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homogeneous throughout - same phase. All of them are mixtures but not all mixtures are solutions



dissolved or dispersed in a solvent



component of solution that remains in the same phase after mixing, in which solute is dissolved; if already in same phase as solute, the solvent is that which is present in greater quantity



the electrostatic interaction between solute and solvent molecules; also called dissolution; when water is solvent called hydration


when solvation is exothermic

when new interactions between molecules are stronger than the original ones; favored at low temps


when solvation is endothermic

when the new interactions formed are weaker than the original ones; favored at high temps; most dissolutions are this


ideal solution

enthalpy of dissolution is equal to zero; solutions get close to this when overall strength of new interactions is approximately equal to overall strength of original interactions


entropy of dissolution

second property (along with enthalpy) that contributes to whether a dissolution is spontaneous or not - at constant temp and pressure, entropy always increases upon dissolution


solubility of a substance

the max amount of that substance that can be dissolved in a particular solvent at a given temp


saturated solution

when the max amount of solute has been added and the dissolved solute is in equilibrium with its undissolved state


if more solute is added to an already saturated solution

solute will not dissolve but precipitate to the bottom


dilute solution

solution in which proportion of solute to solvent is small ; still unsaturated


concentrated solution

solution in which proportion of solute to solvent is large; still unsaturated


when is a solute considered soluble

when Gibbs free energy is negative and reaction will proceed spontaneously


sparingly soluble salts

those solutes that dissolve minimally in a solvent (molar solubility under 0.1 M)


aqueous solution

solvent is water


hydronium ion



solubility rules for aqueous solutions (know rules one and two)

1. All salts containing ammonium (NH4)+ and alkali metal (group 1) cations are water-soluble; 2. all salts containing nitrate (NO3)- and acetate (CH3COO-) anions are water-soluble; 3. Halides (Cl-, Br-, I-) except fluorides, are water soluble except those formed with Ag+, Pb2+, and (Hg2)2+; 4. All salts of sulfate ion (SO4)2- are water soluble, except those formed with Ca2+, Sr2+, Ba2+, and Pb2+; 5. all metal oxides are insoluble except ones formed with alkali metals, ammonium, and CaO, SrO, and BaO; 6. all hydroxides are insoluble except ones formed with alkali metals, ammonium, and Ca2+, Sr2+, and Ba2+; 7. all carbonates (CO3)2+, phosphates (PO4)3-, sulfides S2-, and sulfites (SO3)2- are insoluble except ones formed with alkali metals and ammonium


complex ion - or coordination compound

refers to a molecule in which a cation is bonded to at least one electron pair donor (which could include the water molecule) [complexation reactions]



electron pair donor molecules


coordinate covalent bonds

bonds that hold complexes together, in which an electron pair donor (a Lewis base) and an electron pair acceptor (a Lewis acid) form very stable Lewis acid-base adducts



central cation of a complex is bonded to the same ligand in multiple places; usually requires large organic ligands that can double back to form second or third bond with the central cation



denotes the amount of solute dissolved in a solvent


percent composition by mass

mass of solute/mass of solution x 100


mole fraction (X)

XsubA = moles of A/total moles of all species; used to calculate the vapor pressure depression of a solution


molarity (M)

M = moles of solute/liters of solution


molality (m)

m = moles of solute/kilograms of solvent; for dilute aqueous solutions at 25 degrees C, the molality is approx equal to molarity because the density of water at this temp is 1 kg per L. situations where it is required are boiling point elevation and freezing point depression


normality (N)

equal to the number of equivalents of interest per liter of solution; equivalent is measure of the reactive capacity of a molecule (equal to a mole of the species of interest); how many moles of electrons an ion will accept in a certain solution


equation for concentration of solution after dilution

M sub i (V sub i) = M sub f (V sub f); M = molarity, V = volume and subscripts i and f = initial and final values


saturation point

in process of creating a solution, this is the equilibrium, where the solute concentration is at its max value for the given temp and pressure; rates of dissolution and precipitation are equal, and concentration of dissolved solute reaches a steady state (constant) value; neither is favored thermodynamically