06 – using a solubility TABLE & SOLUBILITY CURVES Chemistry 30 – Unit 2 – Solubility – Ch. 16 in Text

Saturated, Unsaturated & Supersaturated Solutions Contains the maximum amount of solute for a given amount of solvent at a constant temperature The rate of dissolving and crystallization are equal You can NOT add more solute without it forming a crystallized solid Unsaturated solution: Contains less solute than a saturated solution You can still add more solute without a crystallized solid forming Supersaturated solution: Contains more solute than it can theoretically hold at a given temperature There is a noticeable amount of crystallized solid formed

Saturated Solution

Unsaturated Solution

Supersaturated Solution

Solubility Curves A solubility curve is a graph that shows us what mass of a solute will make a saturated solution in 100 g (or 100 mL) of water over a range of temperatures. In general, the solubility of liquids and solids increase with temperature (there are few exceptions). We will read the graph to determine the solubility of specific compounds at given temperatures.

Solubility Curves

Solubility Curves Ex) How much KClO3 will dissolve in water at 30˚ C? What about at 80˚ C? Ex) What substance has a solubility of 102 g/100 mL of water at 60˚ C? Ex) How many moles of NaNO3 are in 1.00 L of water if the solution is saturated at 25.0˚ C?

Solubility Curves Values that are below the curve means the solution is unsaturated (more solute can be dissolved). Likewise, values above the curve represent supersaturation (more solute than can be dissolved is present).

Solubility Curves Ex) Describe the solution in terms of saturation for the following: a) 70 g of NaNO3 per 100 mL of H2O at 30˚ C. b) 60 g of KCl per 100 mL of H2O at 80˚ C. c) 80 g of KNO3 per 100 mL of H2O at 50˚ C.

Solubility Table A solubility table tells us whether or not an ionic compound will dissolve in water at a specific temperature (usually 25.0˚ C). It gives you a list of common cations and anions and indicates if the resulting ionic compound is soluble in water i.e. – Chloride anion (Cl-) when combined with the following cations (Ag+, Pb2+, Hg22+, Cu+) will NOT be soluble; however, with all other cations it, WILL be soluble

Solubility Table “Soluble” indicates that the ionic compound is soluble in water at 25oC “Low solubility” indicates that the ionic compound is not soluble in water at 25oC Low solubility indicates that a precipitate will form in the resulting solution

Solubility Table In general, you need to find a specific ion from your formula on the chart and see if the ion it is paired up with will produce a soluble substance. Ex) is (NH4)2SO4 soluble in water? Ex) is PbI2 soluble in water?