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1 markUltra Violet-Visible (UV/VIS) Spectroscopy

CAPE Chemistry Unit 2 · 2011 · Paper 2 · Question 5(b)(ii)

Naphthalene, P, is a constituent of coal tar.

Suggest the chromophore in naphthalene (P) that is responsible for the absorption of UV radiation.

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Other parts of this question

  1. 5(a)(i)State the source of absorption in UV/VIS spectroscopy.[1 mark]
  2. 5(a)(ii)Use an energy level diagram to show the electronic transitions that can occur in UV/VIS spectroscopy.[3 marks]
  3. 5(b)(i)Define the term 'chromophore'.[1 mark]
  4. 5(b)(iii)A sample of the solution in a cell of path length 1 cm gave an absorbance of 1.2 at a wavelength of 312 nm and an extinction coefficient of 288 dm³ mol⁻¹ cm⁻¹.…[3 marks]
  5. 5(c)Explain the use of calibration curves and standard solutions in UV/VIS analysis.[4 marks]
  6. 5(d)List TWO uses of UV/VIS spectroscopy in chemical analysis.[2 marks]

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