Chemistry

Catherine E. Housecroft, Edwin C. Constable

ISBN #9780273715450

4th Edition

995 Questions

13,222 Students Helped

Homework Questions

Summary

Learning Objectives

Key Concepts

Example Problems

Explanations

Common Mistakes

Summary

Spectroscopy is an essential analytical technique that reveals the interactions between light and matter. By understanding the principles behind absorption and emission spectra, scientists can determine the composition, structure, and properties of substances across various disciplines—from astronomy to chemical engineering. The ability to distinguish between different spectral lines enables precise identification and analysis, making spectroscopy a powerful tool in both research and industrial applications.

Learning Objectives

Key Concepts

CONCEPT

DEFINITION

Acyclic and cyclic alkanes

A discussion of both open?chain (acyclic) and ring (cyclic) saturated hydrocarbons, emphasizing their structural features, nomenclature, conformational behavior (including ring strain and conformation), and the processes used in their interconversion and synthesis.

Example Problems

Example 1

What are the relative energies of transitions observed in vibrational, rotational, electronic and nuclear magnetic resonance spectroscopies?

Example 2

Convert the wavelengths (a) $500 \mathrm{nm}$ and (b) $225 \mathrm{nm}$ to $\mathrm{cm}^{-1}$ (wavenumbers). (c) Do these wavelengths fall in the visible region?

Example 3

(a) A solution of a compound X gives an absorbance reading of 0.446. What is the percentage transmittance (\% $T$ )? (b) The transmittance for another sample of $\mathbf{X}$ is $70.9 \% .$ To what absorbance reading does this correspond?

Example 4

Aqueous solutions of $\mathrm{Ni}^{2+}$ ions appear green. What is the approximate wavelength of light absorbed by aqueous $\mathrm{Ni}^{2+}$ ions?

Example 5

The absorption spectrum of benzene dissolved in cyclohexane contains bands at 183,204 and $256 \mathrm{nm} .$ (a) Which band corresponds to the lowest energy transition? (b) Which band corresponds to the lowest wavenumber? (c) For $\lambda=256 \mathrm{nm}$ $\log \varepsilon=2.30 .$ Determine the concentration of a solution (path length $=1.00 \mathrm{cm}$ ) which gives an absorbance of 0.25.