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...
1. If all you are doing is identifying meal ions, the contamination of the HCl with Al will not affect the results at all UNLESS the Al energy overlaps one of those from the unknown. Why? Because it takes a certain amount of energy for the Al lines to appear and it takes A DIFFERENT energy for almost any other ion so there is no problem. You might get an emission spectrum that has Al lines as well as those of the unknown material but that won't make any difference as long as an unknown line doesn't appear EXACTLY over an Al line.
2. It takes x joules to excite a K atom whether it is in KNO3, K2SO$, K3PO4, or whatever. That is, a K line is a K line is K line. Period. So it won't make a significant difference whether one sees a K line or not; however, it often makes a difference in the INTENSITY of a K line from different compounds but not for the wavelength one sees from the K line emission spectrum.
1. In this experiment, the contaminated HCl solution could introduce aluminum ions (Al3+) into the experimental setup. This means that when the student is recording emission spectra for the different metal ion solutions, there might be interference from the aluminum ions present in the HCl solution. This can lead to erroneous results in the identification of the metal ions present in the unknown sample.
To understand why this might happen, it is important to consider that emission spectra are unique for each element. The emission energies mentioned in the question (3.90x10^-19 J/atom, 3.58x10^-19 J/atom, and 2.97x10^-19 J/atom) are characteristic energy values for aluminum. However, contamination from Al(NO3)3 in the HCl solution can result in the emission of light specifically associated with aluminum. This would make it challenging to differentiate between the emission from aluminum in the contaminated HCl solution and the actual metal ions present in the unknown sample.
To avoid such experimental errors, it is crucial to ensure proper cleaning and handling of equipment and solutions between recordings. This will help prevent contamination and ensure accurate identification of the metal ions in the unknown sample.
2. The two emission spectra recorded using a 0.10 M KNO3 solution and a 0.10 M K2SO4 solution should show significant differences.
Potassium (K) is the common element in both solutions, but the anions (NO3- and SO42-) from the respective salts will affect the emission spectra. The different anions can lead to variations in the energy levels and transitions of the potassium atoms, resulting in distinct spectral lines.
Moreover, the presence of different anions might affect the solubility and availability of potassium ions, potentially altering the concentration of K+ ions in the solution. This change in concentration can also influence the emission spectra observed.
Therefore, it is expected that significant differences would be observed between the two emission spectra recorded using the different potassium salts, due to the influence of the different anions and changes in potassium ion concentration.