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Chapter 12 Lecture Basic Chemistry Fourth Edition Chapter 12 Solutions 12.3 Solubility Learning Goal Define solubility; distinguish between an unsaturated and a saturated solution. Identify a salt as soluble or insoluble. © 2014 Pearson Education, Inc. Solubility Solubility • is the maximum amount of solute that dissolves in a specific amount of solvent • can be expressed as grams of solute per 100 grams of solvent, usually water © 2014 Pearson Education, Inc. Saturated Solutions Saturated Solutions • contain the maximum amount of solute that can dissolve • have undissolved solute at the bottom of the container • have equal rates at which the solute dissolves and crystallizes Solute dissolves Solute + Solvent Saturated Solution Solute recrystallizes © 2014 Pearson Education, Inc. Saturated, Unsaturated Solutions © 2014 Pearson Education, Inc. Solubility and Temperature Solubility • depends on temperature • increases as temperature increases for most solids • decreases as temperature increases for gases In water, most common solids are more soluble as the temperature increases. © 2014 Pearson Education, Inc. Learning Check At 40 C, the solubility of KBr is 80. g/100 g H2O. Identify the following solutions as either (S) saturated or (Un) unsaturated. A. 60. g of KBr added to 100. g of water at 40 C B. 200. g of KBr added to 200. g of water at 40 C C. 25 g of KBr added to 50. g of water at 40 C © 2014 Pearson Education, Inc. Solution At 40 C, the solubility of KBr is 80. g/100 g H2O. A. 60. g of KBr added to 100. g of water at 40 C Un, the amount of 60. g of KBr in 100. g of water, is less than the solubility of 80. g of KBr in 100. g of water. © 2014 Pearson Education, Inc. Solution At 40 C, the solubility of KBr is 80. g/100 g H2O. B. 200. g of KBr added to 200. g of water at 40 C S, in 100. g of water, 100. g of KBr exceeds the solubility of 80. g of KBr water at 40 C. © 2014 Pearson Education, Inc. Solution At 40 C, the solubility of KBr is 80. g/100 g H2O. C. 25 g of KBr added to 50. g of water at 40 C Un, this is the same as 50. g of KBr in 100. g of water, which is less than the solubility of 80. g of KBr in 100 g of water at 40 C. © 2014 Pearson Education, Inc. Solubility and Pressure Henry’s law states that • the solubility of a gas in a liquid is directly related to the pressure of that gas above the liquid • at higher pressures, more gas molecules dissolve in the liquid © 2014 Pearson Education, Inc. Solubility and Pressure, Henry’s Law When the pressure of a gas above the solution decreases, the solubility of that gas in the solution also decreases. © 2014 Pearson Education, Inc. Learning Check A. Why could a bottle of carbonated drink possibly burst (explode) when it is left out in the hot sun? A. Why do fish die in water that is too warm? © 2014 Pearson Education, Inc. Solution A. Why could a bottle of carbonated drink possibly burst (explode) when it is left out in the hot sun? The pressure in a bottle increases as the gas leaves solution, because it becomes less soluble at high temperatures. As pressure increases, the bottle could burst. © 2014 Pearson Education, Inc. Solution B. Why do fish die in water that is too warm? Because O2 gas is less soluble in warm water, fish cannot obtain the amount of O2 required for their survival. © 2014 Pearson Education, Inc. Soluble, Insoluble Ionic compounds that • dissolve in water are soluble salts • do not dissolve in water are insoluble salts © 2014 Pearson Education, Inc. Solubility Rules Soluble salts typically contain at least one ion from Groups 1A (1), NO3−, or C2H3O2− (acetate). © 2014 Pearson Education, Inc. Using Solubility Rules A barium sulfate-enhanced X-ray of the abdomen shows the large intestine. © 2014 Pearson Education, Inc. Learning Check Predict if the following compounds are soluble in water. A. Li3PO4 B. PbSO4 C. Ca(NO3)2 D. AgCl © 2014 Pearson Education, Inc. Solution Predict if the following compounds are soluble in water. A. Li3PO4 Soluble in water (Li+) B. PbSO4 Not soluble in water C. Ca(NO3)2 Soluble in water (NO3−) D. AgCl Not soluble in water © 2014 Pearson Education, Inc. Guide to Writing Equations for Insoluble Salt A chemical equation shows the complete formulas of all the compounds in a reaction. Pb(NO3)2(aq) + 2NaCl(aq) PbCl2(s) + 2NaNO3(aq) © 2014 Pearson Education, Inc. Guide to Writing Equations for Insoluble Salt An ionic equation shows all the ionic compounds as separate ions. Pb2+(aq) + 2NO3−(aq) + 2Na+(aq) + 2Cl−(aq) PbCl2(s) + 2Na+(aq) + 2NO3−(aq) A net ionic equation shows only the ions that react to form a solid. Pb2+(aq) + 2Cl−(aq) PbCl2(s) © 2014 Pearson Education, Inc. Guide to Writing Equations for Insoluble Salt © 2014 Pearson Education, Inc. Learning Check When solutions of AgNO3 and NaCl are mixed, a white solid forms. Write the ionic and net ionic equations for the reaction. © 2014 Pearson Education, Inc. Solution When solutions of AgNO3 and NaCl are mixed, a white solid forms. Write the ionic and net ionic equations for the reaction. Step 1 Write the ions of the reactants. Ag+(aq) + NO3−(aq) + Na+(aq) + Cl−(aq) © 2014 Pearson Education, Inc. Solution When solutions of AgNO3 and NaCl are mixed, a white solid forms. Write the ionic and net ionic equations for the reaction. Step 2 Write the combinations of ions and determine if any are insoluble. © 2014 Pearson Education, Inc. Solution When solutions of AgNO3 and NaCl are mixed, a white solid forms. Write the ionic and net ionic equations for the reaction. Step 3 Write the ionic equation including any solid. Ag+(aq) + NO3−(aq) + Na+(aq) + Cl−(aq) AgCl(s) + Na+(aq) + NO3−(aq) Ionic equation © 2014 Pearson Education, Inc. Solution When solutions of AgNO3 and NaCl are mixed, a white solid forms. Write the ionic and net ionic equations for the reaction. Step 4 Write the net ionic equation. © 2014 Pearson Education, Inc. Solution Ag+(aq) + Cl−(aq) © 2014 Pearson Education, Inc. AgCl(s) Net ionic equation