Emission Analysis of Aqueous Solutions of Groups IA and IIA Metal Salts
A student records two potassium emission spectra: 1) one using 0.10 M KNO3 solution; 2) one using 0.10 M K2SO4 solution. Will significant differences be observed in the two emission spectra? Why or why not?
I don't think so. The emission line(s) for K^+ are the same regardless of the salt. Generally, the nitrates are easier to volatilize in a flame and the intensity of the spectra may be a little stronger in nitrate salts than in sulfate salts for that reason but I wouldn't expect any other differences.
1. A student uses 6M HCl solution contaminated with Al(NO3)3 to wash the nichrome wire in between recordings of emission spectra for the different known and unknown metal ion solutions. The emission energies for the aluminum are 3.90x10^-19 J/atom, 3.58x10^-19 J/atom, and 2.97x10^-19 J/atom. How might this experimenntal error affect the identification of the metal ions present in the unknown sample? Why or why not
I am guessing yes, but I am not so sure why it would.
2. A student records two potassium emission spectra: 1) one using 0.10 M KNO3 solution; 2) one using a 0.10 M K2SO4. Will significant differences be observed in the two emission spectra? Why or Why Not? Not quite sure how to answer this...
To determine if significant differences will be observed in the two emission spectra, we need to consider the nature of the metal salts and their associated ions in the solutions.
In this case, we have two different potassium salts: KNO3 (potassium nitrate) and K2SO4 (potassium sulfate). When these salts dissolve in water, they dissociate into their respective ions, in this case, potassium (K+) and the anions nitrate (NO3-) and sulfate (SO42-).
The emission spectrum of an element is unique and corresponds to the wavelengths of light emitted by excited atoms. In the case of potassium, the emission spectrum consists of a series of lines characteristic of the transitions between energy levels of its electrons.
Now, let's consider the ions present in the solutions. Both KNO3 and K2SO4 yield potassium ions, which are responsible for the emission spectrum we are interested in. The anions (NO3- and SO42-) do not contribute to the emission spectrum since they do not have any valence electrons involved in electronic transitions.
As a result, the presence of different anions (nitrate or sulfate) does not affect the emission spectrum of potassium ions. The spectra obtained using 0.10 M KNO3 and 0.10 M K2SO4 solutions will be similar because they both contain potassium ions in the same concentration, which is the key factor determining the emission spectrum.
Therefore, the two emission spectra recorded by the student using the KNO3 and K2SO4 solutions will not have significant differences. The observed lines in the spectra will correspond to the characteristic emissions of potassium ions, regardless of the specific anion present in the salt.