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Chemistry 30 – Unit 2 – Solubility – Ch. 16 in Text. 06 – using a solubility TABLE & SOLUBILITY CURVES. Saturated, Unsaturated & Supersaturated Solutions. Saturated solution: Contains the maximum amount of solute for a given amount of solvent at a constant temperature
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Chemistry 30 – Unit 2 – Solubility – Ch. 16 in Text 06 – using a solubility TABLE & SOLUBILITY CURVES
Saturated, Unsaturated & Supersaturated Solutions • Saturated solution: • 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
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 • 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?