Question

1. which of the following best explains what happens as photons of visible light are absorbed by dye molecules? a. certain electrons in the dye molecule move to a higher energy level, with the difference in energy between the lower and higher energy levels being the same as the energy of the absorbed photons. b. certain chemical bonds in the dye molecules begin to bend and stretch, with the difference in energy between the lower and higher vibrational states being the same as the energy of the absorbed photons. c. the dye molecules begin to rotate faster in certain modes, with the difference in energy between the lower and higher rotational states being the same as the energy of the absorbed photons. d. certain covalent bonds in the dye molecules begin to break and re - form, with the bond energies of the bonds being the same as the energy of the absorbed photons. 26. the infrared spectrum above represents the absorption of certain wavelengths of radiation by molecules of co2. which of the following best explains what occurs at the molecular level as the co2 molecules absorb photons of the infrared radiation? a. the atoms in the co2 molecules increase their vibration as the bonds between the atoms bend and stretch. b. the molecules of co2 increase the energy of their rotational motions. c. the electrons in the valence shells of the atoms in the co2 molecules are promoted to higher electronic energy levels. d. the bonds between the atoms in the co2 molecules are continuously broken and then re - form.

Explanation:

In infrared spectroscopy, molecules absorb infrared radiation which causes the atoms in the molecules to vibrate (bend and stretch). When molecules absorb photons of visible light, electrons in the molecule are promoted to higher energy levels. For CO₂ in infrared spectroscopy, the atoms in the CO₂ molecules bend and stretch upon absorption of infrared radiation. For dye - molecules absorbing visible light, electrons move to higher energy levels.

Answer:

1. D. Certain electrons in the dye molecule move to a higher energy level, with the difference in energy between the lower and higher energy levels being the same as the energy of the absorbed photons.
2. B. The atoms in the CO₂ molecules bend and stretch.