Question

What is the effect of substituting soluble metal salts such as NaCl and K2CO3 for HCl or (NH4)2CO3 in the qualitative analysis scheme for separating the five Analytical Groups?

A. Na+ and K+ react violently with acids such as H2S, producing highly flammable and potentially explosive hydrogen gas.
B. There is no effect on the analysis since Na+ and K+ do not form a precipitate.
C. Potassium ion forms a precipitate with sulfide ion.
D. You can no longer tell if your original sample contained Na+ or K+.
E. The NaCl and K2CO3 are not pure, analytical grade materials.

Answer 1

D. You can no longer tell if your original sample contained Na+ or K+.

Step-by-step explanation:

Group reagents are the reagents which are used to separate a whole group of cations from the other groups of cations.

For example, for group 1 , the group reagent is HCl and for group 5, the group reagent is ammonium carbonate.

When sodium chloride and potassium carbonate is used, it means we are contaminating our sample with foreign cations which may interfere in the process of detection. Also, we will not be able to decipher whether the sample has these ions in the initial or not as we have added them.