ChemChapter4Notes - Chapter 4 - Types of Chemical Reactions...

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Chapter 4 - Types of Chemical Reactions and Solution Chemistry 4.1 Water, the Common Solvent - the water molecule is bent with and H-O-H angles of approx. 105 º - O-H bonds are covalent - O is slightly negative; H is slightly positive - polar molecules - the solvation of salts by H 2 O is called hydration (break up into constituent ions) - ionic bond is replaced by dipole-ion interaction - hydrated ions are written with a subscript (aq) in a reaction eq. - nonionic substances can also dissolve in H 2 O, ex. ethanol - “like dissolves like” 4.2 The Nature of Aqueous Solutions: Strong and Weak Electrolytes - solute – a substance dissolved in a liquid to form a solution - solvent – the dissolving medium in a solution 1) weak electrolytes - conduct a small amount of current 1a. - weak acids & bases (most common) 1b. - only about 1% ionizes 1c. - weak acids and bases only slightly ionize 2) strong electrolytes - conduct current very efficiently 2a. - completely ionize (soluble salts, strong acids, strong bases) 2b. - Arrhenius proposed that acid produce H+ ions 2c. - (aq) subscript is used 2d. - strong acids completely ionize (H 2 SO 4 , HNO 3 , HCl, HClO 4 ) 2e. - strong bases completely ionize (NaOH, KOH) 3) nonelectrolytes - don’t allow current to flow 3a. - do not produce ions 4.3 The Composition of Solutions molarity (M) = moles of solute liters of solution *Sample exercise 4.2, 4.3, & 4.4 Exercise 4.2: Calculate the molarity of a solution prepared by dissolving 1.56 g of gaseous HCl in enough water to make 26.8 mL of solution. Since molarity is a combination of moles and liters, we have to get those two units. We can get moles by multiplying grams by the molar mass. Liters can be found with the mL and
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dimensional analysis. Finally, divide these two terms to get molarity. 1.56 g HCl x 1 mol = 4.28 x 10 -2 mol 36.46 g 26.8 mL x 1 L = 2.68 x 10 -2 L 1000 mL Molarity = 4.28 x 10 -2 mol = 1.60 M HCl 2.68 x 10 –2 L standard solution - solution with known concentration 4.4 Types of Chemical Reactions 1) Precipitations reactions
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This note was uploaded on 09/27/2010 for the course CHEM 210 taught by Professor Mcomber during the Spring '10 term at Skyline College.

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ChemChapter4Notes - Chapter 4 - Types of Chemical Reactions...

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