Chapter 4 - CHAPTER 4 REACTIONS IN AQUEOUS SOLUTIONS 4.7...

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CHAPTER 4 REACTIONS IN AQUEOUS SOLUTIONS 4.7 (a) is a strong electrolyte. The compound dissociates completely into ions in solution. (b) is a nonelectrolyte. The compound dissolves in water, but the molecules remain intact. (c) is a weak electrolyte. A small amount of the compound dissociates into ions in water. 4.8 When NaCl dissolves in water it dissociates into Na + and Cl ions. When the ions are hydrated, the water molecules will be oriented so that the negative end of the water dipole interacts with the positive sodium ion, and the positive end of the water dipole interacts with the negative chloride ion. The negative end of the water dipole is near the oxygen atom, and the positive end of the water dipole is near the hydrogen atoms. The diagram that best represents the hydration of NaCl when dissolved in water is choice (c) . 4.9 Ionic compounds, strong acids, and strong bases (metal hydroxides) are strong electrolytes (completely broken up into ions of the compound). Weak acids and weak bases are weak electrolytes. Molecular substances other than acids or bases are nonelectrolytes. (a) very weak electrolyte (b) strong electrolyte (ionic compound) (c) strong electrolyte (strong acid) (d) weak electrolyte (weak acid) (e) nonelectrolyte (molecular compound - neither acid nor base) 4.10 Ionic compounds, strong acids, and strong bases (metal hydroxides) are strong electrolytes (completely broken up into ions of the compound). Weak acids and weak bases are weak electrolytes. Molecular substances other than acids or bases are nonelectrolytes. (a) strong electrolyte (ionic) (b) nonelectrolyte (c) weak electrolyte (weak base) (d) strong electrolyte (strong base) 4.11 Since solutions must be electrically neutral, any flow of positive species (cations) must be balanced by the flow of negative species (anions). Therefore, the correct answer is (d) . 4.12 (a) Solid NaCl does not conduct. The ions are locked in a rigid lattice structure. (b) Molten NaCl conducts. The ions can move around in the liquid state. (c) Aqueous NaCl conducts. NaCl dissociates completely to Na + ( aq ) and Cl ( aq ) in water. 4.13 Measure the conductance to see if the solution carries an electrical current. If the solution is conducting, then you can determine whether the solution is a strong or weak electrolyte by comparing its conductance with that of a known strong electrolyte. 4.14 Since HCl dissolved in water conducts electricity, then HCl( aq ) must actually exists as H + ( aq ) cations and Cl ( aq ) anions. Since HCl dissolved in benzene solvent does not conduct electricity, then we must assume that the HCl molecules in benzene solvent do not ionize, but rather exist as un-ionized molecules. 4.17 Refer to Table 4.2 of the text to solve this problem. AgCl is insoluble in water. It will precipitate from solution. NaNO 3 is soluble in water and will remain as Na + and NO 3 ions in solution. Diagram (c) best represents the mixture.
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CHAPTER 4: REACTIONS IN AQUEOUS SOLUTIONS 61 4.18 Refer to Table 4.2 of the text to solve this problem. Mg(OH) 2 is insoluble in water. It will precipitate from solution.
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Chapter 4 - CHAPTER 4 REACTIONS IN AQUEOUS SOLUTIONS 4.7...

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