Subject: Organic Chemistry · Chapter: Organic Spectroscopy · Topic: IR · Exam: CSIR-NET DEC 2019 · Marks: 2 · Difficulty: Medium
The frequency of O-H stretch occurs at $3600\,\mathrm{cm}^{-1}$. The O-D stretch frequency (in $\mathrm{cm}^{-1}$) would be closest to
(a)3000
(b)2600
(c)1800
(d)900
Answer
Answer (as printed): B
Explanation
$\nu_{\mathrm{O-H}} = 3600\,\mathrm{cm}^{-1}$Since $\nu = \dfrac{1}{2\pi c}\sqrt{\dfrac{k}{\mu}}$, frequency is inversely proportional to the square root of $\mu$ (the reduced mass).This gives $\nu_{\mathrm{O-D}} \approx 2600\,\mathrm{cm}^{-1}$