Stearate, electrostatic potential map

FIGURE 19 5 Electrostatic potential map of sodium stearate Most of the molecule is comprised of a nonpolar hydrocarbon chain (green) One end is very polar as indicated by the red and blue associated with the carboxylate and sodium ions respectively... 

Stearate ion contains two very different str-uctural units—a long nonpolar- hydrocarbon chain and a polar- carboxylate group. The electrostatic potential map of sodium stearate in Figure 19.5 illustrates how different most of the molecule is from its polar- carboxyl-ate end. 

Compare and contrast the electrostatic potential map of a typical detergent with that of a typical soap (stearate). Which part of each molecule will be most water soluble (hydrophilic) Draw a Lewis structure that describes each molecule s water-soluble group (make sure you indicate all necessary formal charges and lone pairs). Which part(s) of each molecule will be most grease soluble (lipophilic) What kinds of atoms and bonds are found in these groups ... 

Electrostatic potential map for stearate shows negatively-charged regions (in red) as well as neutral regions (in green). 

Compare the electrostatic potential maps of sodium lauryl sulfate and sodium stearate on Learning By Modeling. 

The structure of (a) sodium stearate and (b) an electrostatic potential map of the stearate anion that illustrates the polar nature of the carboxylate ion and nonpolar nature of the hydrocarbon chain. 

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