Question

Question:How do you know that the absorption band at -1700cm^-1in figure 13.23 is due to a C-O bond and not a C-N bond.

Short answer

Answer

In the figure, it is due to C-O bond, as it is showing more intense absorption band.

Step-by-step solution

Difference betweem C-O bond and C-N bond

C-O bond is more polar compared to C-N bond.This is because of electronegativity difference in O and N. Oxygen is more electronegative than nitrogen.

Intense absorption band due to C-O bond

C-O bond is more polar so, they have large du/dx stretching vibrations to give intense peaks in this figure.C-N bonds is also showing absorption at, but the peaks are less intense compared to C-O Bond because of its low polar nature.

Hence, in the figure 13.23, the absorption band at 1700cm^-1 is due to C-O.