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Section 15.1 Forming Solutions 1.To understand the process of dissolving 2.To learn why certain substances dissolve in water 3.To learn qualitative terms describing the concentration of a solution 4.To understand the factors that affect the rate at which a solid dissolves Objectives
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Section 15.1 Forming Solutions What is a solution? Solution – homogeneous mixture –Solvent – substance present in largest amount –Solutes – other substances in the solution –Aqueous solution – solution with water as the solvent
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Section 15.1 Forming Solutions
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Section 15.1 Forming Solutions A. Solubility Solubility of Ionic Substances Ionic substances breakup into individual cations and anions.
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Section 15.1 Forming Solutions A. Solubility Solubility of Ionic Substances Polar water molecules interact with the positive and negative ions of a salt.
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Section 15.1 Forming Solutions A. Solubility Solubility of Polar Substances Ethanol is soluble in water because of the polar OH bond.
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Section 15.1 Forming Solutions A. Solubility Solubility of Polar Substances Why is solid sugar soluble in water?
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Section 15.1 Forming Solutions A. Solubility Substances Insoluble in Water Nonpolar oil does not interact with polar water. Water-water hydrogen bonds keep the water from mixing with the nonpolar molecules.
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Section 15.1 Forming Solutions A. Solubility How Substances Dissolve A “hole” must be made in the water structure for each solute particle. The lost water-water interactions must be replaced by water-solute interactions. “like dissolves like”
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Section 15.1 Forming Solutions B. Solution Composition: An Introduction The solubility of a solute is limited. –Saturated solution – contains as much solute as will dissolve at that temperature –Unsaturated solution – has not reached the limit of solute that will dissolve
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Section 15.1 Forming Solutions B. Solution Composition: An Introduction –Supersaturated solution – occurs when a solution is saturated at an elevated temperature and then allowed to cool but all of the solid remains dissolved Contains more dissolved solid than a saturated solution at that temperature Unstable – adding a crystal causes precipitation
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Section 15.1 Forming Solutions B. Solution Composition: An Introduction Solutions are mixtures. Amounts of substances can vary in different solutions. –Specify the amounts of solvent and solutes –Qualitative measures of concentration concentrated – relatively large amount of solute dilute – relatively small amount of solute
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Section 15.1 Forming Solutions B. Solution Composition: An Introduction Which solution is more concentrated?
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Section 15.1 Forming Solutions B. Solution Composition: An Introduction Which solution is more concentrated?
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Section 15.1 Forming Solutions C. Factors Affecting the Rate of Dissolving Surface area Stirring Temperature
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Section 15.2 Describing Solution Composition 1. To understand mass percent and how to calculate it 2. To understand and use molarity 3. To learn to calculate the concentration of a solution made by diluting a stock solution Objectives
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Section 15.2 Describing Solution Composition A. Solution Composition: Mass Percent
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Section 15.2 Describing Solution Composition B. Solution Composition: Molarity Concentration of a solution is the amount of solute in a given volume of solution.
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Section 15.2 Describing Solution Composition B. Solution Composition: Molarity Consider both the amount of solute and the volume to find concentration.
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Section 15.2 Describing Solution Composition B. Solution Composition: Molarity To find the moles of solute in a given volume of solution of known molarity use the definition of molarity.
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Section 15.2 Describing Solution Composition B. Solution Composition: Molarity Standard solution - a solution whose concentration is accurately known To make a standard solution –Weigh out a sample of solute. –Transfer to a volumetric flask. –Add enough solvent to mark on flask.
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Section 15.2 Describing Solution Composition C. Dilution Water can be added to an aqueous solution to dilute the solution to a lower concentration. Only water is added in the dilution – the amount of solute is the same in both the original and final solution.
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Section 15.2 Describing Solution Composition D. Dilution Diluting a solution –Transfer a measured amount of original solution to a flask containing some water. –Add water to the flask to the mark (with swirling) and mix by inverting the flask.
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Section 15.3 Properties of Solutions 1.To learn to solve stoichiometric problems involving solution reactions 2.To do calculations involving acid-base reactions 3.To learn about normality and equivalent weight 4.To use normality in stoichiometric calculations 5.To understand the effect of a solute on solution properties Objectives
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Section 15.3 Properties of Solutions A. Stoichiometry of Solution Reactions
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Section 15.3 Properties of Solutions B. Neutralization Reactions An acid-base reaction is called a neutralization reaction. Steps to solve these problems are the same as before.
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Section 15.3 Properties of Solutions C. Normality Unit of concentration –One equivalent of acid – amount of acid that furnishes 1 mol of H + ions –One equivalent of base – amount of base that furnishes 1 mol of OH ions –Equivalent weight – mass in grams of 1 equivalent of acid or base
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Section 15.3 Properties of Solutions C. Normality
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Section 15.3 Properties of Solutions C. Normality
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Section 15.3 Properties of Solutions C. Normality To find number of equivalents
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Section 15.3 Properties of Solutions C. Normality Advantage of equivalents
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Section 15.3 Properties of Solutions D. Boiling Point and Freezing Point The presence of solute “particles” causes the liquid range to become wider. –Boiling point increases –Freezing point decreases
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Section 15.3 Properties of Solutions D. Boiling Point and Freezing Point Why does the boiling point of a solution increase? –Solute particles block some of the water molecules trying to enter the bubble. –Need higher pressure to maintain the bubble. –Forming a bubble in a solution
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Section 15.3 Properties of Solutions D. Boiling Point and Freezing Point –Comparing bubbles
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Section 15.3 Properties of Solutions D. Boiling Point and Freezing Point Colligative property – a solution property that depends on the number of solute particles present
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