Spectroscopy (College Board AP® Chemistry)

Exam Questions

20 mins8 questions
11 mark

The wavelength range for ultraviolet radiation is 10-8 m, while that of infrared radiation is 10-5 m. Which type of radiation has more energy, and why?

  • Infrared has more energy because it has a lower frequency.

  • Infrared has more energy because it has a shorter wavelength.

  • Ultraviolet has more energy because it has a higher frequency.

  •  Ultraviolet has more energy because it has a longer wavelength.

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21 mark

If the frequency of a photon of electromagnetic radiation is 5.0 x 1014 Hz, determine the energy of the photon.

  • 1.33 x 10-19 J

  • 2.66 x 10-19 J

  • 3.31 x 10-19 J

  • 6.63 x 10-19 J

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31 mark

Identify the type of energy transition shown in the diagram

Diagram of a water molecule with one hydrogen (H) atom connected to two oxygen (O) atoms, each indicated by arrows pointing to the hydrogen atom.
  • microwave radiation

  • ultraviolet radiation

  • infrared radiation

  • visible light radiation

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4
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1 mark

Determine the amount of energy in joules that a carbon dioxide molecule gains when it absorbs a photon of infrared radiation of wavelength 7 x 10-7 m.

  • 2.26 x 10-19 J

  • 2.47 x 10-19 J

  • 2.62 x 10-19 J

  • 2.84 x 10-19 J

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5
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1 mark

A colored solution is analyzed by spectrophotometer. The solution has concentration 0.2 M and path length 1.00 cm. When the filter of the spectrophotometer is set to 430 nm, the absorbance is x.

If the experiment is repeated using a cuvette with 0.5 cm path length deduce the new absorbance.

  • x over 4

  • x over 2

  • x

  • 2 x

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61 mark
Graph showing a linear relationship between Ni(II) concentration (mol/L) and relative absorbance. Line of best fit is dashed, with data points as black dots.

A student creates a calibration curve of relative absorbance of a fixed wavelength of light for different concentrations of nickel(II) ions.

In a further experiment, they want to use the calibration curve to determine the number of moles of nickel(II) sulfate in a 150 mL sample of a solution of nickel(II) sulfate of unknown concentration. The unknown solution is measured and found to have a relative absorbance of 0.6. Determine the number of moles present in the sample.

  • 0.099 mol

  • 0.110 mol

  • 0.135 mol

  • 0.66 mol

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