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Which Bulbs Light Up? Bulb Wattage 7.5 25 Based on the results of the experiment, which one of the following is a weak electrolyte? 40 Distilled H2O a) Distilled H2O Tap H2O b) NaCl(aq) NaCl(aq) c) 1M HCl(aq) 1M HCl(aq) d) 1M CH3COOH 1M CH3COOH e) sugar(aq) sugar(aq) f) CH3OH CH3OH • For bulb to light, some minimum amount of current is needed. • amount of current is related to the CONDUCTIVITY of the solution. CONDUCTIVITY: ability to conduct electricity Identifying an electrolyte Electrolytes • Strong – completely ionized (in solution) Good conductors − NaCl(s) + H2O → Na+(aq) + Cl (aq) + H2O B) If it is molecular, is it an acid or a base? Yes: it is a strong or weak electrolyte No: it is a non electrolyte. − HCl(aq) + H2O → H3O +(aq) + Cl (aq) • Weak – partially ionized (in solution) Poor conductors − NH3(aq) + H2O ↔ NH4+(aq) + OH (aq) CH3COOH(aq)+H2O ↔ CH3COO−(aq)+H3O (aq) + • Nonelectrolytes – not ionized in solution Non-conductors C6H12O6(s)+H2O → C6H12O6(aq)+ H2O glucose A) Is the compound ionic or molecular? Ionic: it is a strong electrolyte Note: it could be insoluble Molecular ??? Examples of electrolytes (strong or weak) Acids donate H+(aq) Bases accept H+(aq) Salts formed by replacing one or more H+ of an acid with another cation Examples of non-electrolytes: Alcohols Carbohydrates (sugar) Aldehydes, ketones Difference between strong and weak electrolytes Assume all salts are strong electrolytes. Memorize strong acids and bases (Table 4.2) If a compound is an acid or a base, but NOT one of the strong acids or bases, then it MUST be a weak electrolyte. These are all water soluble compounds. Are they strong, weak or non electrolytes? Use Flowchart HCl NaCl CH3OH Common misconception: Electrolytes are ionic compounds CH3COOH (acetic acid) NOT TRUE NH3 • Strong electrolytes – ionic or molecular compounds that ionize completely in solution. Fe(NO3)2 Ca(OH)2 • Weak electrolytes– molecular compounds that are partially ionized in solution. • Nonelectrolytes – molecular compounds that do not ionize in solution Water soluble Compound molecular ionic Is it an acid? Yes No Is it a strong acid? Yes Strong electrolyte Is it a molecular base? (eg. NH3) no yes Strong Electrolyte no weak electrolyte weak electrolyte non electrolyte