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A section of the emission spectrum of a mercury lamp is shown - HSC - SSCE Chemistry - Question 20 - 2016 - Paper 1
Question 20
A section of the emission spectrum of a mercury lamp is shown. Light at 623.4 nm and 615.2 nm from the mercury lamp was passed through a sample of water containing ... show full transcript
Worked Solution & Example Answer:A section of the emission spectrum of a mercury lamp is shown - HSC - SSCE Chemistry - Question 20 - 2016 - Paper 1
Step 1
Which of the following pairs of intensities can be used in the determination of the amount of mercury in the water sample using atomic absorption spectroscopy (AAS)?
Answer
In atomic absorption spectroscopy (AAS), the intensity of light absorbed by a sample is directly related to the concentration of the analyte, in this case, mercury. To accurately determine the concentration of mercury, we need to compare the intensity of the light emitted from the mercury lamp (I) at a specific wavelength with the intensity detected (I_d) after passing through the sample.
The method typically requires measuring the light specifically absorbed by the analyte at its characteristic wavelengths. For this problem, the two relevant wavelengths are 623.4 nm and 615.2 nm. Therefore, we must designate the intensity of the lamp light and the detector light accordingly to utilize the data effectively for AAS.
- The most suitable option is (A) I(615.2 nm) and I_d(615.2 nm), as both intensities come from the same wavelength that relates directly to mercury's absorption characteristics.