Create Presentation
Download Presentation

Download Presentation
## Notes handout, equilibrium video part 2

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -

**Le Châtelier’s Principle**Le Chatelier’s Principle: if you disturb an equilibrium, it will shift to undo the disturbance. Remember, in a system at equilibrium, Keq is a constant. 3 Common ways to disturb an equilibrium:**Le Châtelier’s Principle**• Effect of Temperature Changes • The equilibrium constant is temperature dependent. • For an endothermic reaction, heat can be considered as a reactant. • For an exothermic reaction, heat can be considered as a product. • Adding heat causes the reaction to shift to get rid of this extra heat**Effect of Temp. Change**N2 + O2 2NO ΔHrxn= +180.5kJ What is effect of increasing T?**Effect of Change in Concentration**For reaction Butane Isobutane Kc at 25oC = 2.50 What would be the effect of adding 1.5 M butane?**Common Ion Effect**• At equilibrium the conc. of butane is 0.2M and Isobutane is 0.5M. If 2.00 mol / L isobutane is added, what will the new equilibrium concentrations be?**Effect of Volume Change in Gas Phase Equilibrium**In reactions involving gases, if you change the size of the container, you will also change the gas concentration. The effect of a volume decrease would be to shift the equilibrium to the side with the fewer numbers of gas molecules**In the reaction:**2NO2 N2O4 Kc = 170 at 298K What would be the effect of halving the volume of the container?**Solubility Equilibria**The solubilities of slightly soluble compounds can be written as equilibrium expressions. Write the equilibrium expression for the dissolving of silver bromide: Since the reactant is solid, only the products (ions) are involved in the Ksp expression Ksp (solubility product constant):**Ksp Values**• Ksp values can be found on charts of Ksp constants at a given temperature • Relative solubilities of compounds can be compared IF the ion ratios in the two compounds are the same, but not if they’re different. • Compare solubilities of: AgCl and AgI • Compare solubilities of: Ca(OH)2 and CaSO4**Solubility Product Calculations**Write the equilibrium expression for the dissolving of calcium fluoride: If the solubility of CaF2 is 2.4 x 10-4 mol/L at 25°C, find the Ksp**Solubility Product Calculations**The Ksp for barium sulfate is 1.1 x 10-10. Find the solubility in mol/L and g/L.**The Ksp for magnesium fluoride is 5.2 x 10-11. Find the**solubility in mol/L.**Common Ion Effect: when an ion common to the equilibrium is**added, it affects the equilibrium balance. If you add AgCl to 1.0L of 0.55M NaCl, what mass of AgCl will dissolve? The Ksp of AgCl = 1.8 x 10-10**The Ksp for AgCl is 1.8 x 10-10. If the concentration of**silver ions is 1.2 x 10-5, is the solution saturated, or will more dissolve?**The concentration of magnesium ions in solution is 1.5 x**10-6. If NaOH is added to make the hydroxide concentration 1.0 x 10-4, will Mg(OH)2 precipitate form? The Ksp for Mg(OH)2 is 5.6 x 10-12.**A solution of 100.0 mL of 0.0010M AgNO3 is prepared. Will**AgCl precipitate if 5.0 mL of 0.025M HCl are added?