Week 9 CHEM 1310 - Sections L and M 1Ch 6: Chemical Equilibrium What is Equilibrium? Equilibrium Constant, K Equilibrium Expressions Involving Pressures Activity - read text Heterogeneous Equilibria Applications of Equilibrium Constant Solving Equilibrium Problems Le Chatelier’s Principle - very important Equilibria Involving Real Gases - read textWeek 9 CHEM 1310 - Sections L and M 2A system in equilibrium that is subjected to stressreacts in a way to counteract the stress.Le Châtelier’s Principle(1850-1936) Adding or RemovingReactants or Products Change in Volume orPressure of a System Change in TemperatureWeek 9 CHEM 1310 - Sections L and M 3Le Châtelier’s Principle What happens when reactants or products areadded to a system?Cu(H2O)42+ (aq) + 4 Cl- (aq) ↔ CuCl22- (aq) + 4 H2O (l)At equilibrium: blue-green colorAfter addition of HCl: solid greenAfter addition of H2O:2Week 9 CHEM 1310 - Sections L and M 4Le Châtelier’s Principle What happens when a reactants is removed froma system?Cu(H2O)42+ (aq) + 4 Cl- (aq) ↔ CuCl22- (aq) + 4 H2O (l)Ag+(aq) + Cl- (aq) ↔ AgCl(s)Ag+Result: See enhancement of blue colorShift from right to leftWeek 9 CHEM 1310 - Sections L and M 5Le Châtelier’s Principle What happens when the volume of thesystem is reduced?PCl5(g) ↔ PCl3(g) + Cl2(g)PV = nRTAs V↓ P↑Counteract pressure increase by shifting reaction toside where there are fewer molecules1 mole of reactants2 moles of productsWeek 9 CHEM 1310 - Sections L and M 6Le Châtelier’s Principle What happens when the temperature of thesystem changes?H2O (s) ↔ H2O (l)Adding energy (as heat) shifts equilibrium to rightMelting: endothermic (absorbs heat)Removing energy (i.e. putting ice in freezer) shifts equilibrium to leftFreezing: exothermic (liberates heat)3Week 9 CHEM 1310 - Sections L and M 7PRS Questions The equilibrium constant for A + 2B 3C is2.1 x 10-6. Determine the equilibriumconstant for 2A + 4B 6C.1. 4.2 x 10-62. 4.4 x 10-123. 2.3 x 10114. 1.8 x 10-115. None of theseWeek 9 CHEM 1310 - Sections L and M 8PRS Questions The equilibrium constant for A + 2B 3C is2.1 x 10-6. Determine the equilibriumconstant for 2A + 4B 6C.1. 4.2 x 10-62. 4.4 x 10-123. 2.3 x 10114. 1.8 x 10-115. None of theseWeek 9 CHEM 1310 - Sections L and M 9PRS Question Consider the following reaction2 HF(g) H2(g) + F2(g) K = 1.00 x 10-2)Given 1.00 mole HF, 0.500 mol H2 and 0.75 mol F2 aremixed in a 5.00-L flask, determine the reaction quotient, Q,and the net direction to achieve equilibrium.1. Q = 0.150; equilibrium shifts to the right2. Q = 0.375; equilibrium shifts to the left3. Q = 0.150; equilibrium shifts to the left4. Q = 0.375; equilibrium shifts to the right5. Q = 0.150; the system is at equilibrium4Week 9 CHEM 1310 - Sections L and M 10PRS Question Consider the following reaction2 HF(g) H2(g) + F2(g) K = 1.00 x 10-2)Given 1.00 mole HF, 0.500 mol H2 and 0.75 mol F2 aremixed in a 5.00-L flask, determine the reaction quotient, Q,and the net direction to achieve equilibrium.1. Q = 0.150; equilibrium shifts to the right2. Q = 0.375; equilibrium shifts to the left3. Q = 0.150; equilibrium shifts to the left4. Q = 0.375; equilibrium shifts to the right5. Q = 0.150; the system is at equilibriumWeek 9 CHEM 1310 - Sections L and M 11PRS Question To increase the value of K for the followingexothermic reaction, you must…2 Hs(g) + O2(g) H2O(g)1. Increase the total pressure2. Decrease the total pressure3. Increase the temperature4. Decrease the temperature5. Two of
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