Chemistry · Unit 1 · Properties and structure of atoms · Atomic structure
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In atomic absorption spectroscopy (AAS), a sample containing copper ions is aspirated into a flame where the copper atoms absorb light at a characteristic wavelength. Which statement best describes the basis of the AAS measurement method?
A 25.00 mL sample of an aqueous solution containing copper ions was analysed using atomic absorption spectroscopy (AAS). The absorbance of the sample was measured as 0.420. A calibration curve was prepared using standard copper solutions, giving the equation Absorbance = 0.00350 × [Cu²⁺] + 0.005, where [Cu²⁺] is in mg/L. Determine the concentration of copper ions in the sample.
In an atomic absorption spectroscopy (AAS) experiment, a student measures the absorbance of a series of copper ion ($\text{Cu}^{2+}$) standard solutions and obtains a calibration curve. When a sample of unknown concentration is analysed, it produces an absorbance value of 0.35. However, the student realises the sample was diluted by a factor of 2 before measurement. Which statement correctly describes the relationship between the measured absorbance and the true concentration of $\text{Cu}^{2+}$ in the undiluted sample?