University:
The University Of Western Ontario
Course:
2223B | Organic Chemistry of Biological Molecules
Academic year:

2023
Views:

297

Pages:

2
Author:

Cole M

Solubility Equilibria Common Polyatomic Ions: Memorize these common polyatomic ions → Dissolution & Precipitation: Hydration is when an ion is surrounded and stabilized by a shell of the solvent molecules Can also be said to form a solvation shell Precipitate is when a solid forms in a solvent and is the opposite of dissolution This occurs if electrostatic forces between the ions is greater than that of hydration (between water molecules and the ions) Spectator ions are ions that do not participate in the reaction (exists as a reactant and a product in the reaction scheme) Introduction to Solubility & Solubility Product Constant: There are many ionic compounds that are only partially soluble in water Saturated solution is once the max amount of solute has dissolved into solution and the rest simply falls to the bottom Solubility is the amount of solute is able to dissolve per liter of solution (can be shown as g/L or mol/L (M)) Solubility product constant (Ksp) is simply another type of equilibrium constant You can use an ICE table in order to figure out the Ksp for a given dissolution reaction (use changes in molarities not moles) and make sure to pay attention to coefficients (you can always ignore the number if it is being added/subtracted from x) Remember, for K you do NOT include solids or liquids The Ksp is determined by what was dissolved in solution, not the part that wasn’t Solubility from the Solubility Product Constant: Can also do an ICE table, but this time use x in order to show the amount that was lost and/or gained ← If you keep going, you can find the final concentrations of OH- and Cu2+ Can convert backwards from molarity if needed Solubility & the Common Ion Effect: Common ion effect refers to the decrease in solubility of an ionic precipitate by the addition to the solution of a soluble compound with an ion in common with what is already dissolved in the solution (such as in this video where it decreased from 0.016M in pure water to 0.0016M in a solution with KCl already dissolved in it) The equilibrium shifted to the left (since there was already some product present) Solubility & the pH of the Solution: You can increase/decrease solubility of a solute by adjusting the pH An example of this could be with the reaction to the right, where [H+] was increased and therefore reacted with F- ions, pushing the reaction to the right You need to make sure the base is strong enough in order to react with the extra H+ ions present in solution Solubility & Complex Ion Formation: Need to use net reactions in order to compare solubility constants when you add in an extra ions into solution In order to find equilibrium constants from two separate reactions, multiply them together Extra Notes: CASH-N-GIA is a mnemonic for solubility rules. Chlorates, Acetates, Sulfates, Halides (not Fluorides), Nitrates, Group I metals, Ammonium. These compounds are generally soluble (anything not included here can be considered insoluble) Exception include: exceptions include Hg22+, Ag+, and Pb2+ (HAPpy) and CBS from group II metals (Ca2+, Ba2+, and Sr2+) Gases dissolving in liquid is an exothermic reaction Remember, only F, O, and N can hydrogen bond