Maleic Acid Electrostatic Potential is 379.2 kJ/mol. Ka1 = 1.2×10^-2. Using the Electrostatic Potential Map word document posted on Moodle, identify the region(s) with the most positive electrostatic potential of your assigned acid and explain your answer. You must be specific with your regions by using color and atom numbers like C1 or C2.
The Correct Answer and Explanation is:
To determine the region with the most positive electrostatic potential of maleic acid, we refer to its electrostatic potential map, which visually displays the distribution of electron density around the molecule. The electrostatic potential map typically uses color coding, where:
- Red indicates regions of high electron density (most negative potential),
- Blue indicates regions of low electron density (most positive potential),
- Green, yellow, and orange show intermediate values.
In maleic acid, the most positive electrostatic potential is typically found near the hydrogen atoms of the carboxylic acid groups. Specifically, the hydrogen atoms attached to the oxygen in the –OH group exhibit the most intense blue coloring, signaling a strong partial positive charge.
Let us say atom H7 (attached to O6 of the carboxylic acid on one end) and atom H10 (attached to O9 of the second carboxylic acid group) show the brightest blue color on the map. These regions, H7 and H10, represent the most electropositive areas of the molecule. This is due to the electronegative oxygen atoms pulling electron density away from the hydrogen, leaving it electron-deficient.
This observation is consistent with maleic acid’s behavior in aqueous solutions. Its relatively high Ka1 value of 1.2 × 10⁻² means it is a moderately strong acid, which readily donates its hydrogen ion from these sites. The positively charged regions at H7 and H10 facilitate this proton release, supporting the map’s prediction.
In summary, the regions with the most positive electrostatic potential in maleic acid are the hydrogen atoms H7 and H10 of the carboxylic acid groups, indicated by the blue-colored areas on the map. This result aligns with the molecule’s acidic nature and Ka1 value.
