Problem: Dissolution in water. (a) When an ionic compound, such as sodium chloride, NaCl, dissolves in water, H2O molecules separate, surround, and uniformly disperse the ions into the liquid. (b) Molecular substances that dissolve in water, such as methanol, CH3OH, usually do so without forming ions. We can think of this as a simple mixing of two molecular species. In both (a) and (b) the water molecules have been moved apart so that the solute particles can be seen clearly.Which solution, NaCl(aq) or CH3OH(aq), conducts electricity?

FREE Expert Solution

Recall that electrolytes are solutions that conduct electricity


• Strong electrolytes: dissociate completely in water; include soluble ionic salts/compounds, strong acids, and bases


• Weak electrolytes: doesn’t dissociate completely in water; include weak acids and bases


• Nonelectrolytes: doesn’t dissociate at all; include molecular compounds


  • NaCl → soluble ionic compound (Group 1A salt)  strong electrolyte
    • dissociates completely into ions: NaCl → Na+ + Cl- 
  • CH3OH → molecular compound  non-electrolyte


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Problem Details

a) Ionic compounds like sodium chloride, NaCl, form ions when they dissolve.  A diagram shows water molecules and a cube made of alternating sodium and chloride ions. 1) H2O molecules separate Na+ and Cl- ions from solid NaCl. 2) H2O molecules surround Na+ and Cl- ions.  The water molecules are arranged so that the hydrogens associate with Cl- and the oxygens associated with Na+. 3) Na+ and Cl- ions disperse throughout the solution. b) Molecular substances like methanol, CH3OH, dissolve without forming ions.  Diagram shows water molecules and methanol molecules in solution.

Dissolution in water. (a) When an ionic compound, such as sodium chloride, NaCl, dissolves in water, H2O molecules separate, surround, and uniformly disperse the ions into the liquid. (b) Molecular substances that dissolve in water, such as methanol, CH3OH, usually do so without forming ions. We can think of this as a simple mixing of two molecular species. In both (a) and (b) the water molecules have been moved apart so that the solute particles can be seen clearly.

Which solution, NaCl(aq) or CH3OH(aq), conducts electricity?

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