Student A ran all her standards through the AAS at a specified C2H2/air flow rate. Just before she was to run her Cu sample, Student B turned down the flow rae of C2H2, thus lowering the flame temperature. Would students' A results of Cu in their sample be high, low or unaffected? Explain your answer.
I presume AAS stands for atomic absorption spectrophotometry.
If the T of the burner goes down (enough), there will be fewer atoms vaporized and fewer atoms available to absorb the energy being transmitted by the light source. Less energy will be absorbed, absorbance will be less and %Cu will be less.
Yes the AAS is atomic absorption spectrophotometry. Also thank you for your explanation.
In order to answer this question, we need to understand the relationship between the flame temperature and the results obtained for the Cu sample.
In flame atomic absorption spectroscopy (AAS), a sample's concentration is determined by measuring the absorption of light from a specific wavelength by the atoms in the sample. The absorption depends on the number of atoms present and their ability to absorb the light.
The flame temperature plays a crucial role in the AAS technique because it affects the atomization and excitation of the sample atoms. When a sample is introduced into the flame, it first undergoes atomization, where the chemical bonds are broken, and the atoms are dispersed in the gas phase. Then, the atoms are excited by the heat of the flame, reaching higher energy levels.
Now, coming back to the question, if Student B turned down the flow rate of C2H2, which is the fuel gas in this case, it would result in a lower flame temperature. When the flame temperature decreases, it means that the atoms in the flame will have less energy, impacting the atomization and excitation process.
In the specific case of the Cu sample, a lower flame temperature would mean that the Cu atoms would have less energy available to be excited. As a result, fewer Cu atoms would be excited to higher energy levels, leading to a decrease in the absorption of light at the specific wavelength used to measure Cu concentration.
Therefore, the result obtained for the Cu sample would be low when the flow rate of C2H2 is turned down, reducing the flame temperature. Student A's results of Cu in their sample would be affected by Student B's action of lowering the flame temperature.