What is the purpose of the light source and the flame in the figure? The light source in the atomic absorption spectrophotometer serves to emit light at specific wavelengths - HSC - SSCE Chemistry - Question 20 - 2004 - Paper 1

The validity of the concentration of mercury determined in the soil sample using atomic absorption spectroscopy (AAS) is largely dependent on the calibration curve used for the analysis. Given that the average absorbance was calculated to be 0.85, it is essential to ensure that this value correlates accurately to the mercury concentration through previously established standards. Thus, the calibration should be performed with high-purity mercury standards to validate the results.

Reliability can be assessed by looking at the consistency of the absorbance measurements across the five trials, which were 0.90, 0.89, 0.89, 0.64, and 0.91. The reproducibility of these readings suggests some level of reliability; however, the measurement 0.64 is an outlier and may indicate an issue with either the sample preparation or instrument calibration. To improve reliability further, it would be beneficial to conduct additional replicate measurements and average the results, as well as ensure proper technique is maintained throughout the process.