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An analyst determines the concentration of calcium ions in a city’s water supply using Atomic Absorption Spectroscopy (AAS) as the analytical tool - VCE - SSCE Chemistry - Question 1 - 2005 - Paper 1
Question 1
An analyst determines the concentration of calcium ions in a city’s water supply using Atomic Absorption Spectroscopy (AAS) as the analytical tool. A simplified diag... show full transcript
Worked Solution & Example Answer:An analyst determines the concentration of calcium ions in a city’s water supply using Atomic Absorption Spectroscopy (AAS) as the analytical tool - VCE - SSCE Chemistry - Question 1 - 2005 - Paper 1
Step 1
What particular characteristic is needed by the lamp providing the light source S?
Answer
The lamp providing the light source S must emit light at a specific wavelength that corresponds to the absorption spectrum of calcium ions. This characteristic is crucial because the atomic absorption spectroscopy technique relies on the fact that the calcium ions will absorb light at this particular wavelength, allowing for accurate determination of their concentration.
Step 2
What happens to the Ca$^{2+}$ ions introduced into X? Explain your answer.
Answer
When the sample containing Ca ions is introduced into section X of the spectrophotometer, the ions enter the flame or hollow cathode lamp, depending on the system design. In this environment, the Ca ions undergo atomization, meaning they are converted into free neutral calcium atoms. These atoms then absorb light from the lamp as it passes through them, leading to a decrease in the intensity of the transmitted light. This reduction in light intensity is measured by the detector and is directly correlated with the concentration of calcium ions in the original water sample.