Circle the questions that have been assigned. Explain why a positive flame test

Question

Circle the questions that have been assigned. Explain why a positive flame test for sodium is not an absolute confirmation f sodium ion in a test sample. The (NH_4)_2 C_2O_4 addition is omitted in the procedure. How does this affect the appearance of the flame test in Part A.2? Explain why it is good laboratory technique to conduct a comparative flame test for potassium using the 0.5 M KCl solution. Only 6 M KOH was present on the reagent shelf-there was no 6 M NaOH. Explain what effect this substitution has on the test for the presence of the ammonium ion. Instead of 6 M NaOH being added to the solution, 6 M HCl is added. How will this affect the test for the presence of ammonium ion in the solution? Explain. What is the fate of Zn^2+ in the experiment? Explain. Instead of 6 M HNO_3 being added to the solution, 6 M HCl is added (both are strong acids). How will this affect the test for the presence of copper (II) ion in the solution? Explain. Instead of conc NH_3 being added to the solution, 6 M NaOH is added (both are bases). How will this affect the test for the identification of copper(II) ion in the solution? Explain. Instead of 6 M NH_3 being added to the solution, 6 M NaOH is added (both are bases) before the addition of the k_2 C_2 O_4, What would be the appearance of the solution? Explain

Explanation / Answer

Ans 1. The sodium ions are the most common contaminants in the laboratory. A clean wire may also give yellow flame test, and if that is touched by bare hands, the sweat from the palm transferred to the wire gives it essential sodium ions to give a yellow flame.

So almost all of the sample tested for flame test may yield a positive test because of contamination of sodium and hence flame test for sodium is not an absolute test for the confirmation.of sodium ions as almost all samples may give a positive flame test

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